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CXC Study Guide - Chemistry Unit 2 for CAPE

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Chemistry
for
CAPE®
Unit
2
Chemistry
for
Roger
Leroy
CAPE®
Norris
Barrett
Annette
Maynard-Alleyne
Jennifer
Murray
Unit
2
3
Great
Clarendon
Oxford
It
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furthers
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Acknowledgements
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all
at
Contents
Introduction
Module
Chapter
an
1
1
1
Carbon
compounds:
introduction
in
2
1.
1
Bonding
carbon
compounds
1.2
Homologous
1.3
Determining formulae
6
1.4
Naming organic
8
1.5
Isomerism
10
1.6
Stereoisomerism
12
1.7
More
about
isomers
14
1.8
More
about
homologous
series
2
Chapter 5
Organic acids and bases
5.
1
Carboxylic
5.2
Comparing
5.3
Amines,
5.4
Amino
Chapter
acids
and
acidity
2
50
acidities
amides
52
and
acyl
halides
6
56
Polymers
58
4
compounds
series
6.
1
Addition
polymerisation
Hydrocarbons
58
6.2
Condensation
6.3
Monomers
6.4
Proteins
64
6.5
Carbohydrates
66
polymerisation
and
60
polymers
–
Module
62
1
18
Module
Chapter
The
alkanes
18
2.2
The
alkenes
20
2.3
More
2
7
Data
analysis
and
measurement
reactions of the
alkenes
Revision questions
3
68
16
2.
1
Chapter
54
acids
Exam-style questions
Chapter
50
22
7
.
1
Analysis of
24
7
.2
Accuracy
7
.3
Standards
70
scientic data
in
70
measurements
72
74
A variety of functional
Chapter
groups
8
Titrations
and
26
gravimetric
3.
1
Alcohols
26
3.2
Halogenoalkanes
28
3.3
Carbonyl
30
3.4
More
3.5
Carboxylic
3.6
Esters
3.7
Saponication
3.8
Testing for functional
compounds
analysis
76
8.
1
Principles of titrations
8.2
Titrimetric
76
analysis:
back titrations
Chapter
about
carbonyl
compounds
acids
78
32
8.3
Redox titrations
80
8.4
Some
82
8.5
Titrations
8.6
Gravimetric
analysis
(1)
86
8.7
Gravimetric
analysis
(2)
88
34
uses of titrations
36
4
and
Aromatic
4.
1
Some
reactions of
4.2
Methylbenzene
4.3
Phenols
biodiesel
compounds
benzene
and
and dyes
Revision questions
groups
nitrobenzene
without
indicators
84
38
40
42
42
44
46
48
Chapter 9
Spectroscopic methods
9.
1
Electromagnetic
9.2
Beer–Lambert’s
9.3
Ultraviolet
radiation
90
90
law
92
and visible
spectroscopy
94
iii
Contents
9.4
More
about
ultraviolet
Chapter 13
spectroscopy
96
9.5
Infrared
98
9.6
Analysing
9.7
Mass
spectrometry
9.8
Mass
spectrometry
spectroscopy
infrared
spectra
The chemical industry
13.
1
Ammonia
synthesis
13.2
The
13.3
Ethanol
13.4
The
impact of
13.5
The
electrolysis of
13.6
The
halogen
impact of
138
ammonia
140
100
142
102
ethanol
144
and organic
molecules
104
Revision questions
106
and
brine
146
chlor-alkali
industry
Chapter
10
Separation
techniques
108
148
13.7
The
production of
13.8
The
importance of
sulphuric
sulphuric
acid
150
acid
152
Revision questions
10.
1
Introduction to
10.2
More
10.3
Applications of
about
chromatography
chromatography
154
108
110
Chapter
chromatography
14 Chemistry
and the
112
environment
law
10.4
Raoult’s
10.5
Principles of distillation
and vapour
10.6
Azeotropic
pressure
mixtures
120
10.8
Solvent
122
10.9
Distillation
extraction
and
11
applications
11.2
Aluminium
11.3
More
iv
chemical
Module
2
industry
production
about
12
aluminium
Petroleum
petroleum
More
–
124
Aluminium
Locating
12.2
water
purication
156
14.2
Water
158
14.3
Ozone
14.4
The
14.5
Global
14.6
The
14.7
Acid
14.8
Pollution from fuels
170
14.9
Controlling
172
14.
10
Saving
14.
11
Solid
pollution
in the
carbon
atmosphere
160
cycle
162
warming
164
126
nitrogen
cycle
166
rain
168
pollution
3
11.
1
The
and
solvent
Exam-style questions
12.
1
cycle
118
Steam distillation
Chapter
water
and other
10.7
Chapter
The
116
distillations
Module
156
114
14.
1
extraction:
138
about
industry
petroleum fractions
resources
174
128
waste
and the
environment
Exam-style questions
128
–
Module
3
176
178
130
132
Data
sheets
180
Glossary
182
Index
186
134
134
136
Introduction
This
Study
Guide
has
been
developed
exclusively
with
the
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The
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
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On
Y
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T
est
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ourself
you
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CAPE
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in
remember
and
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are
best
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examination
sections
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Chemistry.
1
1
Carbon
1.
1
Bonding
compounds:
Learning outcomes
in
carbon
completion
of
this
section,
be
able
explain
many
because,
more
compounds
once
compounds
formed,
the
than
carbon
to
any
other
carbon
element.
(C—C)
This
single
is
covalent
to:
bonds

carbon
you
partly
should
forms
introduction
compounds
The variety of
Carbon
On
an
the
occurrence
of
are
very
strong
in
comparison
to
other
single
covalent
–1
Bond
compounds
in
terms
of
bonds.
carbon
energies:
C—C
=
–1
; N—N
350 kJ mol
=
160 kJ mol
;
bonding
–1
O—O

understand
the
‘tetravalency’
understand
‘catenation’
bonding
It
takes
a
in
lot
are
in
terms
and
are
to
hydrogen
is
and
elements
organic
years
ago
are
Berzelius
Most
the
char
(go
so
the
form
compounds
chains
or
ring
together
(see
is
called
Unit
1
catenation.
Study
Guide ,
Carbon–carbon
Section
vulnerability
in
Group
carbon
IV
of
the
to
attacks
by
other
2.5)
and
this
chemicals.
compounds
it
has
four
Periodic
valence
T
able.
It
electrons
exhibits
in
its
tetravalency .
outer
shell,
which
are
able
to
form
bonds
with
other
principle
atoms.
is
formed
by
the
sharing
of
two
electrons,
one
A
from
Carbon
chemicals
and
form
four
bonds
because
one
of
the
each
2s
electrons
atom
when
is
transferred
to
a
2p
orbital
to
give
the
four
unpaired
in
the
into
necessary
for
forming
four
bonds
(Figure
1.1.1).
inorganic.
compounds
black)
can
Swedish Chemist
organic
organic
to
compounds. About
divided
groups:
their
that
bond
electrons
two
bonds,
atoms
often
carbon
J.
strong
carbon
perhaps
atom.
200
in
means
covalent
called
joining
non-polar
reduce
quantum
other
these
of
usually
This
some
by
also
Hybridisation
Carbon
containing
break
ability
resonance.
Did you know?
compounds
to
The
of
helps
Carbon
energy
carbon
bonds
hybridisation
of
stable.
compounds
compounds
150 kJ mol
terms
and
formed

=
burn
heated.
a
or
unpaired
b
electrons
Most
2p
inorganic
chemicals
just
melt.
2s
four
paired
Figure 1.1.1
unpaired
electrons
electrons
a The electron configuration of carbon in the ground state; b The electron
configuration of carbon when about to form covalent bonds. Each electron can form
3
orbitals.
equivalent sp
The
promotion
compensated
other
C
(or
thought
-bonds
This
of
H,
as
process
of
for
O
a
electron
the
or
being
of
2s
by
N)
energy
atoms.
mixed
mixing
so
requires
released
The
that
atomic
four
each
orbitals
energy.
when
unlled
has
is


But
four
s
this
C
more
are
atomic
character
called
is
bonds
than
formed
orbitals
and


p
hybridisation .
with
can
be
character
.
These
3
mixed
form
orbitals
single
between
(see
Figure 1.1.2
The structure of ethane. The
of
bonds
carbon
Unit
these
are
1
in
H,
hybrid
sp
between
and
Study
bonds
called
O
Guide ,
ethane
carbon
or
N
atoms
atoms.
Section
by
orbitals.
the
2.9).
These
and
These
Figure
combination
orbitals
other
are
σ
1.1.2
of
carbon
bonds
atoms
(sigma
shows
separate
overlap
the
to
or
bonds)
formation
atomic
orbitals.
3
molecular orbitals formed from sp
allow each bond to be a σ-bond.
hybrids
In
ethene,
one
singly
occupied
2s
orbital
and
two
of
the
three
singly
2
occupied
2p
orbitals
in
each
carbon
atom
similar
shapes
to
hybridise
to
make
three
3
orbitals.
form
σ
These
bonds
which
approximately
The
120º
remaining
form
2
have
a
π
bond
2p
are
arranged
with
each
orbitals
(Figure
a
sp
2
orbitals.
plane
These
making
a
sp
bond
orbitals
angle
of
other
.
from
1.1.3).
in
sp
each
carbon
atom
overlap
sideways
to
Chapter
-bond
1
Carbon
compounds:
an
introduction
-bonds
2
Figure 1.1.3
Ethene has sp
orbitals in one plane making σ bonds and a π bond above and
below this plane
Resonance
In
ethane
and
positions.
more
In
atoms,
These
ethene
some
allowing
electrons
Benzene,
H
C
6
shows
a
are
,
is
structures.
said
has
six
a
single
The
to
be
localised,
molecular
electrons
free
carbon
atoms
of
benzene.
between
are
several
structure
movement
arranged
in
the
somewhere
different
is
called
a
The
form
↔
they
are
extend
over
a
means
which
carbon
lies
in
particular
over
these
ring.
three
or
atoms.
Figure
in-between.
structures
is
resonance
that
the
between
atoms
are
1.1.4(a)
called
actual
these
neither
Making
up
a
two
double
nor
composite
mesomerism .
The
hybrid.
a
Figure 1.1.4
i.e.
orbitals
delocalised
(composite)
bonds
They
from
composite
are
the
6
bonds.
structure
electrons
the
representation
structure
single
the
substances,
b
a Two possible ways of representing benzene; b A modern representation of
benzene
2
In
benzene,
hybrid
the
orbitals
six
carbon
(one
to
atoms
each
form
hydrogen
a
hexagon
atom
and
with
two
to
three
localised
other
carbon
sp
2
atoms).
The
three
orbitals
sp
are
arranged
in
a
plane,
so
the
bond
angles
o
are
.
120
These
The
orbitals
six
such
as
called
This
leaves
overlap
electrons
benzene,
aryl
a
single
p
orbital
sideways
involved
which
can
have
to
form
move
this
on
each
a
of
the
six
delocalised
freely
around
delocalised
carbon
system
the
electron
ring.
ring
atoms.
of
π
bonds.
Compounds
structure
are
Exam tips
compounds
It
is
a
common
resonance
two
or
They
are
single
in
many
lines.

A
large
joining
atoms

Most
number
of
or

ring
organic
the C—C
of
carbon
carbon
atoms
are formed
to form
straight
by
catenation
or
branched
–
the
chains
bond
compounds
energy
of
s
shows
and
and
p
the
are
stable
non-polar
atomic
orbitals
because
nature
results
of
in
of
this
the
high
value
of
bond.
the formation
using
a
of
the
a
with
mixed
Resonance
is
a
use
and
of
Figure
can
structure
dashed
two
representing
between’
of
structure.
shows
a
1.
1.5(b)
structure
line.
O
b
O
RC
RC
O
O
character.
Figure 1.1.5

the
O
O
orbital
of
dashed
RC
an
by
ion
‘in
that
structures. We
1.
1.5(a)
ways
carboxylate
of
think
mixtures
‘in-between’
cases
Figure
possible
of
compounds.
carbon
Hybridisation
compounds
together
the
to
are
more forms
represent
Key points
error
hybrids
where
the
structure
of
a
compound
is
a
single form
which
a
Two possible ways of
is
representing a carboxylate ion; b The
‘in-between’
two
or
more
extreme
structures.
‘in-between’ structure using a dashed line
3
1.2
Homologous
Learning outcomes
What
A
On
completion
of
this
series
section,
is
a
homologous
be
able
series
is
a
series?
group
of
organic
compounds
with
the
same
you
functional
should
homologous
group
in
which
each
successive
member
increases
by
the
to:
unit
—CH
2

explain
the
meaning
of
A
homologous
functional
its

group
is
an
atom
or
group
of
atoms
describe
the
chemical
and
physical
characteristics
particular
present
in
chemical
methanol,
properties.
OH,
CH
For
and
example,
ethanol,
C
3
of
formula’

write
a
gives
a
compound
the
and
H
2
functional
OH,
is
group
—OH.
5
table
below
shows
the
names
of
some
homologous
series
and
series
functional
understand
the
a
The
homologous

that
series
terms
groups.
‘empirical
Homologous
‘molecular formula’
structural formula
series
Functional
a
molecular formula
other
relevant
Example
when
C= C
alkene
given
group
ethene, C
H
2
4
ethanol, C
H
and
information.
alcohol
—OH
2
halogenoalkane
—F,
—Cl,
—Br
or
—I
OH
5
chloromethane, CH
Cl
3
O
propanoic
=
carboxylic
CO
acid
H
C
H
2
Each

homologous
A
particular
particular
or
series
has
general
series,
e.g.
the

following
formula
H
C
n
C
acid,
H
2
O
which
for
CO
5
H
2
characteristics:
applies
alkanes
to
all
(where
n
members
=
in
number
a
of
2n+2
atoms).
Each
successive
member
increases
by
the
unit
.
—CH
For
example
in
2
the
alkane
homologous
series:
CH
,
C
4

The
members
they

have
The
carbon
Empirical
of
The
The
and
molecular
C
chemical
H
3
C
8,
H
4
properties.
in
a
regular
alkanes
way,
e.g.
increases,
This
is
because
as
the
the
number
boiling
present
in
a
are
shows
in
a
the
shows
is
given
simplest
whole
number
ratio
of
atoms
compound.
molecule
formula
examples
the
of
a
actual
sometimes
in
the
number
of
atoms
of
each
compound.
table
the
same
as
the
molecular
formula.
below:
Compound
Empirical formula
Molecular formula
ethane
CH
C
pentane
C
acid
C
12
CO
6
H
5
H
C
2
benzene
H
2
H
5
ethanedioic
of
point
molecular formulae
3
12
O
2
CH
C
dinitrobenzene
C
H
3
NO
2
C
2
H
4
2
H
6
4
10
group.
change
straight-chain
for mula
present
empirical
Some
functional
for mula
element
element
in
similar
,
6
regularly.
empirical
each
same
very
properties
atoms
increases
The
the
physical
have
H
2
H
6
6
N
4
O
2
4
Chapter
1
Structural formulae
The
in
a
str uctural
simplied
for mula
form.

a
displayed

a
condensed
For
A
shows
the
structural
for mula ,
showing
for mula ,
where
arrangement
formula
all
can
atoms
bonds
are
of
be
and
not
atoms
in
a
molecule
either:
bonds
shown.
example:
H
H
C
C
H
H
H
H
CH
CH
3
ethane
H
(displayed)
H
H
C
C
ethane
3
(condensed)
H
H
C
N
H
H
H
H
CH
CH
3
propylamine
With
still
chain
show
Hexane,
(displayed)
hydrocarbons ,
the
actual
CH
CH
3
we
can
CH
CH
2
CH
2
condense
For
2
(condensed)
formula
even
more
and
example:
CH
2
the
NH
2
propylamine
structure.
2
CH
2
,
can
be
written
CH
3
(CH
3
)
2
CH
4
3
Did you know?
In
condensed
shown
in
formulae,
side
branches
coming
off
the
main
chain
are
brackets.
More
are
than
made
100 000
each
new
year
by
compounds
research
H
chemists.
H
compounds
H
C
branches
H
H
C
C
C
H
H
H
The
structure of
H
CH
(displayed)
ring
H
these
containing
(side
chains).
are
organic
rings
and
Some
also
be
incorporated
into
metals
organic
compounds.
CH(CH
3
methylbutane
of
H
can
H
Most
)CH
3
methylbutane
CH
2
3
(condensed)
compounds
Key points
H
C
H
H
C

A
homologous
series
is
a
group
C
H
H
H
H
C
of
organic
the
compounds
same functional
with
group
in
C
H
which
H
C
H
H
each
increases
successive
by
the
unit
member
—CH
2
cyclohexane
(displayed)
cyclohexane
(condensed)

The
empirical formula
simplest
whole
shows
number
ratio
the
of
H
atoms
C
H
H
C
C
C
C
a

H
C
The
each
element
molecular formula
actual
H
of
present
in
compound.
number
element
of
present
shows
atoms
in
a
of
the
each
molecule
of
H
a
benzene
(displayed)
benzene
compound.
(condensed)

The
structure
compounds
The
ring
inside
the
hexagon
in
benzene
represents
the
delocalised
ring
(see
Unit
1
Study
Guide ,
Section
organic
be
written
as
of
displayed
electrons
of
can
or
condensed formulae.
2.9).
5
1.3
Determining formulae
Learning outcomes
Deducing the
Worked
On
completion
should

be
able
deduce
of
this
section,
masses
masses
In
of
or
relative
elements
in
1
this
example,
we
are
given
information
about
percentage
(%)
by
mass.
using
Calculate
absolute
example
you
to:
empirical formulae
empirical formula
a
iodine
by
the
that
mass.
empirical
contains
values:
(A
formula
8.45%
C
=
of
a
carbon,
12.0,
H
compound
2.11%
=
1.0,
I
of
carbon,
hydrogen
=
and
hydrogen
89.44%
and
iodine
127.0).
r
compound
Step

deduce
1:
Assume
that
we
have
100 g
of
the
compound,
then
each
of
the
molecular formulae from
percentages
can
be
converted
to
mass,
that
is
8.45 g
carbon,
empirical formulae
2.11 g

deduce
hydrogen
and
89.44 g
of
iodine.
molecular formulae from
Divide
mass
by
to
A
determine
number
of
moles
of
each
atom
in
r
combustion
data.
the
compound:
C
H
8.45
=
2:
=
2.11 mol
=
1.0
Divide
by
lowest
0.704
number
to
get
2.11
the
formula
ratio:
0.704
=
3
=
0.704
W
rite
mole
______
1
0.704
0.704 mol
127.0
______
=
3:
______
0.704 mol
______
Step
89.4
_____
12.0
Step
I
2.11
_____
1
0.704
showing
the
simplest
ratio:
CH
I
3
Deducing the
We
can
determine

the
empirical

the
molar
The

molar
Section

using
a
Worked
6.00 g
The
First
Step
of
a
work
formula
if
we
know:
formula
of
of
a
the
compound.
compound
known
mass
volume
of
spectrometer
example
a
molecular
can
be
gas
or
found
by:
vapour
(see
Unit
1
Study
Guide ,
5.3)
molecular
out
Divide
the
contains
mass
of
empirical
mass
(see
Section
9.7).
2
hydrocarbon
relative
1:
the
mass
mass
weighing
molecular formula
by
A
4.80 g
the
of
carbon
hydrocarbon
and
is
1.20 g
of
hydrogen.
30.
for mula:
:
r
C
H
4.80
1.2
_____
____
=
0.400 mol
=
12.0
Step
2:
Divide
by
lowest
number
to
get
0.400
1
=
0.400
W
rite
the
formula
ratio:
______
=
3:
mole
1.20
______
Step
1.2 mol
1.0
showing
3
0.400
the
simplest
ratio
of
atoms:
CH
3
Then
Step
6
deduce
4:
Find
the
the
molecular
empirical
for mula:
formula
mass:
12.0
+
(3
×
1.0)
=
15.0
Chapter
Step
5:
Divide
the
formula
molar
mass
of
the
compound
by
the
1
Carbon
compounds:
an
introduction
empirical
mass:
30
___
=
2
15
Step
6:
Multiply
deduced
each
in
atom
Step
5:
in
the
empirical
×
CH
2
=
C
3
Molecular formula
The
worked
deduce
the
example
Worked
below
shows
formula
law
that
temperature
states
and
pressure
example
2
of
equal
have
how
a
we
can
compound
volumes
equal
by
the
number
6
using Avogadro’s
molecular
Avogadro’s
formula
H
of
law
use
Avogadro’s
using
all
gases
numbers
of
law
combustion
at
the
to
data.
same
molecules.
3
3
Propane
contains
carbon
and
hydrogen
only.
3
reacts
with
Deduce
for
the
Step
1:
exactly
the
oxygen,
125 cm
molecular
formula
W
rite
the
information
H
x
of
75 cm
(g)
+
O
Find
the
H
x
Deduce
the
(g)
write
→ CO
(so
(g)
ratio
+
of
5O
y
(g)
5
number
of
x
must
be
equation
Deduce
gases
(g)
and
→
C

6
of

So

4
4
(g)
the
use
3CO
3
(g)
1 mol
10
of
the
+
of
(g)
+
H
law:
O(l)
2
C
H
→
3 mol
CO
y
2
→
3CO
water
come
→
H
(g)
3CO
(g)+
react
react
formed
the
+
H
O(l)
2
with
with
carbon.
hydrogen
containing
8
to
form
hydrogen
water
.
atoms
propane.
5O
8
(g)
→
3CO
2
molecular
O(l)
2
2
must
are
from
H
atoms:
(g)
atoms
atoms
(g)+
2
H
5O
oxygen
3
W
rite
(g)
2
C
5:
5O
y
moles
Avogadro’s
volumes
2
oxygen
which
+
number
H
3
O(l)
2
2
atoms:
y
the
H
equation:
3)
H
3
Step
formed.
balanced
3
volumes
C
+
2
2
volume
C
4:
propane
is
75 cm
x
Step
of
dioxide
a
unbalanced
3
125 cm
simplest
C
1
3:
carbon
and
2
3
Step
of
propane
below
y
25 cm
2:
25 cm
reaction.
C
Step
When
3
formula:
(g)+
4H
2
x
=
3,
y
O(l)
2
=
8.
So
formula
is
C
H
3
8
Key points

Empirical formulae
elements

Molecular
using

A
a
masses
mass
are
in
a
molecular
are found
can
mass
Molecular formulae
Avogadro’s
deduced
using
masses
or
relative
masses
of
the
compound.
by
weighing
known
volumes
of
gases
or
by
spectrometer.
molecular formula
relative

present
can
be
of
be
deduced from
the
compound
deduced from
the
is
empirical formula
if
the
known.
combustion
data
by
applying
law.
7
1.4
Naming
Learning outcomes
organic
The
We
On
completion
of
this
section,
IUPAC
use
a
set
be
able
understand
organic
name
the
carbon
alkanes
rules for
used
of
tell
us
to
with
carbon
atoms
Stem
about
simple
carbon
The
stem:
in
of
the
IUPAC
by
a
carbon
compounds
may
have
several
parts
to
their
name:
tells
a
us
how
many
compound.
table
The
carbon
names
atoms
of
the
there
rst
are
10
along
stems
below.
meth-
eth-
prop-
but-
pent-
hex-
hept-
oct-
non-
dec-
A
suffix:
this
A
is
functional
tells
and
prefix:
us
the
for
often
added
groups
that
stem,
some
to
the
end
present.
For
example,
the
compound
prop-
tells
homologous
us
it
of
is
the
in
has
stem.
the
the
This
sufx
alcohol
three
series,
the
functional
the
bromo -
in
was
drawn
of
atoms.
prex
before
the
stem.
For
group
in
the
appears
up
tells
series
us
that
and
the
the
compound
but-
tells
us
it
is
in
has
the
four
halogenoalkane
carbon
atoms.
committee
Some
task
examples
are
shown
in
the
table
below.
of
in
1892. The
was founded
in
1919
by
Homologous
series
Sufx
No. of C
-ane
5
atoms
Name
and formula
a
pentane, C
H
5
from
universities
in
industry
order
to
12
and
define
alkene
-ene
3
propene, C
H
3
standards
of
naming
measurements
can
be
applied
in
as
name
(IUPAC)
years. The
chemists from
about
name
Pure
in Geneva
of
us
the
homologous
carbon
example,
tells
–ol
naming
alkane
group
the
are
10
and Applied Chemistry
begun
can
compounds.
9
homologous
chemists
carbon
8
series,
compounds
this
bromobutanol
was
organic
7
International Union
of
of
6
rules for
number
structure
5
a
a
a
4

over
the
compounds
chain
propanol
the
in
names
3
Did you know?
by
Systematic
2
the
chemical
compounds
1

of
Naming
nomenclature.
atoms.
shown
system
compounds.
systematic
branched
main
The
name
a
compounds

No. of C
to
called
naming
Simple
chains
rules
is
Naming

of
way
to:
be

rules
you
particular
should
compounds
chemicals
chemistry
throughout
alcohol
which
the
6
and
-ol
7
heptanol, C
H
7
OH
15
world.
carboxylic
acid
-oic
acid
1
methanoic
HCO
acid,
H
2
ketone
-one
4
butanone,
CH
CH
3
Naming

The
branched-chain
position
numbering

The

Numbering
for
longest
the
side
of
the
side
chains
carbon
possible
starts
at
chain
alkanes
or
functional
the
side
chain
prexes

The
side
chain
is
of
end
carbon
that
atoms
gives
the
For
(comes
named
example
before)
according
CH
—
is
to
the
the
methyl,
3
formed
8
These
by
groups
is
shown
by
is
chosen.
smallest
number
possible
chain.
The
propyl.
3
atoms.

contains.
COCH
2
groups
changing
are
the
of
alkyl
H
groups.
‘alkane’
name.
number
C
2
called
‘ane’
stem
to
—
is
of
carbon
ethyl,
5
The
‘yl’.
C
atoms
H
3
alkyl
group
—
it
is
7
name
is
Chapter
Example
1
1
2
CH
3
1
Carbon
compounds:
an
introduction
4
CHCH
is
CH
3
2
2–methylpentane
Exam tips
3
CH
3
prefix
position
side
Make
sure
is
longest
Example
5
4
CH
3
CH
3
2
2
the
off ’
that C—C
1
CHCH
2
is
CH
2
C
example
six
More than one
and
is
more
the
tetra-
Example
chain
carefully from
diagrams.
bonds
below
carbon
Remember
rotate freely.
than
prexes
for
side
four
one
di-
the
for
the
two
longest
In
the
chain
is
stem
chain?
of
the
atoms.
C
use
which
5
prefix
we
out
3– ethylhexane
3
H
2
there
work
2
CH
If
you
chain
‘squared
6
that
stem
of
C
C
C
C
C
same
alkyl
groups
the
side
chain
same,
tri-
or
for
functional
three
the
group
C
same
same.
3
CH
3
1
2
CH
3
4
CCH
3
CH
2
3
CH
3
2,2-dimethylbutane
Note:

numbers
are
separated
from
each

numbers
are
separated
from
words
If
there
are
Example
different
side
chains,
they
4
by
by
commas
hyphens.
are
listed
Example
C
in
alphabetical
order
.
5
H
2
CH
other
I
H
H
C
C
C
5
CHCHCH
3
CH
2
CH
2
H
H
3
CH
H
Cl
H
3
3-ethyl-2-methylhexane
Functional
The
the
group
numbering
general
alkenes
is
Example
of
rules.
between
positions
functional
But
note
the
2-chloro -1-iodopropane
groups
that
prex
the
and
the
6
CH
along
the
number
CH=CHCH
CH
2
chain
to
the
follows
C =C
many
bond
of
in
stem.
Example
3
side
given
7
HOCH
3
CH
2
pent-2-ene
CH
2
OH
2
propane-1,3-diol
Key points

The
rules for
stem,

Suffixes,
group

meth-,
e.g.
organic
eth-,
–ane,
prop-,
-ene,
-ol,
carbon
compounds
are
based
on
the
use
a
etc.
are
added
to
the
stem
to
show
the functional
present.
Prefixes,
group

e.g.
naming
e.g.
chloro-,
may
be
added
to
the
stem
to
show
the functional
present.
Numbers
are
used
to
show
the
position
of
particular
side
chains.
9
1.5
Isomerism
Isomers
Learning outcomes
atoms
On
completion
should

be
define
able
the
of
this
section,
are
are
molecules
arranged
that
have
differently.
the
The
same
two
molecular
main
types
formula
of
but
isomerism
the
are:
you

structural
isomerism

stereoisomerism
to:
term
(see
Section
1.6).
‘structural
isomer’

understand
between
the
chain
Structural
difference
and
isomerism
position
Str uctural
isomers
are
compounds
with
the
same
molecular
formula
but
isomers
different

explain
about
that
single
carbon
there
is free
bonds
in
rotation
chains
structural
formulae.
There
are
three
types
of
structural
isomerism:
of

chain
isomerism

functional

positional
atoms.
Chain
Chain
group
isomerism.
isomerism
isomerism
carbon
atoms
Example
Butane
isomerism
in
is
where
their
the
carbon
isomers
differ
in
the
arrangement
and
methylpropane
both
have
the
molecular
H
formula
H
H
H
C
C
C
H
H
H
H
H
H
C
H
C
C
C
C
H
Methylpropane
possible
Example
H
H
methylpropane
is
not
position
named
for
the
2-methylpropane
side
because
there
H
H
H
H
H
H
C
C
C
H
H
H
C
C
H
C
H
H
C
The
functional
H
H
group
H
C
H
H
butan-1- ol
2-methylpropan-1- ol
is
in
the
1-position,
so
this
is
not
positional
isomerism.
Functional
Functional
isomers
10
is
chain.
2
H
Note:
H
H
H
butane
one
10
H
H
H
only
the
1
4
Note:
of
skeleton.
is
group
group
the
isomerism
isomerism
same
but
the
is
where
functional
the
molecular
groups
are
formula
different.
of
the
Chapter
Example
3
For
C
H
2
group
(an
ether).
because
two
they
and
an
can
draw
isomer
isomers
belong
H
H
C
C
H
H
H
we
an
isomer
with
to
have
with
an
different
different
—O—
Positional
different
homologous
C
H
3
Cl
6
and
compounds:
an
introduction
functional
group
physical
(an
properties
series.
H
O
H
H
C
H
H
H
methoxymethane
isomerism
isomerism
in
— OH
functional
chemical
ethanol
Positional
an
Carbon
6
alcohol)
These
O
1
each
has
is
where
isomer
.
four
The
possible
the
position
compound
of
with
the
the
functional
molecular
group
is
formula
isomers.
2
Cl
H
Cl
H
C
C
C
H
H
H
Cl
H
H
H
H
H
C
C
C
Cl
H
H
There
is
free
and
H
H
care
when
sure
that
you
formulae
about
drawing
don’t
below
not
H
H
H
C
H
Cl
H
rotation
single
the
bonds.
H
Br
C
C
H
H
Because
formulae
same
isomers.
H
C
2,2-dichloropropane
structural
repeat
are
Cl
H
bond
rotation
take
H
Cl
1,3-dichloropropane
1,1-dichloropropane
Isomerism
C
H
1,2-dichloropropane
Cl
C
H
of
structure.
They
are
H
the
H
of
this,
different
For
example,
same
H
H
C
C
H
Br
you
need
isomers,
the
to
making
two
compound.
H
Key points

Structural
different

Chain

atoms
Functional
is
the
Positional

Know
is
compounds
but
where
their
the
carbon
with
the
same
molecular formula
but
isomerism
isomers
each
there
is
differ
in
the
arrangement
of
the
skeleton.
is
the functional
isomerism
in
that
in
group
same
different
are
structural formulae.
isomerism
carbon

isomers
where
where
groups
the
the
are
molecular formula
of
the
isomers
different.
position
of
the functional
group
is
isomer.
is free
rotation
about
single
bonds
in
chains
of
carbon
atoms.
11
1.6
Stereoisomerism
Learning outcomes
What
is
stereoisomerism?
Stereoisomerism
On
completion
of
this
section,
atoms
should
be
able
explain
of

the
stereoisomerism
structure
understand
the
double
the
of
in
know
that
to
a
where
each
two
other
(or
but
more)
the
compounds
atoms
have
a
have
the
different
same
arrangement
There
are
in

geometrical

optical
in
stereoisomerism:
isomerism
(also
called
cis
trans
isomerism)
of
type
(cis-trans)
isomerism
is
is
free
rotation
around
single
bonds.
But
there
is
no
free
rotation
of
about
asymmetry
of
geometrical
isomerism
particular
types
isomerism.
Geometrical
optical
two
molecules
importance
bond
space.
There
due
to
terms
isomerism

bonded
to:
in

is
you
a
double
C=C
bond
(or
other
double
bonds).
This
can
result
in
molecules.
geometrical
substituent
same
side
Example
The
two
isomerism .
groups
(cis)
or
Geometrical
either
on
the
side
of
a
opposite
isomerism
double
sides
bond
occurs
are
on
the
( trans).
forms
of
cis-
and
trans-dichloroethene
are
Cl
different
Cl
=
C
C
H
H
H
cis-dichloroethene
the
cis-isomer
isomers.
H
=
C
C
In
the
either
1
Cl

when
arranged
both
Cl
Cl
trans-dichloroethene
atoms
are
on
the
same
side
of
the
C =C
bond.

In
the
trans-isomer
the
Cl
atoms
are
on
opposite
sides
of
the
C =C
bond.

The
two
may
geometric
have
Example
some
isomers
chemical
have
different
properties
physical
which
are
CH
they
H
CH
CH
2
3
3
3
=
C
C
C
C
=
H
Optical
CH
H
H
CH
2
cis-pent-2-ene
Optical
and
different.
2
CH
Cl
properties
slightly
3
trans-pent-2-ene
isomerism
isomerism
happens
when
four
different
groups
are
attached
to
a
Cl
central
C
C
other
.
carbon
They
atom.
are
not
The
two
identical
isomers
because
formed
they
are
cannot
mirror
be
images
of
each
superimposed
r
H
H
(matched
they
do
up
not
exactly)
match
on
up
one
another
.
exactly.
An
However
example
is
you
try
to
rotate
them,
bromochlorofluoromethane.
mirror
This
Figure 1.6.1
The two optical isomers of
two
has
four
mirror
different
images
groups
(Figure
attached
to
the
central
carbon
and
exists
as
1.6.1).
bromochlorofluoromethane are mirror
images
These
but
by
light
optical
an
only
We
rotate
amount.
vibrates
directions.
12
isomers
equal
use
in
one
an
plane-polarised
The
light
electromagnetic
plane
unlike
instrument
ordinary
called
a
in
eld
opposite
in
light
which
polarimeter
directions
plane-polarised
to
vibrates
measure
in
the
all
Chapter
rotation
which
(+)
of
this
rotates
plane-polarised
plane-polarised
enantiomer
.
direction
optical
is
The
called
isomer
the
(–)
light
light
by
in
which
optical
a
rotated
enantiomer
.
isomers.
clockwise
it
in
The
direction
an
1
Carbon
compounds:
an
introduction
isomer
is
called
the
anticlockwise
(Enantiomer
is
another
word
for
isomer
.)
Did you know?
The
amino
optical
acids
fortunate for
are
the
T
wo
the
and
isomers. Our
more
that
the
optical
examples
central
groups
us
correct
carbohydrates
bodies
atom
attached
amino
of
optical
not
in
our
deal
acids
isomers for
does
to
cannot
and
our
to
are
their
particular forms
mirror
carbohydrates
images.
we
It
of
is
get from
our food
bodies.
isomers
have
bodies
with
be
are
shown
carbon
as
below.
long
as
Y
ou
it
can
has
4
see
that
different
it.
a
CH
CH
3
3
C
C
NH
CO
2
H
HO
2
2
2
H
H
b
CH
CH
3
3
Sn
C
Sn
H
2
C
5
A
a
carbon
chiral
C
9
H
4
C
9
H
3
Figure 1.6.2
H
4
C
H
2
C
7
5
H
3
7
Optical isomers of a alanine (an amino acid) and b tin tetraalkyl
(or
other
centre .
atom)
Some
with
four
molecules,
different
e.g.
groups
glucose,
have
attached
more
to
than
it
is
one
called
chiral
centre.
Did you know?
The
word
mirror
the
chiral
image
comes from
of
your
right
the
hand
ancient Greek for
but
you
cannot
‘hand’. Your
superimpose
left
one
hand
is
exactly
a
on
other.
Key points

Geometrical
isomerism
double
are
sides

each
Optical
to
a
other
in
A
opposite
carbon
the
either
on
substituent
the
same
groups
side
(cis)
either
or
on
side
the
of
a
opposite
two
atoms
happens
atom,
mirror
compounds
have
a
when four
resulting
have
different
in
different
a
image. Optical
the
same
atoms
arrangement
groups
molecule
isomers
that
rotate
in
are
has
bonded
space.
attached
a
non-
plane-polarised
light
directions.
centre
different
where
the
isomerism
central
chiral
is
but
superimposable

arranged
when
(trans).
Stereoisomerism
to

bond
is
(in
groups
its
most
attached
common
to
case)
is
an
atom
that
has four
it.
13
1.7
More
about
Learning outcomes
Branched-chain
As
On
completion
should
be
able
of
this
isomers
section,
the
number
of
alkanes
carbon
atoms
number
of
possible
isomers
draw
all
the
isomers
of
pentadecane,
increases
longest
rapidly.
carbon
For
chain
example
increases,
there
are
the
4347
to:
H
C
15

in
you
the
isomers for
a
given
of
a
particular
alkane.
The
.
Y
ou
may
be
asked
to
draw
all
the
isomers
32
example
below
shows
you
how
to
do
this.
molecular formula

draw
isomers for
alkenes
and
ring
Example
structures.
Draw
all
the
isomers
of
hexane,
C
H
6
1
Start
2
Draw
(ve
3
the
the
Draw
the
straight-chain
isomers
carbon
(four
4
with
atoms
isomers
carbon
with
in
one
the
with
:
14
isomer
fewer
(six
carbon
carbon
atom
carbon
atoms
atoms
in
the
in
line).
longest
chain
chain).
two
fewer
in
the
longest
chain
atoms).
For
longer-chain
the
isomer
is
alkanes
not
one
continue
that
H
you
in
have
this
way
already
H
H
H
H
C
C
C
C
H
H
H
H
H
until
you
are
sure
that
drawn.
H
H
H
H
hexane
H
H
C
H
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
2-methylpentane
H
Exam tips
When
writing
isomers,
note
C
H
H
H
H
H
C
C
C
C
H
H
H
H
H
H
H
that:
3-methylpentane
1
A
carbon
chain
like
H
this
C
H
C
C
H
C
C
H
H
H
C
C
H
H
H
H
C
C
C
C
H
H
has
five
carbon
atoms
in
C
H
H
C
H
H
H
C
H
longest
chain,
A
carbon
chain
C
C
C
C
C
C
like
2-dimethylbutane
H
C
C
C
C
H
H
H
H
this
2,
Figure 1.7.1
is
the
same
C
14
as
C
C
C
C
this
C
H
H
not four.
2,
2
H
the
The five isomers of hexane
3-dimethylbutane
H
Chapter
The
isomers of C
The
molecular
formula
compounds:
an
introduction
8
C
H
4
double
Carbon
H
4
containing
1
bonds
suggests
an
alkene.
Possible
isomers
8
are:
H
H
H
H
H
C
C
C
H
C
H
H
H
C
H
C
C
H
H
H
H
H
but-1-ene
2-methylpropene
H
H
H
H
H
C
H
H
H
C
=
C
C
C
H
H
H
=
C
C
trans-but-2-ene
cis-but-2-ene
There
The
is
also
prex
the
possibility
cyclo -
is
of
a
cyclic
H
H
H
C
C
H
H
C
C
H
H
H
used
H
H
H
H
H
C
to
alkene,
cyclobutane.
cyclobutane
indicate
a
ring
structure
which
is
not
an
aryl
compound.
Aryl
Aryl
If
a
compounds
compounds
single
alkyl
contain
group
is
at
least
attached
one
to
benzene
the
ring,
ring.
we
do
not
number
this
group.
If
there
is
positions
more
by
C
a
than
giving
H
2
one
them
b
5
alkyl
the
group
CH
i
attached
smallest
the
ring
we
show
their
possible.
CH
ii
3
to
numbers
CH
iii
3
3
CH
3
CH
3
CH
3
Figure 1.7.2
a Ethylbenzene; b The three isomers of dimethylbenzene,
i 1,2-dimethylbenzene, ii 1,3-dimethylbenzene and iii 1,4-dimethylbenzene
Key points

The
larger
number

of
the
Compounds
substituted

Alkenes
number
possible
containing
in
may
of
different
be
carbon
atoms
in
a
hydrocarbon,
the
greater
or
groups
is
the
isomers.
rings
may
positions
isomeric
with
have
in
ring
the
two
more
alkyl
ring.
compounds.
15
1.8
More
about
Learning outcomes
The
A
On
completion
should
be
able
of
this
homologous
section,
alcohol
homologous
series
homologous
series
can
be
series
identied
by:
you
to:

the
functional
group
it
contains
(and
hence
its
typical
chemical
reactions)

describe
the
the functional
homologous
alkanes,
alkenes,
series
group
in

of
a
The

write
given
aldehydes
formula.
alcohols,
halogenoalkanes,
acids,
general
alcohol
homologous
series
has:
carboxylic
and
general formulae for
homologous

an

the
—OH
functional
group
ketones
general
formula
C
H
n
a
OH.
2n+1
series.
The
table
below
members
of
the
shows
the
alcohol
Number of C
names
and
homologous
Name
atoms
1
structural
formulae
of
methanol
ethanol
Structural
formula
formula
CH
CH
O
C
H
2
3
propan-1-ol
C
butan-1-ol
O
H
C
pentan-1-ol
O
6
hexan-1-ol
7
heptan-1ol
C
octan-1-ol
9
nonan-1-ol
C
H
decan-1-ol
C
Y
ou
will
have
end
the
of
also
notice
sufx
the
be
alcohol
in
H
chain.
other
is
H
that
a
In
these
This
if
there
C
C
H
H
H
H
in
are
H
C
is
H
than
chain.
three
C
O
from
there
H
H
C
C
C
C
C
H
H
H
H
H
the
are
groups,
OH OH
H
methanol
functional
it
and
a
H
—OH
triol.
H
pentane-2,3-diol
ethanol,
group
is
at
the
group
groups,
For
can
the
example:
OH
OH
OH
C
C
C
H
H
H
H
propane-1,2,3-triol
can
write
alkyl
the
group
by
general
the
formula
letter
R.
So
for
for
a
homologous
series
halogenoalkanes ,
C
by
H
n
write
RX.
example,
different
16
OH
21
functional
two
is
OH
19
10
ethanol,
—OH
H
C
22
OH
17
9
—OH
If
H
groups
We
an
larger
the
OH
15
8
H
apart
the
H
C
O
OH
13
7
H
propan-2- ol
R
alcohols,
because
alcohols
positions
diol,
OH
all
-1- ol.
H
C
20
10
OH
11
6
O
H
H
C
18
9
10
O
OH
9
5
O
8
H
C
16
C
OH
7
4
14
H
H
C
O
H
7
8
O
12
6
OH
5
3
H
C
H
C
10
5
OH
2
H
C
C
8
4
5
ten
3
6
3
4
rst
Molecular
4
2
the
series.
We
can
RCOR ′
alkyl
write
different
represents
groups.
the
alkyl
groups
general
as
formula
R ′,
of
R″,
a
R″′,
representing
X,
we
can
2n+1
etc.
ketone
For
with
two
Chapter
The
The
will
range of functional
table
need
below
to
shows
some
1
Carbon
compounds:
an
introduction
groups
examples
of
different
functional
groups
you
know.
Homologous
series
General formula
alkanes
Functional
group
Sufx or
RH
prex
-ane
Example
propane, C
H
3
alkenes
RCH=CH
C
2
halogenoalkanes
RX
(where X
is
—F
a
-ene
C
8
propene, CH
CH=CH
3
—Cl
uoro-/
chloro-/
2
bromoethane, C
H
2
alcohols
halogen)
—Br
—I
ROH
—O—H
bromo-/
-ol
ethanol, C
H
2
carboxylic
acids
RCO
H
or
O
RCOOH
-oic
Br
5
iodo-
acid
propanoic
OH
5
acid,
2
C
C
H
2
O
aldehydes
5
H
O
RCHO
COOH
-al
propanal, C
H
2
CHO
5
C
H
ketones
O
RCOR′
-one
propanone,
CH
C
esters
RCO
R
or
C
O
RCOOR′
COCH
3
C
-oate
3
methyl
ethanoate,
2
CH
C
acyl
chlorides
O
3
C
O
RCOCl
COOCH
-oyl
chloride
ethanoyl
CH
C
amines
chloride,
COCl
3
Cl
H
RNH
3
-amine
methylamine,
2
N
CH
H
amides
O
RCONH
NH
3
-amide
2
propanamide,
2
H
C
C
N
H
2
CONH
5
2
H
arenes
C
H
6
R
R
methylbenzene,
5
CH
3
Key points

The functional

Functional
group
groups
(aldehydes),
in
alkenes
containing
—CO—
is C =C.
oxygen
(ketones)
and
are
—OH
—CO
H
(alcohols),
(carboxylic
—CHO
acids).
2

Halogenoalkanes

Amines
have
have
the functional
the functional
group
group
—NH
—X
where X
is
F, Cl,
Br
or
I.
.
2

The
an
general formula
alkyl
of
an
organic
compound
can
be
written
using
R— for
group.
17
2
Hydrocarbons
2.
1
The
alkanes
Alkanes
Learning outcomes
On
completon
should
be
able
of
ths
(general
descrbe
secton,
you
to:
the
reagents
because
between
carbon
no
of
areas
H
there
and
higher
such
as
is
),
only
a
hydrogen.
or
lower
acids
are
very
small
They
electron
and
unreactive
towards
most
chemical
2n+2
alkalis.
are
electronegativity
essentially
density
Details
that
of
can
some
difference
non-polar
be
so
attacked
important
there
are
by
reactions
of
halogenaton,
alkanes
crackng
C
n
reagents

formula
and
combuston
are
given
below.
of
alkanes
Combuston of

explan
the
steps
substtuton
of
n free
alkanes
Alkanes
dioxide

understand
that
mechansms,
n
alkanes
radcal
undergo
and
combustion
water
(in
moement
be
oxygen
For
or
air
to
form
carbon
example:
of
H
4
can
excess
form).
reacton
2C
electrons
in
gaseous
shown
by
(g)
+
13O
10
(g) → 8CO
2
(g) + 10H
2
O(g)
2
cured
butane
arrows
or shhook
notaton.
Incomplete
combustion
H
2C
4
Crackng of
Cracking
alkanes
and
SiO
is
the
and
2
O
2
(g)
9O
A
It
carried
of
cracking
and
Cracking
the
is
+
10H
H
(g)
→ C
28
out
at
of
alkanes
about
is
O(g)
into
shorter-chain
400–500 °C
obtained.
also
a
it
a
For
C
CH
for
H
(g)
+
can
the
C
6
using
example
also
H
2
propene
catalyst
of
3
Halogenaton of
+
3
produces
needed
source
(g)
18
octane
without
because
alkenes
H
8
CH
be
carried
shorter-chain
making
many
out
at
alkanes
chemicals,
(g) →
CH
3
=CH
2
(g)
+
H
2
alkanes
chlorine
are
mixed
in
the
dark
chlorine
are
mixed
in
the
presence
of
can
of
atoms
more
from
substitution
is
replaced
hydrogen
ultraviolet
light).
With
the
Sun),
reaction :
by
atoms
for
plastics.
(g)
and
light
needed
e.g.
2
and
ultraviolet
700–900 °C.
hydrogen:
methane
a
another
.
are
a
A
In
replaced
excess
there
variety
of
products
reaction
in
which
the
by
chlorination
chlorine
is
one
of
atoms
no
reaction.
ultraviolet
be
atom
alkanes,
( hν
light
formed.
or
group
one
or
represents
the
methane:
hν
CH
(g)
+
Cl
4
With
excess
chlorine
chlorine
(g)
→
CH
2
more
Cl(g)
+
HCl(g)
3
and
more
hydrogen
atoms
are
atoms:
CH
Cl(g)
+
Cl
3
CH
(g)
→
CH
2
Cl
2
(l)
+
2
CHCl
Cl
Cl
2
(g)
→
(l)
+
Cl
(l)
+
HCl(g)
2
CHCl
2
3
18
of
400 °C):
ethene
methane
is
catalyst
(g)
When
This
a
(at
4
When
(or
carbon).
3
important
petrol
8CO(g)
(and/or
2
products
tridecane
is
→
decomposition
is
mixture
13
It
(g)
monoxide
alkanes
C
Thermal
carbon
2
thermal
.
+
10
alkenes.
Al
produces
(l)
+
HCl(g)
3
(g)
2
→
CCl
(l)
4
+
HCl(g)
substituted
by
Chapter
Mechansm
Reaction
and
electron
mechanisms
show
the
steps
in
bond
Br
a
moement
breaking
and
bond
:
Br
→
Unit
reactants
1
Study
are
converted
Guide ,
Section
to
intermediates
and
then
to
products
Hydrocarbons
Br
+
Br
b
making
H
when
2
→
Cl

Cl
(see
7.6).
Figure 2.1.1
Homolytic ssion: a
The
bond is split so one electron goes to each
A
bond
can
break
in
two
ways:
homolytic
and
heterolytic
ssion.
atom; b
Homolytic
between
single
ssion:
the
two
covalent
The
two
atoms.
shared
Homolytic
electrons
ssion
in
can
the
bond
occur
in
are
split
many
equally
types
Fishhook arrows show the
direction of movement of each electron
of
bond.
+
The
species
groups
of
formed
atoms
are
with
called
free
unpaired
radicals.
electrons.
Free
The
radicals
unpaired
are
atoms
electron
a
or
Br
:
Br
→
Br:
+
Br
is
b
+
represented
shhook
by
a
arrow
dot.
(see
The
movement
Figure
of
a
single
electron
is
shown
by
unequally.
negatively
positively
curly
ssion:
One
of
the
charged.
charged.
arrow
(see
The
two
atoms
The
The
Figure
+ Cl
2.1.1).
Figure 2.1.2
Heterolytic
→
Cl
a
shared
keeps
other
both
atom
movement
electrons
pairs
becomes
of
a
pair
in
of
the
bond
electrons
electron
of
are
and
split
so
decient
electrons
is
becomes
so
shown
atom; b A curly arrow shows the direction
of movement of the electron pair
is
by
Heterolytic ssion: a The
bond is split so both electrons go to one
a
2.1.2).
H
H
Free
radcal
substtuton
n
H
H
C
Cl
→
H
C
H
The
free
radical
substitution
of
hydrogen
in
alkanes
by
chlorine
occurs
in
three
steps,
e.g.
H
Cl
H
or
Figure 2.1.3
bromine
+
alkanes
the
reaction
of
chlorine
with
The propogation mechanism
methane.
Intaton
H
The
presence
break
by
of
ultraviolet
homolytic
light
causes
the
Cl—Cl
bond
in
chlorine
ssion.
H
Cl
C
→
H
C
H
hv
→
Cl
H
to
Cl• +
Cl
H
Cl•
Figure 2.1.4
The termination mechanism
Propagaton
Free
radicals
methane.
A
are
so
reactive
methyl
free
that
radical,
they
can
,
CH
is
attack
the
formed
relatively
(see
Figure
unreactive
2.1.3).
3
CH
+
Cl•
Key points
→
CH
4
•
+
HCl
3

The
methyl
Chlorine
free
free
radical
radicals
can
are
then
formed
attack
again.
another
So
a
chlorine
chain
form
molecule.
reaction
occurs.
Alkanes

undergo
carbon
Crackng
s
the
•
+
Cl
3
→
CH
2
Cl
+
there
is
excess
chlorine
this
to
water.
of
alkanes
to
Cl•
3
shorter-chan
If
and
thermal
decomposton
CH
combuston
doxde
process
can
continue
until
all
the
alkanes
and
hydrogen
alkenes.
atoms
in
the
methane
have
been
replaced.

CH
Cl
+
Cl•
→
CH
3
CH
Cl•
+
Cl•
+
Cl
2
→
CH
2
Substtuton
the
Cl
2
+
Cl•
and
so
on.
There
bond
and
For
radicals
combine
to
form
a
by
single
molecule
(see
Figure

+
Cl•
→
CH
Cl
or
CH
3
In
•
+
CH
3
•
→
CH
3
stops
nishes
the
when
chain
there
reaction
are
no
in
more
the
propagation
free
or
are
can
two
radicals
left
step.
to
The
react.
ways
break:
n
whch
a
homolytc sson
heterolytc sson.
reacton
mechansms,
of
an
electron
par
CH
3
3
s
This
atom
another.
moement
•
3
nole
one
2.1.4).
example:
CH
of
2

free
replacement
group
Termnaton
T
wo
reactons
HCl
2
reaction
shown
by
moement
by
a
of
a shhook
cured
a
arrow
sngle
and
electron
arrow.
19
2.2
The
alkenes
Alkenes
Learning outcomes
completon
should

be
able
descrbe
wth
of
ths
secton,
you
in
reactive
reactons
hydrogen
general
Section
than
haldes
of
1.1.
formula
Although
alkanes.
electron-rich
to:
the
the
C
H
n
shown
On
have
area
This
which
is
can
alkenes
because
be
.
The
structure
of
ethene
is
2n
are
attacked
non-polar
,
C =C
the
by
they
double
positively
are
bond
more
is
charged
an
reagents.
alkenes
and
Electrophlc
addton
bromne
An

explan
the
steps
noled
n
electrophile
reagent
mechansm
of
is
a
positively
charged
(or
partially
positively
charged)
the
which
attacks
an
electron-rich
area
of
a
molecule.
For
example
electrophlc
+
ions
H
addton
of
hydrogen
bromne
bromde
are
good
electrophiles.
and
to
alkenes.
Most
the
reactions
other
reactions
a
single
product
Addton
When
Exam tips
is
alkenes
is
you
electron
the
tal
where
draw
arrows
moement,
of
an
the
passed
bromoethane
electron
moes from
and
or
the
arrow
electron
head
that
shows
The
Fig
t
moes
addition
from
reactions .
two
In
reactant
addition
molecules
and
no
through
is
mechanism
of
hydrogen
hydrogen
bromide
dissolved
in
an
inert
formed.
=CH
+
HBr
→
CH
2
this
haldes
—CH
3
electrophilic
addition
Br
2
reaction
is
shown
in
2.2.1.
par
H
shows
H
where
wth
2
showng
remember
cured
are
formed
made.
CH
When
is
reactons
ethene
solvent,
of
product
H
H
H
H
+
to.
=C
H
H
H
:Br
H
C
H
H
δ+
H
H
H
δ
Br
Figure 2.2.1
The mechanism of reaction of hydrogen bromide with ethene
+

HBr
is
a
partial

HBr
the

An

At
charge
acts
as
double
H
atom
the
to
The
Br
pair
of
a
from
Br
then
hydrogen
Br
is
a
δ
partial
charge
on
the
H
atom
and
attacking
area
of
high
electron
density
in
a
the
the
double
positively
Br
ion.
atom
The
attacks
bond
gains
H—Br
the
+
in
charged
ethene
control
bond
forms
a
bond
with
carbocation
of
the
breaks
carbocation
electron
pair
in
the
heterolytically.
and
the
addition
product,
formed.
halides
react
in
a
similar
way.
Exam tips
You
A
wll nd
carbocaton
carbon
20
the
s
term
an
carbocation
alkyl
atoms. They
are
δ
atom.
ethene.
form
time
form
ion
the
with
electrophile
to
bromoethane,
Other
on
an
same
HBr
molecule
bond
electron
the

polar
group
often
useful
carryng
when
a
wrtng
sngle
ntermedates
n
about
poste
organc
mechansms.
charge
on
reactons.
one
of
ts
Chapter
Reacton of
When
the
HBr
double
wth other
bond
is
not
alkenes
products
is
formed.
For
quite
the
in
the
reaction
middle
of
Hydrocarbons
Did you know?
of
the
alkene
a
mixture
We
of
2
HBr
with
propene
there
are
can
explan
the
reason for
the
two
drecton
n
whch
hydrogen
bromde
possibilities:
adds
CH
+HBr
CH
2
CH
2
(minor
alkenes
stablty
product)
of
the
n
terms
dfferent
of
the
types
of
3
carbocaton formed.
CHCH
2
to
3
+HBr
CH
CHBrCH
3
(main
product)
most
CH
3
stable
3
+
CH
C
3
The
rule
is
hydrogen
that
the
halide)
more
adds
to
electronegative
the
C
atom
in
atom
the
(the
alkene
halogen
which
is
of
the
connected
to
CH
3
the
least
number
of
H
atoms.
a
tertiary
carbocation
H
Reacton of
alkenes
wth
bromne
+
CH
C
3
Alkenes
react
with
bromine
liquid
to
form
dibromoalkanes
e.g.
CH
3
a
CH
=CH
2
+
Br
2
→
CH
2
Br—CH
2
ethene
secondary
carbocation
Br
2
H
1,2-dibromoethane
+
H
The
mechanism
is
similar
to
that
for
hydrogen
halides
(see
Figure
C
2.2.2).
CH
3
H
H
H
H
a
H
primary
carbocation
least
stable
H
+
=
C
H
H
+
H
H
:Br
C
H
Br
δ +
Br
Br
Br
δ
Br
Figure 2.2.2

The
The mechanism of reaction of bromine with ethene
electrophile
is
the
Br
molecule.
As
the
Br
2
approach
repels
the
each
other
,
electron
the
pair
in
and
ethene
molecules
2
high
electron
the
density
single
Br
in
C =C
the
bond
bond.
2
δ+

This
causes
the
molecule
Br
to
be
polarised
Br
δ
–
—Br
so
that
the
2
δ+
end
Br

An
attacks
electron
the
pair
area
from
of
the
high
electron
double
bond
density
in
ethene
in
the
forms
double
a
bond
bond.
with
δ+
the

At
in
and
Br
the
the
same
to
Br
a
positively
time
the
form
a
charged
other
Br
ion.
Br
carbocation
atom
The
gains
Br—Br
is
formed.
control
bond
of
the
breaks
electron
pair
heterolytically.
2

The
Br
ion
then
attacks
1,2-dibromoethane,
Chlorine
reacts
in
a
is
the
+
carbocation
and
the
addition
product,
formed.
similar
way.
Key points

Most

An
of
the
reactons
electrophle
attacks
an
area

The
double

The
major
addton
s
a
of
bond
of
postely
hgh
n
alkenes
product formed
reacton
or
electron
alkenes
depends
s
are
partly
postely
densty
an
area
when
on
electrophlc
the
an
of
n
a
stablty
charged
reactons.
speces
whch
molecule.
hgh
alkene
addton
electron
undergoes
of
the
densty.
an
electrophlc
carbocaton formed.
21
2.3
More
reactions
Learning outcomes
The
completon
of
ths
secton,
bromine
be
able
to
descrbe
wth
water test for
is
very
hazardous.
So
alkenes
test
for
=
C
C
the
bond
in
we
use
alkenes.
aqueous
bromine
Compounds
(bromine
containing
to:
double

alkenes
you
water)
should
the
bromne
Liquid
On
of
the
reacton
aqueous
of
bromne
alkenes
test
for
bonds
are
also
unsaturated
described
as
being
unsaturated .
So
the
test
is
also
a
compounds.
(bromne
On
addition
of
bromine
water
to
unsaturated
compounds,
the
colour
water)
changes

descrbe
the
reacton
of
from
hot
and
cold

descrbe
wth
manganate(vii)
the
The
reaction
reacton
concentrated
descrbe
the
of
liquid
reacton
hydrogen
of
bromine
water)
is
an
addition
reaction
similar
to
that
to
occurring
bromine
but
a
mixture
of
colourless
addition
products
is
acd
of
alkenes
wth
concentrated
sulphurc
acd
alkenes
(ncludng
is
another
example
of
an
addition
reaction.
For
example,
ethene
the
reacts
producton
the
alkenes
sulphurc
This
wth
of
obtained.
Reacton of

colour
acded
with
potassum
(the
alkenes
colourless.
wth
orange/red-brown
at
room
temperature
to
form
ethyl
hydrogensulphate,
trans fats).
CH
CH
3
OSO
2
H.
3
H
H
H
H
Did you know?
C=C
+
H
In
addton
to
bromne
→
SO
2
H
H
H
4
H
molecules,
H
OSO
H
3
bromne
water
contans
bromc(i)
–
acd,
HOBr,
as
well
as OH
ons from
The
electrophile
is
the
partially
charged
H
atom
in
H
SO
2
the
water.
Bromc(i)
acd
s
polarsed
δ+
H
δ–
HO
δ
+
attacks
so
the
densty
n
— O
— SO
that
area
the
of
the
Br
end
When
hgh-electron
double
H
3
δ+
—Br
4
δ
water
alcohol)
bond rst
is
is
added
formed.
to
the
(The
product
sulphuric
and
acid
the
is
mixture
also
warmed,
ethanol
(an
reformed.)
–
followed
by OH
ons
competng
–
wth
Br
ons
(from
Br
)
to
attack
H
H
C
C
H
H
C
C
the
2
carbocaton
to form CH
BrCH
2
OH.
H
H +
H
2
→
O
H
H +
HOSO
2
H
OSO
H
3
H
H
OH
3
The
overall
from
water
reaction
across
can
the
be
thought
double
CH
=
CH
2
Reacton
The
wth
addition
reaction.
It
of
can
of
as
addition
of
the
H
and
OH
+
H
2
O
→
CH
2
—CH
3
OH
2
hydrogen
hydrogen
also
be
to
an
alkene
regarded
as
is
3
+
example
of
of
a
hydrogen
hydrogenation
or
reduction.
catalyst
→
H
2
an
addition
Ni
CH
=
CH
CH
the
bond:
CH
CH
2
3
CH
2
3
150 °C
propene
Hydrogenation
reactions
Hydrogenation
makes
spreading
digested
qualities.
may
be
Hydrogenation
are
in
not
They
22
some
increase
The
used
oils
fatty
unsaturated
also
commonly
making
are
the
produces
found
pies
levels
and
of
propane
in
or
to
change
fats
acids
(they
nature
cholesterol
which
have
trans
pastries.
less
are
one
fatty
T
rans
the
so
more
(also
2.3.1).
fats
oils
they
released
or
acids
(Figure
in
vegetable
liquid
are
body
,
into
have
when
=
C
C
called
These
harmful
leading
to
margarine.
better
fats
are
double
trans
trans
to
bonds).
fats)
fats
human
heart
which
are
used
health.
disease.
Chapter
a
H
2
Hydrocarbons
H
Did you know?
=
The
dfference
between fats
and
hydrocarbon
C =C
ols
double
s
one
of
state. Ols
are
lqud
at
chain
room
bond
They
temperature
can
be
but fats
classed
as
are
sold.
saturated
b
(no
H
double
(contan
bonds)
one
or
or
unsaturated
more
double
bonds).
=
Saturated fats
tend
to
ncrease
H
cholesterol
hae
been
leels
lnked
Unsaturated fats
Figure 2.3.1
n
to
the
blood
heart
are
and
dsease.
healther for
a A cs fatty acid. The hydrocarbon chains are on the same side of the C=C
bond. b A trans fatty acid. The hydrocarbon chains are on the opposite sides of the double
bond.
you
and
are
cholesterol
Reacton
Potassium
wth
potassum
manganate( vii),
less
lkely
leels
and
to
cause
heart
hgh
dsease.
manganate(vii)
KMnO
,
is
a
good
oxidising
agent.
It
is
4
commonly
solution
called
acidied
concentration
Cold
The
potassium
with
and
the
sulphuric
purple
is
solution
converted
CH
acid.
temperature
acded dlute
alkene
permanganate.
a
colourless
diol
=
CH
2
+
(a
+
reaction
Hot
The
then
can
when
H
2
acded
C=C
also
O
reacted
with
→ CH
2
in
immediately
carboxylic
mixture
acids
of
the
)
3
used
to
alkene
carbon
products
(CH
be
oxidised
or
is
as
a
depends
on
its
with
two
an
—OH
OH—CH
2
alkene.
The
groups).
OH
2
ethane-1,2-diol
test
concentrated
bond
ability
used
manganate(vii)
ethene
This
generally
oxidising
compound
[O]
is
used.
potassum
turns
to
Its
It
by
C
=
CH
2
+
is
broken
the
if
a
and
depending
→
for
is
unsaturated.
manganate(vii)
diol
vii)
on
is
to
the
formed.
ketones,
type
of
The
diol
is
aldehydes,
alkene.
A
example:
(CH
2
)
3
methylpropene
compound
a
manganate(
formed,
4[O]
see
potassum
dioxide
often
to
C
=
O
+
CO
2
+
H
2
O
2
propanone
Note:

We
can

Y
ou
write
[O]
to
represent
the
oxidising
agent,
KMnO
4
do
not
have
to
remember
the
equations
for
these
reactions.
Key points

Bromne

Alcohols
and

Hot
the
water
used
are formed
product
s
concentrated
aldehydes,

Cold

The
to
s
dlute
to
test for
when
then
alkenes
acds
potassum
hydrogenaton
presence
react
hydrolysed
potassum
carboxylc
the
wth
or
carbon
or
ols
may
double
concentrated
bonds.
sulphurc
acd
water.
manganate( vii)
oxdses
alkenes
to
ketones
,
doxde.
manganate( vii)
of fats
wth
of C =C
oxdses
produce
alkenes
to
trans fats
dols.
whch
are
harmful
health.
23
Revision
Answers to
1
Which
all
of
reaction
reson questons
the following
of
hydrogen
A
electrophilic
B
condensation
C
nucleophilic
D
elimination
terms
can
best
chloride
questions
be found on the
describes
with
accompanyng CD.
the
6
a
Explain
propene?

addition
b
the
addition
Which
of
the
statements
below
is
correct
the

nature
of
‘carbocation’
giving
bonding
Limonene
of
2
term
‘electrophile’,
Use
c
the
citrus fruit,
examples
present
their
is the
in
the
chemical
main
and
of
each.
alkenes
to
explain
activity.
contributor to the fragrance
its formula
is
shown
when
below:
CH
2
applied
to
the
reaction
between
propene
and
H
C
C
3
hydrogen
bromide?
A
H—Br
is
B
Br
CH
3
heterolytically
cleaved.
+
is
involved
in
the
initial
attack
of
the

propene
moles
molecule.
C
A
carbanion
intermediate
Propene
undergoes
Which
of
the following
compounds
both
manganate(VII)
would
bromine
be
water
benzene
B
chloroethene
phenol
propane
Which
A
A
are
correct
double
the
Restricted
rotation
bond
limonene
of
reacts
the
with
products
hydrogen
respectively.
chain
hydrogen
and
C.
reacts
of
n
by
hydrocarbon,
mass.
bromine
the
with
A
to
D.
presence
A
has
a
contains
decolourises
produce
hydrogen
A,
of
to
a
two
an
relative
aqueous
compounds
palladium
produce
14.2%
a
catalyst,
gaseous
Calculate
the
molecular
empirical formula
of
A
mass
and
of
56.
hence
bonds?
about
a
prohibits
the
molecular formula.
carbon–carbon
b
double
when
bromine
branched
its

of
a
concerning
a
carbon–carbon
with
solution?
B
statements
number
react
displayed formulae
compound
4
the
will
molecule.
solution
D
that
acid
of
C
reason,
Write
and
and
7
A
a
hydrogenation.
expected to decolourise
potassium
giving
bromine
limonene
formed
3
,
of
is formed.

D
Suggest
possibility
Suggest
the functional
group
present
in
A
and
of
give
a
reason.
stereoisomerism.
c

The
atoms
bonded
to
a
double
bond
Explain
the
production
are
mechanism
of

Double

The
bond
systems
are
electron
double
bond
system
consists
show
the
of
a
bond
and
a
pi
5
ii,
C
i,
D
ii,
iii
iii
iii,
iv
iv
Which
hydrocarbon
series?
A
C
H
2
B
C
2
H
3
C
C
D
C
6
H
4
6
24
10
H
6
in
the
respectively,
movement
of
using
arrows
electrons.
With
reference
to
c
would
suggest
be
which
of
these
preferentially formed.
bond.
e
B
C
sigma
compounds
ii,
and
decient.
d
i,
B
co-planar.
to
A
involved
system
is
a
member
of
the
alkene
Write
the
name
and
displayed formula for
D.
Chapter
8
a
Write
the
displayed formulae for
the
2
Hydrocarbons
–
reson
questons
compounds
A–E
ethane-1,2-diol
B
II
CH
CH
2
2
A
C
ethene
Br
Br
/CCl
2
4
(aq)
2
D
b
n
E
reactions
conditions
c
n
the
state
the
reagents
and
used.
laboratory,
stages;
two
I–III
write
the
reaction
proceeds
III
equations
which
in
two
represent
these
stages.
d
State
two
e
State
the
uses
of
B.
commercial
signicance
of
reaction
I.
3
9
10
cm
of
a
gaseous
hydrocarbon
were
mixed
with
3
100
cm
room
of
oxygen
and
temperature
the
exploded. After
resulting
cooling
gaseous
to
mixture
3
occupied
75
cm
. On
passing
the
gaseous
mixture
3
through
were
be
a
solution
absorbed
oxygen.
of
and
potassium
the
hydroxide,
remaining
(All volumes
were
gas
was
measured
at
30
cm
shown
to
constant
pressure.)
a
Determine
the
molecular formula
of
the
hydrocarbon.
b
The
to
hydrocarbon
produce
two
reacts
displayed formulae
c
With
reference
formed,
be
to
deduce
expected
to
with
hydrogen
compounds. Give
of
the
these
of
these
be formed
in
chloride
names
and
compounds.
respective
which
the
carbocations
compounds
the
greater
would
quantity.
25
3
A variety
3.
1
Alcohols
Learning outcomes
of functional
Classifying
Alcohols
On
completion
of
this
section,
have

be
able
describe
with
the
general
formula
C
H
n
according
to
the
position
of
the
reaction
potassium
of
alcohols
Prmary
potassium
e.g.
alcohols
with

H
the
reaction
the
of
H
The
C
—OH
H
of
sulphuric
describe
may
be
group.
the
group
is
is
attached
attached
to
to
only
a
carbon
one
other
C
H
atom.
H
alcohols
e.g.
alcohols
propan-2- ol
acid
H

that
carbon
acids
reaction
C
alcohols
Secondary
with
They
manganate(VII)
carboxylic
describe
ROH.
functional
dichromate(VI)
H
describe
or
—OH
propan-1- ol
atom

OH
2n+1
the
to:
H
and
alcohols
you
classied
should
groups
iodoform
The
—OH
group
is
attached
to
a
carbon
test.
atom
H
O
that
attached
to
two
other
carbon
H
atoms.
H
is
C
C
C
H
H
H
H
The
—OH
is
in
the
middle
of
the
chain.
water
Tertary
e.g.
alcohols
2-methylpropan-2- ol
out
H
The
—OH
atom
H
C
that
carbon
to
to
three
a
carbon
other
atoms.
in
the
The
—OH
is
at
a
branch
chain.
in
H
C
C
C
H
OH
Oxidation of
Potassium
+
attached
H
point
ethanol
is
attached
H
H
water
group
is
H
H
alcohols
dichromate
(K
Cr
2
excess
oxidising
dichromate()
agent.
During
O
2
this
),
acidied
with
sulphuric
acid
is
a
good
7
reaction
the
orange
dichromate
ions
are
ions
3+
+
concentrated
reduced
acid
heat
Figure 3.1.1
to
Primary
green
ions.
Cr
alcohols
are
oxidised
to
aldehydes
when:
Apparatus for refluxing

the
oxidising

the
aldehyde
agent
is
not
in
excess
and
the
acid
is
fairly
dilute
primary alcohols to carboxylic acids. This
allows heating without loss of ethanol,
is
distilled
off
immediately.
which is volatile. The ethanol vapours
Primary
alcohols
are
oxidised
further
to
carboxylic
acids
when:
condense back into the flask.
Exam tips
An
easy
way
to
distinguish

the
oxidising

the
reaction
agent
is
is
carried
in
excess
out
under
and
the
reux
acid
for
20
is
more
concentrated
minutes
(see
Figure
between
H
H
H
H
O
primary
and
secondary
alcohols
[O]
H
from
their
structure
is
to
C
C
remember
O
[O]
OH
C
H
C
H
oxidation
C
C
oxidation
H
(alcohol
PAL
SAM.
Primary Alcohols
have
the
H
in
H
–
at
the
end
or
Last
H
H
no
agent
+H
group
O
(oxidising
H
excess
—OH
3.1.1).
in
O
2
part
reflux)
ethanol
excess
–
ethanal
ethanoic
acid
reflux)
of
the
chain,
and
Secondary Alcohols
(an
have
of
the
the
—OH
chain.
group
in
the
aldehyde)
(a
carboxylic
acid)
Middle
Figure 3.1.2
Primary alcohols are converted to aldehydes at low concentrations of oxidising
agent. With excess oxidising agent the aldehydes are converted to carboxylic acids.
26
Chapter
Secondary
alcohols
H
are
H
H
H
C
C
C
oxidised
to
ketones.
They
are
not
+
[O]
H
A
variety
of functional
groups
further
.
H
H
OH
oxidised
3
C
C
O
2
H
OH
H
H
propan-2- ol
(a
T
ertiary
the
alcohols
O
H
propanone
cannot
be
oxidised
without
ketone)
breaking
a
C—C
bond
in
alcohol.
Potassium
manganate( vii)
potassium
dichromate.
Reaction of
Alcohols
react

catalysed

reversible

carried
alcohols
with
by
out
acts
under
an
with
carboxylic
sulphuric
as
oxidising
agent
carboxylic
acids
to
form
in
a
similar
way
to
acids
esters.
The
reaction
is:
acid
reux.
O
O
+
H
R
C
+
catalyst
R
R
C
+
H
Did you know?
O
2

Sulphuric
carboxylic
alcohol
acid
primary
For
and
H
3
COOH
+
C
7
H
2
butanoic
acid
may
alcohols
especially
example:
C
acid
also
react
with
ester
OH
Y
C
5
H
3
ethanol
COOC
7
ethyl
H
2
+
H
5
if
excess
reaction
is
produce
alcohol
heated
ethers,
is
to
present
no
O
2
butanoate
the
to
more
than
140 °C.
water
e.g.
For
more
information
about
esters
see
Section
3.6.
2C
H
2
Reaction
Alcohols
the
with
which
—OH
concentrated
have
group
at
react
least
with
one
H
excess
sulphuric
atom
on
the
concentrated
C
form
atom
next
sulphuric
acid
but
on
one
to
OC
5
H
2
+
H
5
O
2
heating
Primary
alcohols
are
oxidised
alkenes.
CH
CH
3
CH
2
OH
→ CH
2
CH=CH
3
propan-1- ol
+
H
2
reaction
is
a
dehydration
a
water
reaction
from
a
in
which
water
to
excess
carboxylic
Secondary
alcohols
are
oxidised
is
ketones.
compound.

Tertiary
alcohols
oxidised
iodoform
without
cannot
be
breaking
the
reaction
C—C
Secondary
agent)
(with
acids.
to
eliminated
and
2
propene
reaction:
aldehydes
oxidising
O

The
H
2
Key points
to
This
→ C
acid

to
OH
5
alcohols,
which
contain
the
group

OH
CH
bond.
Alcohols
acids
C

3
Hot
react
to form
with
carboxylic
esters.
concentrated
sulphuric
dehydrates
alcohols
An
solution
to
acid
alkenes.
H

are
oxidised
by
iodine
in
the
presence
of
sodium
hydroxide.
alkaline
iodine
triiodomethane
formed
precipitates
as
yellow
crystals.
This
is
known
is
iodofor m
test .
One
primary
alcohol,
ethanol,
which
also
used
to
test for
as
alcohols
the
of
The
contains
containing
the
group
the
CH
CH(OH)—
3
CH
CHOH
group
also
gives
this
reaction.
3
27
3.2
Halogenoalkanes
Learning outcomes
Classifying
halogenoalkanes
Halogenoalkanes
On
completion
of
this
section,
be
able
They
describe
primary
may
be
general
classied
formula
according
C
H
X
or
RX
(where
X
is
a
2n+1
to
the
position
of
alcohols.
For
example:
the
halogen
to:
functional

the
n
halogen).
should
have
you
the
and
hydrolysis
group
in
a
similar
way
to
of
primary
secondary
tertiary
halogenoalkane
halogenoalkane
halogenoalkane
tertiary
halogenoalkanes

describe
nucleophilic

describe
the
involved
in
H
H
C
C
H
H
H
C
C
C
H
substitution
H
mechanisms
Cl
H
H
H
H
C
H
H
the
hydrolysis
of
H
primary
and
H
H
I
H
tertiary
H
C
C
C
H
Br
H
H
halogenoalkanes.
chloroethane
2-iodopropane
Nucleophilic
A
nucleophile
decient
atom
is
substitution
a
in
a
electron-decient
Nucleophiles
negative
are
charge.
2-bromo -2-methylpropane
reagent
that
molecule.
donates
A
new
a
pair
covalent
of
electrons
bond
a
either
negatively
Examples
nucleophilic
are
charged
:NH
:OH
substitution

the
nucleophile

the
carbon
is
(:Nu
)
electron
reaction
replaces
the
ions
:CN
the
electron
decient

a
bond

a
bond

curly
electron-
with
the
or
atoms
H
O:
than
decient
pair
carbon
in
a
partial
halogenoalkanes:
because
atom
(X)
halogens
are
more
δ
— Br
C
movement
with
is
from
the
nucleophile
to
the
electron-
atom
is
carbon
an
2
halogen
δ+
electronegative

to
formed
atom.
3
In
is
formed
between
the
nucleophile
and
the
electron
decient-
atom
is
broken
arrows
between
show
the
the
electron-decient
movement
of
the
C
atom
electron
and
the
halogen
pairs.
:Nu
H
H
δ +
R
δ
C
X
R
H
Substitution
Primary
in
Nu
+
:X
H
primary
halogenoalkanes
C
react
halogenoalkanes
with
OH
ions
or
water
to
form
primary
alcohols.
CH
CH
3
CH
2
Cl
+
OH
→ CH
2
Hydrolysis
less
with
effective
water
is
CH
3
1-chloropropane
CH
2
OH
+
Cl
2
propan-1- ol
slower
than
with
OH
ions
because
water
nucleophile.
+
CH
CH
3
28
CH
2
Cl
2
+
H
O
2
→
CH
CH
3
CH
2
OH
2
+
H
+
Cl
is
a
Chapter
Ethanol
is
not
with
mix
used
as
a
solvent
aqueous
in
these
reactions
since
halogenoalkanes
do
3
mechanism
for
variety
Figure
groups
Did you know?
the
reaction
of
bromoethane
with
OH
ions
is
the
nucleophilic
substitution
shown
reaction for
in
of functional
solutions.
n
The
A
a
primary
3.2.1.
halogenoalkane,
an
intermediate
chemists
think
is formed
as
that
the
:OH
H
H
H
δ +
H
C
C
H
H
C—Br
H
δ
bond
breaks
and
the C—OH
bond forms.
Br
H
C
:Br
H
H
H
C
C
H
H
H
Br
H
OH
Figure 3.2.1
Nucleophilic substitution in a primary halogenoalkane. The OH
ion attacks
δ+
the C
at the same time as the C—Br bond breaks.
ntermediates
In
this
mechanism:
isolated,
like
this
have
not
been
however.
δ+

the

a
new
as

OH
(nucleophile)
covalent
the
the
ion
C—Br
Br
atom
bond
bond
takes
donates
between
C
a
pair
and
of
—OH
electrons
is
formed
to
the
C
atom
at
the
same
time
breaks
both
electrons
in
the
C—Br
bond
and
leaves
as
a
Did you know?
ion.
Br
The
Substitution
in tertiary
mechanism for
halogenoalkane
halogenoalkanes
S
2.
primary
hydrolysis
(Substitution
is
called
nucleophilic
N
T
ertiary
halogenoalkanes
react
with
OH
ions
or
water
to
form
tertiary
2nd
order). The
rate-determining
alcohols.
step
involves
two
species
–
CH(CH
CH
3
)ClCH
3
+
OH
→
CH
3
CH(CH
3
2-bromo -2-methylpropane
)(OH)CH
3
+
(halogenoalkane
Cl
2-methylpropan-2- ol
mechanism for
halogenoalkane
two -step
mechanism
for
).
3
The
The
and OH
this
reaction
is
shown
in
Figure
tertiary
hydrolysis
is
called
3.2.2.
S
1.
(Substitution
nucleophilic
1st
N
order.) The
CH
CH
3
3
involves
C
Br
CH
one
species
(halogenoalkane
fast
+
3
step
CH
3
slow
CH
rate-determining
C
:OH
CH
3
C
OH
+
Br
3
only).
CH
CH
3
Figure 3.2.2
CH
3
3
Nucleophilic substitution in a tertiary halogenoalkane. In the rst step a
ion
tertiary halogenoalkane ionises to form a carbocation. In the second step the OH
attacks the carbocation.
Key points
In
this
mechanism:


the
C—Br
bond
breaks
by
heterolytic
ssion.
The
bromine
atom
A
nucleophile
donates
both
electrons
in
the
C—Br
bond
to
become
is
a
a
pair
of
an
intermediate
carbocation
is
formed
with
a
full
charge
on
the
atom
an
to form
the
new
covalent
bond.
atom


to
Br
a
carbon
that
electrons
electron-decient

reagent
takes
OH
ion
(nucleophile)
attacks
the
Hydrolysis
of
primary
carbocation
halogenoalkanes
occurs
in
a
–

a
new
bond
is
formed
by
the
electron
pair
donated
by
the
OH
ion.
single
step.
t
involves
both
the
–
halogenoalkane
Chloro-,
bromo-
and
iodoalkane
hydrolysis

Hydrolysis
of
and OH
tertiary
halogenoalkanes
The
reactions
are
similar
in
each
case.
The
rate
of
hydrolysis
is
related
bond
strength
of
the
carbon–halogen
2
F
C
5
H
2
Cl
C
5
route
which
by
a
involves
bond.
(i)
H
C
occurs
to
two-step
the
ions.
H
2
Br
C
5
H
2
ionisation
of
the
I
5
halogenoalkane
(ii)
attack
by
an
–
–

faster
rate

weaker
of
hydrolysis
by
OH
→
OH
ion
on
a
carbocation
intermediate.
bond
energy
of
C—halogen
bond
→
29
3.3
Carbonyl
Learning outcomes
compounds
Structure
Aldehydes
On
completion
should
be
able
of
this
section,
describe
to:
the

aldehydes
structure
and
and
names of
ketones
both
aldehydes
contain
the
and
carbonyl
ketones
group.
you
In
aldehydes
atom

and
the
bonded
to
carbonyl
carbon
atom
has
at
least
one
hydrogen
it.
of

ketones
In
ketones
the
carbonyl
carbon
atom
has
two
carbon
atoms
bonded
to
it.

describe
the
compounds
reactions
with
of
Brady’s
carbonyl
a
reagent,
b
C
c
R
reagent
and
R
O
C
Tollens’
O
C
O
Fehling’s
H
R

solution
Figure 3.3.1

describe
the
compounds
reaction
with
of
acidied
The
potassium
a The carbonyl group; b An aldehyde; c A ketone
carbonyl
table
below
gives
the
names
of
some
aldehydes
and
ketones.
manganate(VII).
Name of
Structural
Name of
aldehyde
formula
ketone
Structural formula
methanal
HCHO
propanone
CH
COCH
3
ethanal
CH
CHO
butanone
CH
3
3
CH
3
COCH
2
3
Did you know?
propanal
ery
are
small
amounts
present
in
blood
of
CH
and
a
suffering from
higher
Excess
propanone
through
diabetes
concentration
the
‘acetone
can
than
be
lungs. This
CHO
pentan-2-one
CH
2
CH
3
CH
2
COCH
2
3
urine.
butanal
People
CH
3
propanone
is
CH
(CH
3
have
)
2
CHO
pentan-3-one
CH
2
CH
3
COCH
2
CH
2
3
usual.
exhaled
called
Testing for the
carbonyl
group
breath’.
We
add
a
DNPH)
present,
by
solution
to
a
the
of
deep
orange
recrystallisation
particular
of
particular
for
an
or
or
is
formed.
its
If
melting
present.
ketone
If
This
has
a
is
an
we
aldehyde
purify
point,
we
because
melting
the
can
each
point
or
or
ketone
is
precipitate
identify
the
DNPH
which
is
compound.
Distinguishing
between
Usng Tollens’
reagent
T
ollens’
is
reagent
(2,4-dinitrophenylhydrazine
compound.
determine
ketone
aldehyde
that
reagent
carbonyl
precipitate
and
aldehyde
derivative
Brady ’s
suspected
an
aldehydes
(sler
aqueous
and
ketones
mrror test)
solution
of
silver
nitrate
in
excess
+
ammonia.
This
contains
the
)
[Ag(NH
3
]
ion.
2
Aldehydes
When
warmed
carboxylic
‘mirror ’
is
carefully
acids.
seen
The
on
with
silver
the
T
ollens’
complex
side
of
RCHO
the
+
reagent,
ions
are
aldehydes
reduced
to
are
oxidised
silver
.
A
to
silver
test-tube.
[O] →
RCOOH
+
[Ag(NH
)
3
Note:
when
complex,
30
we
equations
can
use
]
+
to
→
Ag
+
2NH
2
involving
[O]
e
3
the
oxidation
represent
the
effect
of
of
carbon
the
compounds
oxidising
are
agent.
Chapter
Ketones
Ketones
3
A
variety
groups
Did you know?
give
no
reaction
with
T
ollens’
reagent
(the
mixture
remains
The
colourless).
This
is
because
ketones
cannot
be
oxidised
to
carboxylic
tests for
reagent
solution
Fehlng’s
and
depends
using
on
Fehling’s
the
reduction
of
soluton
complex
Fehling’s
aldehydes
acids.
Tollens’
Usng
of functional
solution
is
formed
by
mixing
two
solutions:
Fehling’s
A
(which
Section
ions
(see
13.4).
Unit 1 Study Guide,
Many
chemical
tests
2+
contains
aqueous
complexing
Cu
reagent
ions)
and
an
and
Fehling’s
B
(which
contains
a
and
alkali).
some
analysis
aspects
by
of
quantitative
spectroscopy
the formation
of
depend
complex
ions
on
(see
Aldehydes
Section
When
warmed
with
Fehling’s
solution,
aldehydes
are
oxidised
9.4).
to
2+
carboxylic
solution
acids.
The
changes
to
blue
an
colour
of
orange-red
the
Cu
ions
precipitate
of
in
the
copper(
Fehling’s
i)
oxide.
2+
The
Cu
ions
copper( i)
oxidise
the
aldehyde
and
are
themselves
reduced
to
the
state.
Ketones
Ketones
blue).
give
This
Usng
no
is
reaction
because
potassum
with
Fehling’s
ketones
cannot
solution
be
manganate(vii)
(the
oxidised
or
to
mixture
remains
carboxylic
acids.
potassum
dchromate(vi)
In
Section
3.1
we
saw
that
manganate( vii)
potassium
alcohols
can
(potassium
be
oxidised
by
permanganate)
acidied
or
potassium
dichromate( vi).
In
each
and
We
case
using
can
from
an
aldehyde
reux,
also
use
the
was
rst
aldehyde
these
is
oxidising
formed.
With
converted
agents
to
to
a
help
excess
oxidising
carboxylic
us
agent
acid.
distinguish
aldehydes
ketones.
Aldehydes
When
are
reuxed
oxidised
with
to
excess
carboxylic
CH
CH
3
acidied
acids.
For
CHO +
potassium
manganate(
vii),
aldehydes
Key points
example:
[O]
→ CH
2
CH
3
propanal
COOH
2

propanoic
Aldehydes
the
The
purple
likely
colour
turns
of
the
brownish.
potassium
This
is
manganate(
because
the
vii)
and
ketones
contain
acid
decolourises
manganate(
vii)
ions
or
more

carbonyl
Aldehydes
group, C=O.
are
oxidised
to
are
carboxylic
acids
but
ketones
are
2+
reduced
to
ions
Mn
(very
pale
pink)
or
MnO
(brown).
2
When
reuxed
with
excess
acidied
potassium
not.
dichromate(
vi),
the

aldehyde
is
again
oxidised
to
the
carboxylic
acid
having
the
same
Brady’s
to
of
carbon
atoms.
The
orange
colour
of
the
potassium
reagent
can
be
used
number
identify
a C=O
group. The
dichromate
orange
crystals formed
have
3+
(oxidation
number
+6)
changes
to
the
green
colour
of
Cr
ions.
Ketones
characteristic
melting
depending
the
compound
Ketones
give
no
dichromate( vi).
conditions
are
reaction
This
very
is
with
potassium
because
severe
and
ketones
C—C
manganate(
cannot
bonds
are
be
vii)
or
oxidised
on
points
carbonyl
used.
potassium
unless
the

Aldehydes form
on
broken.
warming
but

ketones
do
Fehling’s
silver
mirror
on
reagent
not.
Aldehydes form
precipitate
a
with Tollens’
an
orange
warming
solution
but
with
ketones
do
not.
31
3.4
More
about
Learning outcomes
carbonyl
Nucleophilic
The
On
completion
of
this
section,
C=O
bond
be
able
in
describe
reactions
of
aldehydes
the
and
oxygen
ketones
atom.
The
the
reaction
of
closer
to
the
oxygen
describe
polarised
due
pairs
in
to
the
the
high
bond
are
atom.
carbonyl
δ +
compounds

is
electron
to:
drawn

addition
you
electronegativity
should
compounds
the
with
mechanism
δ
C
NaCN/HCl
O
of
δ+

nucleophilic
addition
reactions
The
C
atom
in
the
carbonyl
group
is
open
to
attack
by
nucleophiles
of
such
as
and
:CN
HSO
4
carbonyl

describe
compounds
the
carbonyl
reduction
compounds

A
negatively

The
hydride
addition
hydrogen
of
platinum
intermediate
is
formed.
of
by
intermediate
and
reacts
with
a
hydrogen
ion
(from
dilute
acid
or
lithium
water
aluminium
charged
present
in
the
reaction
mixture).
by
using
:Nu
a
catalyst.
R
R
δ +
Nu
R
(H
C
Nu
+
δ
O
from
solvent)
C
R
C
O:
R
R
O
H
+
H
δ+
Figure 3.4.1
A nucleophile :Nu
attacks the C
+
atom, a H
ion from the solvent attacks
the negatively charged intermediate. (Note: R’ can be an alkyl group or hydrogen.)
The
the
overall
reaction
presence
of
is
an
hydrogen
addition
ions
has
reaction
added
because
across
the
the
nucleophile
C =O
bond,
in
e.g.
with
ethanal:
CH
CH
3
Nu
3
+
C
O
+
:Nu
+
H
Nucleophilic
When
sodium
C
→
H
H
addition of
cyanide
is
O
hydrogen
acidied,
the
cyanide
poisonous
gas
+
NaCN
The
:CN
ion
The
overall
in
the
reaction
CH
weak
with
+
acid
H
HCN
acts
as
+
a
CH
+
HCN
CH
mechanism
ketones
is
of
shown
the
CN
2
→
C
H
H
The
Na
3
O
reaction
of
hydrogen
cyanide
OH
with
aldehydes
below.
a
:CN
R
R
δ +
CN
R
δ
CN
+
H
C
O
H
C
H
C
O:
O
H
H
+
H
b
:CN
R
R
δ +
CN
R
δ
CN
+
H
C
R
O
C
R
C
O:
R
+
H
Figure 3.4.2
32
formed:
nucleophile.
2
C
is
is:
CH
3
HCN
+
→
HCN
propanal
H
Reaction of HCN with a an aldehyde; b a ketone
O
H
and
Chapter
In
each
3
A
variety
of functional
groups
case:
δ+

the
C
atom
in
the
carbonyl
group
is
attacked
by
the
nucleophile
–
:CN

a
negatively

the
charged
intermediate
present
in
the
intermediate
reacts
reaction
with
a
is
formed
hydrogen
ion
(from
dilute
acid
or
water
mixture).
Did you know?
The
cyanide
t
not
is
a
ion
is
danger
present
to
us,
in
plants
however,
such
since
as
it
is
sorghum,
usually
clover
present
and
in
cassava.
very
low
concentrations.
Reduction of
Lithium
aldehydes
aluminium
hydride
and
(lithium
ketones
tetrahydridoaluminate),
LiAlH
,
is
4
often

used
as
a
Aldehydes
reducing
are
agent
reduced
to
in
organic
primary
reactions.
alcohols.
For
example:
H
H
CH
CH
3
+
2[H]
CH
2
3
C
2
O
H
propanal

Ketones
are
reduced
propan-1- ol
to
secondary
alcohols.
CH
For
example:
CH
3
3
C
+
O
2[H]
C
CH
3
CH
H
3
propanone

The
reaction

The
nucleophile
with
propan-2- ol
LiAlH
is
also
a
nucleophilic
addition.
4
–
is
the
hydride
ion,
H
,
arising
from
the
LiAlH
.
4

The
reaction
presence
Note:
We
of
can
a
can
also
be
platinum
use
[H]
to
carried
catalyst
represent
out
(the
the
by
adding
hydrogen
mechanism
hydrogen
here
from
is
the
in
the
different).
reducing
agent.
Key points

Carbonyl
cyanide

The
compounds
undergo
nucleophilic
addition
reactions
with
the
ion.
cyanide
electrons
to
ion
acts
as
a
the
partially
nucleophile
positively
because
charged
it
donates
carbon
atom
a
lone
in
pair
of
aldehydes
and
ketones.

Aldehydes
or

Ketones
or
are
hydrogen
are
hydrogen
reduced
using
a
reduced
using
a
to
primary
platinum
to
secondary
platinum
alcohols
by
lithium
aluminium
hydride
by
lithium
aluminium
hydride
catalyst.
alcohols
catalyst.
33
3.5
Carboxylic
Learning outcomes
acids
Introduction
The
On
completion
should
be
able
of
this
section,
functional
group
in
carboxylic
acids
is
you
to:
O

describe
the
carboxylic
hydroxide,
reactions
acids
with
describe
the
carboxylic
The
and
describe
the
with
table
shows
of
reaction
with
—COOH
names
and
formulae
of
some
carboxylic
acids.
Structural formula
acid
HCOOH
of
PCl
,
acid
CH
COOH
3
PCl
3
and
the
Name
methanoic
acids
or
alcohols
ethanoic
carboxylic
H
2
metals
(esterication)

—CO
sodium
reaction
acids
or
C
sodium
hydrogencarbonate

of
5
SOCl
2
propanoic
acid
CH
CH
3
butanoic
acid
CH
COOH
2
CH
3
CH
2
COOH
2
Exam tips
The
When
naming
carboxylic
carboxylic
acid
group
is
polarised
as
shown
below:
δ
acids,
O
remember
that
the
number
δ +
of
C
δ +
δ
carbon
atom
atoms
of
the
includes
—COOH
the
carbon
group.
δ+

The
C
atom
can
be
attacked
by
weak
nucleophiles
in
the
presence
of
+
ions.
H
δ

The
O
atom
can
be
attacked
by
positively
charged
species
such
as
+
H
δ+

Did you know?
Many
in
carboxylic
nature.
acid)
is
H
Acidic
acids
Methanoic
an
The
are found
acid
irritant found
(formic
in
atom
lost
when
properties of
Carboxylic
the
is
acids
are
weak
a
carboxylic
carboxylic
acids.
The
acid
behaves
as
an
acid.
acids
position
of
equilibrium
is
over
to
left.
bee
+
CH
stings
made
and
by
in
ants.
distilling
Methanoic
reactions
acid
of
t
was
the
gives
bodies
some
aldehydes
of
of
the
—CHO
H
O
Y CH
2
COO
+
H
3
O
3
ethanoic
ethanoate
acid
ion
the
because
group.
+
ants.
it
They
contains
COOH
3
originally
with
are
strong
sodium
enough
hydroxide,
Reacton
wth
Carboxylic
acids
and
acids
sodum
react
to
show
carbonates
typical
and
acid
reactive
properties,
e.g.
hydroxde
with
sodium
hydroxide
to
form
the
sodium
water
.
+
CH
CH
3
COOH

The
salts
+
NaOH
→
CH
2
of
CH
3
propanoic
the
acid
sodium
carboxylic
acids
are
COO
HCOO
Na
called
34
+
H
O
2
propanoate
carboxylates.
+
is
sodium
methanoate, CH
COO
3
ethanoate.
Na
2
+

reaction
metals.
Na
is
sodium
salt
Chapter
Reacton
wth
Carboxylic
acids
3
A
variety
of functional
groups
metals
react
with
sodium
to
form
a
metal
salt
and
hydrogen.
+
2CH
COOH +
2Na
→
2CH
3
ethanoic
Other
reactive
COO
Na
+
H
3
metals
acid
also
2
sodium
form
salts,
e.g.
ethanoate
magnesium
ethanoate,
2+
(CH
COO
)
3
Mg
2
Reacton
wth
Carboxylic
acids
water
and
hydrogencarbonates
react
carbon
with
dioxide
carbonates
are
and
and
carbonates
hydrogencarbonates.
A
salt,
formed.
+
HCOOH
+
→
NaHCO
HCOO
Na
+
H
3
methanoic
Reaction of
Carboxylic
(usually
reux
acids
react
concentrated
to
distilled
an
sodium
carboxylic
prevent
off
the
when
esterification
with
loss
the
acids
alcohols
sulphuric
of
+
CO
is
2
methanoate
with
in
acid).
volatile
reaction
O
2
acid
the
alcohols
presence
The
of
reactants
alcohols
complete.
and
This
an
are
esters.
type
acid
catalyst
heated
The
of
under
esters
reaction
is
are
called
reaction.
O
O
+
H
OH +
CH
H
3
Figure 3.5.1
2
CH
5
C
+H
H
3
2
5
O
2
The ester, ethyl ethanoate, is formed by the reaction of ethanol with
ethanoic acid. The dashed line shows the bonds that are broken during the reaction.
The
in
reaction
which
been
can
two
eliminated.
elimination
also
be
molecules
described
have
Another
reaction.
way
This
is
as
reacted
of
a
condensation
together
describing
because
the
and
the
a
reaction
small
reaction
ethanol
–
a
reaction
molecule
is
as
molecule
an
rst
has
addition–
forms
an
δ+
addition
product
Reaction
by
attacking
with
PCl
,
the
PCl
5
Carboxylic
acids
phosphorus( v)
.
SOCl
The
react
products
or
are
of
the
group.
2
with
sulphur
called
—COOH
and SOCl
3
rapidly
chloride
atom
C
phosphorus(
dichloride
acid
iii)
chloride,
oxide
chlorides
(acyl
(thionyl
chloride),
chlorides).
Acidic
2
fumes
of
HCl
are
also
COOH
CH
produced.
+
PCl
+
SOCl
3
3
note:
CH
→
CH
and
SOCl
POCl
+
SO
should
be
+
HCl
+
HCl
2
ethanoyl
3
+
3
COCl
3
acid
PCl
COCl
3
2
ethanoic
Safety
→
5
COOH
CH
chloride
used
in
a
fume
cupboard.
2
Key points
Exam tips

Carboxylic
acids
are

Carboxylic
acids
react
with
sodium
weak
acids.
with
sodium
hydrogencarbonate
hydroxide
to form
a
to form
salt,
a
carbon
salt
and
dioxide
water
and
and
water.
You
do
not
have
equations for
phosphorus

Carboxylic
acids
react
with
reactive

Carboxylic
acids
react
with
alcohols

Carboxylic
acids
react
with
PCl
metals
to form
a
salt
and
3
hydrogen
chloride.
PCl
and
5
the
chlorides
or
of
the
thionyl
with
carboxylic
acids. You
esters.
should
,
learn
reactions
hydrogen.
chloride
to form
to
the
SOCl
to form
acid
chlorides
and
fumes
know,
are
however,
given
off
that
and
acidic
that
acid
2
chlorides
are formed.
35
3.6
Esters
Learning outcomes
Introduction
Esters
On
completion
should

be
name
able
of
this
section,
have
the
general
structure
you
to:
esters
O
and
write
R
their
ester
link
C
O
R
structural formulae

describe
from

the formation
of
esters
from
from
acid
alcohol
alcohols
describe
the
catalysed
acid-
and
hydrolysis
base-
of
The
—COO—
The
naming
group
is
often
called
an
ester
link
(see
Section
6.2).
esters.
alcohol

The

The
- oic
used
of
esters
to
make
name
begins
name
ends
acid
is
is
based
on
the
name
of
the
carboxylic
acid
and
them.
with
with
changed
the
the
to
alkyl
part
(or
aryl)
coming
group
from
from
the
the
alcohol.
carboxylic
acid,
but
- oate.
O
CH
C
3
O
CH
=
methyl
ethanoate
3
methyl
ethanoate
(from
(from
ethanoic
methanol)
acid)
Exam tips
The
Be
careful
sure
that
–oate
The
with
you
parts
part
of
naming
don’t
the
the
get
wrong
name
esters.
the
way
table
the
comes rst
alkyl
relating
acid
(the
–oate
and
the
comes
some
and
Structure of
of
different
ester
esters.
Name of
ester
to
the
CH
CH
CH
2
COOCH
2
methyl
butanoate
3
part from
second).
HCOOCH
CH
2
CH
CH
2
COOCH
3
propyl
methanoate
3
CH
2
ethyl
ethanoate
ethyl
benzoate
3
COOCH
CH
2
water
names
round.
3
alcohol
gives
Make
3
out
condenser
colder
CH
here
water
COO
phenyl
3
in
Hydrolysis of
Hydrolysis
is
speeded
by
Esters
ester
sulphuric
ethanoate
+
up
are
the
esters
breakdown
reacting
hydrolysed
a
by
of
a
compound
compound
heating
with
the
with
either
ester
water
.
an
under
acid
reux
It
or
is
an
with
often
alkali.
an
acid
or
a
base.
acid

Heating

The

Reux
is
acid
necessary
or
alkali
because
acts
as
a
the
reaction
is
slow.
catalyst.
heat
and
Figure 3.6.1
refluxing
36
is
necessary
alcohol.
The
to
prevent
vapours
rise
the
and
loss
of
then
the
volatile
condense
on
vapours
the
of
colder
the
Acid hydrolysis of an ester by
the
condenser
.
They
then
drip
back
into
the
ask
(Figure
ester
parts
3.6.1).
of
Chapter
Acd
3
A
variety
of functional
groups
hydrolyss
Exam tips
This
is
the
carboxylic
reverse
of
the
preparation
of
an
ester
from
an
alcohol
and
a
You
acid.
may nd
purposes

The
ester
is
heated
with
diluted
sulphuric
The

So
reaction
is
‘mind

A

For
ester
is
carboxylic
an
the
ester
ester
a
revision
‘spider
showing
all
diagram’
the
reversible.
not
acid
fully
and
hydrolysed.
an
alcohol
between
functional
are
This
formed.
will
groups
help
synthesise
of
draw
map’
reactions
the
useful for
acid.
or

to
it
RCOOR ′
and
the
the
carboxylic
alcohol
from
acid
the
arises
—OR
from
the
RCO—
a
you
various
this
to
see
particular
section.
how
you
can
compound
part
by
part.
a
three-
or four-stage
starting from
compound.
O
the
in
another
n
your
route
particular
spider
diagram
O
+
H
CH
C
+
H
3
catalyst
you
O
CH
2
C
+
C
3
H
2
should
include
halogenoalkanes,
O
C
5
ketones,
Figure 3.6.2
Alkalne
In

the
carboxylic
acids
and
esters.
Acid hydrolysis of ethyl ethanoate
hydrolyss
base-catalysed
The
alcohols,
aldehydes,
OH
H
2
alkenes,
OH
5
ester
is
hydrolysis
heated
with
of
an
aqueous
ester:
sodium
hydroxide
(or
other
suitable
base).

The
reaction

The
ester

An

For
is
alcohol
an
not
fully
and
ester
RCO—
is
part
reversible.
the
salt
RCOOR ′,
of
Did you know?
hydrolysed.
the
of
a
the
ester
carboxylic
salt
and
of
the
the
acid
are
carboxylic
alcohol
from
Apart from
their
flavourings
and
acid
the
arises
—OR
from
esters
can
in
be
perfumes,
used
insect
damage.
to
some
reduce
part.
–
Some
they
esters
are
act
given
as
out
O
naturally
CH
uses
the
pheromones
O
common
formed.
+
C
NaOH
CH
3
+
C
C
3
H
2
by female
insects
to
attract
OH
5
the
males.
Spraying
crops
with
+
O
C
CH
COOCH
3
5
synthetic
+
+
CH
2
ethyl
Na
O
H
2
CH
NaOH
COO
Na
males
+
CH
3
3
CH
3
sodium
ethanoate
ethanoate
pheromones
and
they
do
confuses
the
not nd females
OH
2
to
ethanol
mate
with.
So fewer
offspring
are
produced.
Figure 3.6.3
The
Alkaline hydrolysis of ethyl ethanoate
sodium
react
with
sodium
Some
salt
of
sodium
the
carboxylic
hydroxide
(see
acid
is
formed
Section
3.5).
because
Alcohols
carboxylic
do
not
acids
react
with
hydroxide.
more
equatons for
HCOOCH
+
ester
H
3
methyl
CH
O Y
COOCH
2
HCOOH
+
CH
2
+
3
methanoic
H
OH
3
methanoate
CH
3
methyl
hydrolyss
O Y CH
2
CH
3
propanoate
acid
COOH
methanol
+
CH
2
Key points
OH

3
propanoic
acid
methanol
Esters
are formed
alcohols

When
with
esters
by
refluxing
acid.
are
hydrolysed
+
CH
COOCH
3
CH
2
CH
2
+
NaOH →
3
CH
COO
Na
+
3
CH
CH
3
CH
2
OH
2
by
propyl
ethanaote
sodium
ethanoate
acids,
the
products
are
a
propanol
carboxylic
acid
and
an
alcohol.
+
HCOOCH
CH
2
ethyl
+ NaOH →
HCOO
Na
3
methanoate
+
CH
CH
3
sodium
methanoate
OH
2
ethanol

When
base,
a
esters
the
are
hydrolysed
products
carboxylic
acid
are
and
the
an
by
salt
a
of
alcohol.
37
3.7
Saponification
Learning outcomes
On
completion
should
be
able

describe

understand
of
this
Fats
section,
and oils

Fats
to:

Long-chain

The
and
oils
are
esters
of
long-chain
carboxylic
acids
with
glycerol.
only
carboxylic
difference
acids
are
between
a
sometimes
fat
and
an
called
oil
is
fatty
that
a
acids.
fat
is
solid
and
saponication
an
by
biodiesel
you
that
biodiesel
can
oil
is
a
liquid
at
room
temperature.
be

made
and
The
chain
lengths
of
the
fatty
acids
(carboxylic
acids)
in
fats
are
from
transesterication
12–18
carbon
atoms.
reactions


understand
the
basic
transesterication.
principles
The
fatty
acids
in
fats
can
be
the
same
or
different.
of
Figure
make
3.7.1
a
−
shows
triglyceride
glycerol
by
HOOC
OH
an
reacting
with
esterication
three
fatty
acid
molecules
to
reaction.
−
−
−
−
−
−
O OC
−
H
−
OH
+
HOOC
O OC
−
+
3 O
H
−
OH
HOOC
fatty
glycerol
O OC
−
a fat
acids
water
Figure 3.7.1
represents
the alkyl side chain of the fatty acid)
Saponification
Saponification
and
is
the
process
of
making
soaps
by
the
hydrolysis
of
fats
oils.

Soaps
are
metal

Soaps
are
made

Sodium

The
by
hydroxide
products
(soap)
salts
and
are
of
long-chain
boiling
fats
hydrolyses
the
sodium
carboxylic
with
the
sodium
three
salts
of
acids.
or
ester
potassium
links
long-chain
in
hydroxide.
fats.
carboxylic
acids
glycerol.
heat
fat
Figure
3.7.2
(or
oil)
shows
+
sodium
the
hydroxide
hydrolysis
of
a
fat
→ soap
(trigyceride)
+
glycerol
with
sodium
hydroxide.
a
C
H
17
C
H
17
C
C
2
H
17
COOCH
+
3NaOH
35
H
17
COOCH
35
C
H
17
COOCH
35
C
2
glyceryl
stearate
+
(a fat)
sodium
hydroxide
HOCH
2
COONa
+
HOCH
+
HOCH
35
H
17
COONa
35
COONa
35
sodium
(a
2
stearate
+
glycerol
soap)
b
COONa
COO
COO
+ 3NaOH
COONa
COONa
COO
fat
Figure 3.7.2
+
sodium
hydroxide
soap
+
HO
HO
glycerol
Soaps are formed when fats or oils are hydrolysed with sodium hydroxide;
a The hydrolysis of a fat; b A simplied diagram of saponication (
alkyl side chain of the fatty acid)
38
+
HO
represents the
Chapter
supply
out.
For
A
of
petroleum
used
as
a
basis
for
fuels
will
eventually
this
reason
fuels.
vegetable
of functional
groups
r un
The
making
variety
Did you know?
Biodiesel
The
3
scientists
Biodiesel
oils
from
is
plants
a
have
fuel
or
been
for
fats
tr ying
diesel
from
to
 nd
engines
animals.
It
other
that
is
is
ways
made
made
cleaning
action
of
soap
is
due
to
of
the
attraction
the
soap for
of
different
parts
of
from
grease
and
water. The
by
ionic
‘head’
is
attracted
to
water
and
transesteri cation.
the
T
ransesterification
different
ester
and
is
the
reaction
different
of
alcohol.
an
ester
The
with
alkyl
an
group
alcohol
from
to
the
form
hydrocarbon
‘tail’
is
attracted
to
grease.
a
alcohol
water
replaces
the
alcohol.
The

heat

a
is
alkyl
group
reaction
in
is
the
slow
ester
which
from
a
different
ionic
‘head’
so:
required
catalyst
is
used
to
speed
up
the
process.
–
e.g.
originates
sodium
methoxide,
O
CH
Acids,
alkalis
or
hydrocarbon
alkoxides
+
Na
‘tail’
are
used
as
catalysts.
3
grease
O
O
catalyst
C
H
2
COC
5
ester
Figure 3.7.3
H
6
+
CH
13
OH
C
3
1
H
2
alcohol
1
COCH
5
+
C
3
ester
H
6
2
OH
13
alcohol
2
Transesterication. An ester reacts with an alcohol to form a different ester
and a different alcohol.
T
ransesterication
more
complex
usually
results
in
a
simpler
ester
being
formed
from
a
ester
.
grease
CH
COOC
3
H
12
+
CH
25
OH
→
CH
3
COOCH
3
+
C
3
H
12
off
dodecanyl
The
has
ester
a
is
lower
undergo
ethanoate
more
+
useful
viscosity
methanol
as
and
a
transesterication,
hydroxide
where
fuel
burns
hydrolysis
→
because
more
especially
also
methyl
it
has
easily.
in
ethanaote
a
Fats
the
lower
and
of
surface
dodecanol
molar
oils
presence
+
lifted
OH
25
can
mass.
So
it
also
sodium
occurs.
Exam tips
CH
– O
2
CH
CR
CH
2
– O
O
3
CR
+
3CH
2
CH
OH
3
O
3
CR
CH
2
OH
2
CR
+
You
CHOH
do
not
equations
CH
– O
2
CR


CH
2
O
3
CR


CH
2
to
remember
the
in
this
section. You
should,
OH
2
however,
fat
know:
glycerol
1
Figure 3.7.4
have
2
the
basic
structure
of
a
triester
Transesterication and hydrolysis of a fat. A triglyceride reacts with
(fat)
methanol to form esters of lower molar mass and glycerol. R, R and R represent alkyl
groups with 12–18 carbon atoms.
2
how
fats
The
fat
which
has
a
high
molar
mass
is
converted
to
simpler
esters
molar
ester
link
is
broken
when
saponied
of
3
lower
the
are
how
in
transesterication,
the
mass.
alkyl
with
group
the
—COOR
of
alkyl
the
alcohol
group
group
of
in
the
swaps
the
ester.
Key points

Fats
and
oils
are
esters
of
glycerol
and
long-chain
carboxylic
acids
(fatty
acids).

Soaps
are
made
by
the
hydrolysis
of fats
or
oils
by
boiling
with
sodium
hydroxide.

Biodiesel

Transesterication
low
is
made
relative
by
the
process
involves
molecular
the
mass. A
of
transesterication.
reaction
different
of fats
ester
or
and
oils
with
glycerol
an
alcohol
of
are formed.
39
3.8
Testing for functional
Learning outcomes
Testing for the C=C double
Aqueous
On
completion
of
this
section,
be
able
bromine
Compounds
understand
tests for
water)
containing
is
used
double
to
test
bonds
for
are
the
also
C =C
bond
described
as
in
being
to:
unsaturated.

(bromine
bond
you
alkenes.
should
groups
that
there
are
So
the
test
is
also
a
test
for
unsaturated
compounds.
specic
On
addition
of
the
bromine
changes
bromine
water
to
unsaturated
compounds,
the
colour
of
particular functional
from
orange
to
colourless.
groups

describe
a
test for C =C
double
We
can
distinguish
Alkanes
do
not
alkenes
give
a
from
positive
alkanes
result
by
with
the
this
bromine
water
test.
test.
bonds

describe
and
tests for
the
— functional
—Cl,
—Br
groups
Halogenoalkanes

describe
tests
to
distinguish
–
Halogenoalkanes
between
alcohols,
alcohols
ketones
and
(in
a
solution
of
ethanol)
react
with
OH
ions
form
aldehydes,
carboxylic
and
halide
ions.
acids.
+
CH
CH
3
CH
2
Cl
+
–
Na
+
+
OH
→
CH
2
1-chloropropane
The
halide
ions
CH
3
CH
2
OH
+
Na
–
+
Cl
2
propan-1- ol
produced
in
this
reaction
can
be
identied
using
silver
nitrate.

Hydrolyse

Add
excess
the

Add
a

Observe
suspected
halogenoalkane
with
sodium
hydroxide.
–
few
nitric
drops
any

bromoalkanes

iodoalkanes
Add
a
an
(see
carbonyl
aldehyde
Section
Carboxylic
of
or
3.3
acids
delocalisation
in
1
can
Using

If
T
ollens’
an
light
n
is
darkens
which
precipitate
rapidly
darkens
which
slowly
does
not
darken.
aldehydes
present
give
a
the
a
ketones
suspected
deep
positive
carboxylate
reagent
is
to
and
orange
carbonyl
compound.
precipitate
is
formed
information).
reaction
from
(silver
present,
to
this
test
because
of
the
ion.
aldehydes
aldehydes
aldehyde
which
precipitate
yellow
reagent
between
distinguish
ions.
nitrate.
precipitate
cream
group
not
the
OH
ketones
more
do
white
a
a
silver
the
formed:
a
give
ketone
Dstngushng
We
give
Brady ’s
for
neutralise
aqueous
give
and
solution
to
precipitate
chloroalkanes
Test for
If
of

Aldehydes
acid
a
and
ketones
mir ror
silver
by
test)
ketones
three
–
‘mirror ’
see
is
tests.
Section
seen
on
3.3
the
side
of
the
test-tube.


40
Ketones
do
‘mirror ’
is
not
react
(the
mixture
remains
colourless).
No
silver
seen.
Methanoic
acid
it
gives
group
but
can
acidic
properties
be
a
positive
reaction
distinguished
typical
of
from
carboxylic
because
aldehydes
acids.
it
has
a
CHO
because
it
has
the
Chapter
2
Using

If
Fehling’s
an
aldehyde
oxide
3
is
Ketones

Methanoic
If
do
an
a
aldehyde
green
ketone

Primary
and
this
but
test
Carboxylic
1
of functional
groups
3.3
orange-red
precipitate
of
copper(
i)
a
mixture
positive
dichromate( vi)
remains
blue).
reaction.
or
potassium
manganate( vii)
–
see
is
present
the
present
acids
distinguish
no
secondary
they
do
and
by
the
orange
potassium
potassium
colour
give
acid
a
dichromate(
manganate(
change
alcohols
not
carboxylic
compounds)
the
purple
will
is
also
positive
vii)
observed
give
test
a
on
heating.
positive
with
vi)
decolourises.
result
Brady ’s
in
reagent.
halides
acids
from
following
alcohols
(and
many
other
reactions:
Acidity
A
2
Section
an
(the
gives
is
or
If
can
present
react
acid

organic
see
variety
3.3
turns
We
not
potassium
Section

is
–
A
formed.

Using
solution
3
solution
Reaction
Bubbles
of
a
with
of
carboxylic
sodium
carbon
acid
in
water
has
a
hydrogencarbonate
dioxide,
CO
,
are
pH
or
released
below
sodium
when
the
7.
carbonate
acid
is
added
to
2
a
carbonate.
The
presence
of
is
CO
detected
by
bubbling
the
gas
2
through
limewater
.
The
limewater
turns
milky
if
is
CO
present.
2
Acid
halides
water
.
given
The
off,
so
a
Alcohols
Alcohols
apart
off
Alcohols
be
fume
and
can
from
given
can
reaction
be
distinguished
is
can

carboxylic

alcohols
carboxylic
and
should
be
highly
used
acids
acidic
for
by
adding
choking
these
them
fumes
to
are
reactions.
esters
distinguished
with
be
from
vigorous
cupboard
carboxylic
(pops
very
a
acids
lighted
are
all
the
they
other
react
homologous
with
sodium.
series
above
Hydrogen
is
splint).
distinguished
acids
from
because
acidic
from
and
carboxylic
react
with
acids
because:
sodium
hydrogencarbonate
Key points
are
not
acidic
so
do
not
react
with
sodium
hydrogencarbonate.

Alcohols
which
contain
the
group
CH
CH(OH)
—
(many
secondary
be
3
alcohols

add
and
ethanol)
iodine
and
can
be
sodium
distinguished
by
the
iodoform
test:
identied
tests

hydroxide
Different functional
used
involving

a
precipitate
alcohol
or
of
yellow
crystals
shows
the
presence
of
a
them
with
are
distinguished
from
most
other
homologous
be
hydrolysing
series
by
sodium
the
ionic
hydroxide
product
and
with
their
aqueous
fruity
can
changes.
secondary
ethanol.
testing
Esters
by
can
qualitative
colour
Halogenoalkanes
distinguished
groups
silver
nitrate.
smell.

Alcohols,
can
be
oxidation
reaction

aldehydes
identied
by
reactions
with
Carboxylic
acidic
and
Brady’s
acids
can
distinguished from
their
and
ketones
various
by
reagent.
be
alcohols
by
nature.
41
4
Aromatic
4.
1
Some
compounds
reactions
Learning outcomes
completion
of
this
section,
be
able
describe
nitration

explain
the
of
the
hydrocarbons
ring
with
a
based
delocalised
on
benzene.
system
of
π
Benzene
electrons
has
a
above
six-membered
and
below
the
to:
plane

are
you
planar
should
benzene
Arenes
Arenes
On
of
bromination
and
of
the
structure
of
ring
(see
Unit
1
Study
Guide ,
Section
2.9).
This
stabilises
the
benzene.
benzene
steps
involved
mechanism for
the
bromination
benzene.
of
in
nitration
the
Did you know?
and
Some
arenes
many
centuries. This
compounds.
smells!
In
have
Many
rather
Electrophilic
and
delocalised
is
exposed
general
is
the
than
they
made
term
the
as
sweet-smelling
were
in
of
π
attack
named
the
laboratory
aromatic
now
oils from
aromatic
do
refers
to
plants for
(aroma-producing)
not
the
have
such
structure
nice
of
the
smell.
substitution
ring
to
extracted
why
arenes
chemistry
compounds
The
been
electrons
by
in
in
benzene
benzene
electrophilic
has
reagents.
a
high-electron
Figure
4.1.1
density
shows
the
mechanism.
+
El
H
C
H
C
H
C
H
H
H
C
H
C
C
H
C
El
C
C
C
C
El
+
+
C
C
+
C
H
C
H
H
H
H
H
H
C
C
C
H
H
H
+
Figure 4.1.1
General mechanism of nucleophilic substitution in benzene. El
represents an
electrophile.

The
so
electrophile
it
is

A
bond

This
T
o

The
forms
causes
carbon

attracted
regain
has
reacts
bromide
(or
a
the
is
replaced
a
with
charged
electron
system
to
positively
a
or
and
of
the
become
positively
the
charged,
benzene
benzene
unstable.
ring.
ring.
One
of
the
charged.
ion
is
substitution
hydrogen
partially
density
electrophile
hydrogen
reaction
iron
high
aromatic
Bromination of
Benzene
the
becomes
stability,
overall
reagent
positively
between
the
atoms
is
to
lost.
reaction
atom
in
the
because
benzene
the
electrophilic
ring.
benzene
bromine
filings
and
in
the
presence
bromine).
The
of
a
catalyst
overall
of
reaction
iron(
III)
is:
Br
+
Br
+
HBr
2
The
42
electrophilic
reagent
is
the
positively
polarised
bromine
molecule.
Chapter
The
highly
shown.
We
polar
say
iron( III)
that
bromide
iron( III)
the
causes
bromide
the
is
movement
a
halogen
of
electrons
4
Aromatic
compounds
as
carrier
.
Br
δ +
δ +
δ
δ
Br
The
mechanism
is
shown
in
Figure
a
4.1.2.
c
b
H
Br
Br
+
δ +
+
δ
+
+
FeBr
FeBr
3
Figure 4.1.2
HBr
3
FeBr
4
The bromination of benzene; a electrophilic attack; b intermediate formed;
+
ion and reformation of catalyst
c loss of H
Did you know?
In
the
reaction
between
bromine
and
benzene,
some
books
show
the
attacking
+
reagent
because
is,

as
it
Br
It
more
A

An

A
useful
to
bond
to
the
likely
electrophile
delocalised

is
conforms
however,
The
.
to
forms
the
general
bromine
with
pattern. The
a full
reaction
charge
shown
in
in
this
way
Figure
4.
1.2
occur.
(positively
electrons
unstable
show
in
between
the
the
positively
polarised
benzene
bromine
charged
bromine
molecule)
attacks
the
ring.
and
the
benzene
intermediate
is
ring.
formed.
Exam tips
–
hydrogen
ion
is
lost
and
combines
with
a
Br
from
the
to
FeBr
4
form
HBr
.
The
catalyst
FeBr
is
reformed.
3
Remember
end
in
alkenes
Nitration of
Benzene
reacts
sulphuric
although
they
do
not
arenes
behave
chemically. They
do
not
like
react
benzene
with
acids.
that
-ene,
a
The
mixture
overall
of
concentrated
reaction
nitric
and
with
bromine
they
are
water. This
is
because
concentrated
very
stable
because
of
the
is:
delocalised
ring
electrons.
NO
2
+
HNO
+
H
3
O
2
Key points
+
The
electrophilic
reagent
is
the
nitronium
ion,
NO
,
formed
by
the
2

nitrating
mixture
of
concentrated
nitric
and
sulphuric
The
of
+
HNO
+
2H
3
The
mechanism
is
SO
2
shown
→
NO
4
in
–
+
2HSO
2
Figure
H
O

c
of
reaction
arenes
involves
electrophilic
substitution.
3
4.1.3.
b
mechanism
+
+
4
In
of
a
main
acids:
the
electrophilic
arenes,
a
substitution
hydrogen
atom
in
NO
2
the
H
ring
is
replaced
by
Br,
NO
or
2
NO
2
+
another
suitable
group.
+
+
+
NO
H
2

When
benzene
is
nitrated,
+
the
nitronium
ion,
NO
is
the
2
Figure 4.1.3
The nitration of benzene; a electrophilic attack; b intermediate formed;
electrophilic
+
c loss of H
reagent.
ion

When
benzene
is
brominated,
is
required.
a
+

The
electrophile
(the
nitronium
ion,
NO
)
attacks
the
delocalised
2
halogen
electrons
in
the
benzene
ring.


A
bond
forms
between
carrier
the
nitro
group,
,
NO
and
the
benzene
The
electrophilic
reagent
in
the
ring.
2
bromination

An

A
unstable
positively
charged
intermediate
is
polarised
ion
is
lost.
This
reforms
the
benzene
is
the
formed.
+
hydrogen
of
sulphuric
acid
(H
bromine
molecule.
–
+
HSO
).
4
43
4.2
Methylbenzene
Learning outcomes
Substituted
Figure
On
completion
should
be
able
of
this
and
section,
4.2.1
nitrobenzene
arenes
shows
how
we
name
some
substituted
arenes.
you
a
to:
b
c
CH
d
CH
3
CH
3
NO
3
2
1

describe
the
bromination
NO
and
2
6
nitration
of
methylbenzene
2
and
3
5
NO
2
nitrobenzene
4
NO
2

explain
the
steps
mechanism
of
bromination
and

involved
nitration
of
in
the
and
methylbenzene
Figure 4.2.1
c
Some substituted arenes; a methylbenzene, b methyl-2-nitrobenzene,
methyl-4-nitrobenzene and d
1,3-dinitrobenzene
nitrobenzene
describe
the
reaction
of
The
nitrobenzene
concentrated
with
nitration of
methylbenzene
Sn/
Methylbenzene
HCl.

it

a
is
mixture
When
and
slightly
reacts
more
of
isomers
acids,
the
reactive
methylbenzene
sulphuric
with
is
the
is
nitrated
isomers
59%
methyl-3-nitrobenzene
4%
methyl-4-nitrobenzene
37%
the
it
CH
is
mainly
group
in
the
than
electrophiles
as
benzene
but:
benzene
obtained.
methyl-2-nitrobenzene
Because
same
2-
and
with
a
mixture
produced
4-
methylbenzene
isomers
is
2-,
of
concentrated
nitric
are:
that
are
produced,
we
say
that
4-directing.
3
This
is
ring.
(+
because
the
CH
group
tends
to
release
electrons
to
the
benzene
3
the
effect
–
intermediate
Figure
+
I
see
Section
formed
and
5.1.)
This
therefore
reduces
the
stabilises
positive
the
charge
intermediate
on
(see
4.2.2).
CH
3
The
have
Figure 4.2.2
possible
the
intermediates
positive
charge
on
formed
the
C
by
reaction
atom
next
at
to
the
the
2-
and
methyl
4-positions
group.
The
A methyl group tends to
possible
intermediates
formed
at
the
3-position
have
the
positive
charge
donate electrons to the benzene ring. The
on
other
carbon
atoms.
arrow shows the direction of movement of
the electrons.
Bromination
In
the
presence
reagent.
the
Exam tips
the
nitronium
ion
2-,
of
a
bromine
benzene
again,
When
A
and
ring.
A
nitration of
halogen
atom
is
carrier
,
methylbenzene
bromine
substituted
mixture
of
in
isomers
is
reacts
either
obtained.
4-directing.
is formed
CH
3
by
the
reaction
of
nitric
acid
with
Br
sulphuric
acid,
the
nitric
acid
behaves
CH
3
as
a
Brønsted–Lowry
base.
+
Br
2
+
FeBr
CH
3
3
Br
44
as
the
an
2-
electrophilic
or
The
4-positions
methyl
group
of
is
Chapter
The
nitration
Nitrobenzene

it
is

the
reacts
slightly
rather
than
less
it
is
is
bromination of
with
the
reactive
reaction
3-isomer
Because
and
at
the
than
room
mainly
mainly
same
(it
Aromatic
compounds
nitrobenzene
electrophiles
benzene
4
as
benzene
requires
but:
heating
to
50 °C
temperature)
obtained.
3-isomer
that
is
produced,
we
say
that
the
NO
2
group
This
in
is
nitrobenzene
because
the
is
3-directing.
NO
group
is
an
electron-attracting
group.
It
tends
to
2
withdraw
This
at
the
most
electrons
increases
2-
and
the
from
the
positive
4-positions.
benzene
charge
So
the
on
ring.
the
(–
I
effect
–
see
intermediate
intermediate
formed
Section
formed,
at
the
5.1.)
especially
3-position
is
stable.
a
b
NO
NO
2
2
NO
2
+
+
+
+
NO
+
H
2
NO
2
Figure 4.2.3
a A nitro group tends to withdraw electrons to the benzene ring. The arrow
shows the direction of movement of the electrons. b The equation for the overall reaction
+
ion with nitrobenzene.
of the NO
2
Reaction of
Aromatic
nitro
concentrated
product
reaction
is
a
nitrobenzene
compounds
hydrochloric
complex
with
phenylamine
alkali.
is
salt
are
acid.
of
With
the
with tin
reduced
by
Aromatic
amine.
reacting
amines
The
nitrobenzene,
and
an
HCl
with
are
amine
is
aromatic
tin
and
formed.
formed
amine
The
from
actual
this
by
called
formed.
NO
NH
2
2
+
6[H]
+
2H
O
2
Figure 4.2.4
A simplified equation for the reduction of nitrobenzene by tin and
concentrated hydrochloric acid. [H] represents the reducing power of hydrogen.
Exam tips
You
do
not
have
1
equations for
2
details
of
the
to
remember:
the
reaction
different
nitrobenzene
and
of
nitrobenzene
intermediates for
with
the
tin
and
nitration
hydrochloric
and
acid
bromination
of
methylnitrobenzene.
Key points

When
methylbenzene
formed

The
methyl
release

are
mainly
group
electrons
Nitrobenzene
concentrated
is
the
in
to
reacts
2-
with
and
electrophilic
4-isomers
methylbenzene
the
benzene
reduced
to
hydrochloric
ring
is
of
2-,
to
reagents,
4-directing
stabilise
phenylamine
the
products
methylnitrobenzene.
by
the
reaction
because
it
tends
to
intermediate.
with
tin
and
acid.
45
4.3
Phenol
and
Learning outcomes
dyes
Introduction
Phenol,
On
completion
of
this
section,

be
able
describe
with
aqueous
in
OH,
has
an
—OH
group
attached
directly
to
the
benzene
5
place
of
a
hydrogen
atom.
Phenol
is
only
sparingly
soluble
in
to:
the
acid
H
6
ring
should
C
you
reactions
halide
(acyl
bromine
of
phenols
halides),
and
sodium
water
because
water
molecules.
as
the
—OH
alcohols
are
the
large
The
group
not
group
—OH
in
(see
aryl
group
alcohols.
Section
minimises
does
For
not
hydrogen
always
example,
bonding
react
phenol
is
in
the
acidic,
with
same
way
whereas
5.2).
hydroxide

describe
the formation
of
azo
Reactions of the
compounds
and
the
reaction

state
Reaction
some
uses
of
—OH
group
in
phenols
coupling
with
alkalis
and
reaction
with
sodium
azo
Alcohols
do
not
react
with
sodium
hydroxide.
However
,
because
of
to
a
its
compounds.
acidic
character
,
(called
For
a
phenol
phenoxide)
example,
with
does
and
react.
It
reacts
with
alkalis
form
salt
water
.
sodium
hydroxide,
sodium
phenoxide
is
formed:
Exam tips
+
OH
+
NaOH
O
Na
+
H
O
2
Remember
that
when
you
write
phenol
the
ring
structure
compounds
you
may
with
see
the
of
substituent
structure
groups,
The
sodium
different
ways.
phenoxide
For
phenoxide
is
soluble
in
water
because
example,
reacts
with
sodium
2C
of
writing
phenol
is
ionic.
to
form
sodium
phenoxide
and
hydrogen.
two
–
ways
it
written
Phenol
in
sodium
aromatic
H
6
are:
OH
+
2Na
→
2C
5
H
6
O
+
Na
+
H
5
2
OH
Reaction
or
OH
with
Acyl
halides
PCl
(see
acyl
(acid
Section
halides
halides)
3.5).
are
Acyl
(acid
formed
halides
halides)
when
react
carboxylic
with
phenols
acids
to
react
form
with
esters.
The
5
Remember
that
these
are
the
same
OH
bond
also
structure.
in
react
the
with
phenol
acyl
in
+
OH →
C
3
chloride
Substitution

A
reacts
lone
pair
This

So

The
at

So
OH
more
the
intermediates
the
2-,
the
4-
and
reaction
ring
are
on
the
electron
charge
are
HCl
COOC
3
in the
on
with
the
more
atom
ring
Alcohols
+
in
HCl
5
the
hydrogen
than
compared
benzene.
with
Section
aromatic
is
chloride
ring
overlaps
(see
intermediates
stable
H
electrophiles
oxygen
density
released.
ethanoate
aromatic
aromatic
the
are
6
phenyl
rapidly
in
of
manner
.
CH
5
electrons
positive
Fumes
similar
phenol
electrons
increases
the
the
of
a
reactions
much
delocalised

H
6
ethanoyl
Phenol
broken.
halides
COCl
CH
is
the
5.2).
ring.
reduced.
with
benzene
(especially
6-positions).
occurs
under
milder
conditions
and
more
positions
substituted.
OH
Br
+
Br
3Br
+
3HBr
The
reaction of
phenol
with
bromine
2
Bromine
Br
46
water
reacts
2,4,6-tribromophenol
rapidly
is
with
formed.
phenol.
No
A
halogen
white
precipitate
carrier
is
needed.
of
in
Chapter
Diazotisation
and
coupling
4
Aromatic
compounds
reactions
Exam tips
Diazotisation
The
Phenylamine,
C
H
6
NH
5
,
an
aromatic
amine,
reacts
with
nitrous
acid
reaction
other
the
presence
of
of
phenol
with
in
2
hydrochloric
acid
to
form
a
diazonium
salt
electrophiles
also
occurs
(general
under
milder
conditions
and
with
+
formula
TNX
RN
).
This
process
is
called
diazotisation
more
positions
substituted.
in
For
the
ring
example,
being
nitration
+
NH
+
HNO
2
+
HCl
N

NCl
+
2H
2
O
2
only
phenylamine
nitrous
benzene
acid
Nitrous
acid
is
unstable
and
(no
diazonium
is
made
by
dilute
sulphuric
acid
nitric
is
adding
NaNO
and
HCl
to
acid
needed)
2,4,6-trinitrophenol
chloride
so
requires
and
is formed.
the
2
phenylamine.
the
The
diazonium
Coupling
reaction
salt
decomposing
an
orange
coupling
below
to
has
to
be
kept
below
10 °C
to
prevent
nitrogen.
reaction
Benzenediazonium
form
mixture
dye
reaction .
10 °C
to
chloride
reacts
with
an
alkaline
(4-hydroxyphenylazobenzene).
The
prevent
temperature
of
decomposition
the
of
solution
This
solution
the
is
must
diazonium
of
phenol
called
be
to
a
kept
well
salt.
+
N
benzene

NCl
OH
diazonium
phenol
orange
dye
chloride
Figure 4.3.1
A coupling reaction is the reaction of a diazonium salt with a phenol under
alkaline conditions
The
positive
substitutes
charge
into
on
the
the
diazonium
4-position
of
the
ion
ring
acts
of
as
the
an
electrophile
and
phenol.
Exam tips
The
important

aromatic

HNO
is
points
amines
about
and
made from
the
diazotisation
phenols
NaNO
2
are
and
and
coupling
reactions
are
that:
involved
HCl
2
Key points

the
reaction

substitution
is
carried
of
the
out
diazo
below
10 °C
compound
is
at
the
4-position
in
the
phenol
ring

Phenols
groups

azo
compound
have
the
N=N
have

Azo dyes
dye
formed
—N=N—
aromatic
coloured
in
group
amines
dyes.
the
coupling
attached
and
The
to
colour
reaction
two
different
or
more
directly
—OH
to
the
link.
benzene
The
one
attached
is
an
aromatic
phenols,
depends
on
we
the
azo
rings.
can
dye.
By
make
amine
and
It
contains
using
a
phenolic
of
—OH
group
with
NaOH
with
acid
in
phenol
to form
halides
a
salt
to form
reacts
and
esters.
the
different
variety
The
ring.

brightly
The
the
electrophilic
ring
of
substitution
phenol
is
rapid
in
due
compound
to
activation
of
the
ring
by
the
used.
—OH

group.
Phenylamine
reacts
with
Did you know?
o
nitrous
acid
below
benzenediazonium
Diazonium
compounds
are
important
as
intermediates
in
organic
10
C
to form
chloride.
synthesis.
+
The
N
with
T
KI
NX
to
aromatic
group
produce
cyanides.
can
be
replaced
substituted
by
a
variety
of
iodo-compounds,
other
groups,
reaction
e.g.
with CN
reaction
to
produce

A
coupling
when
reaction
diazonium
phenols
to form
occurs
salts
azo
react
with
dyes.
47
Reision
Answers to
1
A
all
revision questions
compound
i
reacts
ii
turns
iii
does
has
readily
blue
can
the following
with
litmus
be found on the
accompanying CD.
properties:
bromine
paper
questions
6
What
is
the
correct
compounds
water
pink
order
of
increasing
acidity
of
the
below?
OH
OH
CH
OH
2
not
cause
aqueous
Which
of
efferescence
sodium
when
mixed
with
carbonate.
the following
compounds
most
accurately
CH
3
exhibits
all
of
the
aboe
properties?
X
A
C
H
6
B
C
C
C
D
C
H
6
NH
5
H
6
2
COOH
5
H
6
2
CONH
5
Which
2
of
these
statements
best
explains
the
Z
of
A
Z Y X
B
Z X Y
C
Y
D
X Y
Z X
Z
weak
7
acidity
A
compound
H
The C
6
O
H
A, C
3
phenol?
acidified
–
A
Y
OH
5
ion
is
a
weak
conjugate
O,
when
refluxed
with
8
potassium
dichromate(vI)
produced
a
base.
5
liquid
B,
with
a
sharp
smell,
which
efferesced
with
–
B
H
The C
6
O
ion
is
stabilised ia
delocalisation
of
5
sodium
charge
into
the
benzene
carbonate
containing
C
C
H
6
OH
is
a
stronger
acid
than
an
two
atoms,
when
compound
heated
C,
with
aqueous
concentrated
of
carbon
dioxide
(carbonic
acid).
H
6
OH
will
efferesce
with
potassium
sulphuric
acid
at
temperatures
of
°
about
C
carbon
5
solution
D
solution. Another
ring.
160
C
produced
a
sweet-smelling
gas
D,
which
carbonate
5
decolourised
aqueous
bromine.
C
also
produced
solution.
yellow
crystals
hydroxide
3
Which
of
the following
reagents
best
propan-1-ol
and
Cr
B
NaOH(aq)/
/H
(aq)
conc.
H
a
SO
2
D
4
of
produced
Explain
C,
Na(s)
Which
the following
by
A
alkanes
B
alkynes
C
alkenes
concentrated
sweet-smelling
and
b
4
of
perfumery
7
2
C
the
classes
dehydration
of
of
compounds
is
c
acid
B
in
the
produced
compound.
E
is
used
in
the
the
arguments
used
D
and
the
also
Write
of
to
the
deduce
the
names
compounds
A,
B,
E.
equations for
B
the
and
the
sodium
type
of
reactions
of
C
and
B,
carbonate.
reaction
which
produces
D
and
E.
a
Explain
the
terms
as
‘primary’,
applied
to
‘secondary’
and
alcohols.
arenes
b
There
are four
H
formula C
4
Which
compound
is
most
likely
to
be formed
phenol
is
reacted
with
bromine
A
4-bromophenol
B
2,4,6-tribromophenol
C
3-bromophenol
D
2,3-dibromophenol
in
an
organic
structural
isomeric
alcohols
with
O.
10
when
i
Write
the
names
these
alcohols
and
structural formulae
of
solent?
terms
ii
c
in
a
and
classify
laboratory
between
these
of
these
them
according
to
aboe.
Describe
One
of
48
sodium
with
industry.
‘tertiary’
5
with
refluxed
sulphuric
structural formulae
Gie
and
alcohols?
8
D
warmed
when
propan-2-ol?
a
A
2
gently
+
2–
O
when
iodine. C
differentiates
presence
between
and
isomers
concentrated
of
when
sulphuric
different
compounds.
i
State
the
ii
Explain
type
the
tests
groups
of
distinguish
heated
acid
reaction
production
to
compounds.
of
with
produces
an
excess
three
inoled.
these
compounds.
Chapters
9
a
Explain
when
alkyl
b
and
Explain,
would
characteristic
hydroxyl
the
see
when
ethanoyl
ii
an
A
the
write
aid
ring
of
is
in
groups
and
aromatic
compounds
–
revision
questions
effect
bonded
to
an
respectiely.
an
phenol
is
Functional
equation,
added
what
you
to:
chloride
aqueous
the
sequence
difference
group, OH,
benzene
with
i
and
c
the
the
3–4
solution
of
bromine
structural formula for
of
two
reactions
is
the
shown
product.
below:
OH
NH
2
I
II
X
Y
NaOH
brightly
coloured
i
Write
the
ii
the
names
compounds
Write
the
and
X
structural formulae for
and
reagents
Y.
and
conditions for
reaction
I.
iii
10
Name
Compare
and
the
and
phenol,
equations
type
contrast
with
reactions
the
in
reactions
the following
wheneer
appropriate
of
possible
I
of
and
propan-1-ol
reagents,
and
II.
giing
describing
obserations:
i
water
ii
blue
iii
potassium
iv
phosphorus(v)
v
ethanoic
litmus
paper
hydroxide
chloride
acid.
49
5
Organic
5.
1
Carboxylic
acids
Learning outcomes
and
acids
K
bases
and
values of
acidity
some
carboxylic
acids
a
Carboxylic
On
completion
of
this
section,
acids
(dissociated)
should
be
able
are
weak
acids.
They
are
not
completely
ionised
you
in
solution.
The
position
of
equilibrium
is
well
over
to
the
to:
left.
For
example,
ethanoic
acid
COOH).
(CH
3

explain
the
difference
in
acidity
+
CH
of

alcohols
and
understand
carboxylic
why
substitution
increasing
of Cl
onto
the
COOH
+
H
3
acids
The
table
shows
O
Y
CH
2
some
K
and
pK
a
COO
+
H
3
values
O
3
for
different
carboxylic
acids.
a
the
–3
carbon
atom
—COOH
next
group
to
Carboxylic
the
results
acid
K
mol dm
pK
a
a
in
–5
ethanoic
stronger

acid, CH
understand
the
COOH
effect
of
×
10
the
4.77
–5
propanoic
CH
acid, CH
3
conjugative
1.7
3
acidity
(mesomeric)
COOH
1.3
×
10
1.3
×
10
4.89
2
effect
–3
and
inductive
effect
on
chloroethanoic
ClCOOH
acid, CH
2.89
2
determining
the
acidity
of
various
–2
substituted
in
carboxylic
acids
dichloroethanoic
and
COOH
acid, CHCl
5.0
×
10
2.3
×
10
1.30
2
alcohols.
–1
trichloroethanoic
COOH
acid, CCl
0.64
3
The
values
of
K
and
pK
a
equilibrium
give
us
information
about
the
position
of
a
(see
Unit
1
Study
Guide ,
Section
9.3).
The
higher
the
value
Did you know?
of
and
K
the
lower
the
value
of
pK
a
Trichloroethanoic
acid
is
used
to

remove
skin
imperfections
wrinkles. The
cosmetic
and
be
as
carried
a
chemical
out
supervision
under
because
further
the
position
of
equilibrium
is
to
the
right
(in
favour
of
treatment,
peel,
We
medical
this
acid
treatment
the
greater
the
acidity
of
the
carboxylic
acid.
must
can
explain
these
differences
by
referring
to
two
effects:
is

corrosive. After
the
products)

known
:
a
The
conjugative
effect
(also
known
as
the
mesomeric
or
resonance
the
effect).
patient
appears
to
have
sunburn!

The
The
The
inductive
conjugative
conjugative
when
the
single
makes
over
the
ordinary
e.g.
single
structure
at
occurs
rst
benzene.
three
bond
effect
effect
structure
bonds
system
the
effect.
or
more
lengths
bonds
more
The
stable.
molecules
appears
π
atom
and
and
in
sight
orbitals
centres
bond
(see
double
bonds
in
carbonate

the
carbon–oxygen
bonds
in
carboxylate
an
example:
O
R
C
O
50
bonds,
Section
form
1.1).
The
showing
a
usually
double
and
delocalised
The
effect
between
effect
this
also
effect
makes
are:
ions
acids.
as
and
intermediate
compounds
carbon–oxygen
acids
multiple
alternating
bonds.
the
carboxylic
of
overlap

T
aking
with
be
strengths
ordinary
Other
to
H
ions
derived
from
carboxylic
Chapter

Oxygen
atoms
hydrogen
are
more
electronegative
than
carbon
atoms
5
Organic
The
bonding
shown
and
bases
or
atoms.
a

acids
by
pairs
the
of
electrons
arrows
in
the
tend
to
diagram
move
on
towards
page
the
atoms
O
O
as
R
50.
C
R
C
O

The
O—H
bond

The
carboxylate
is
weakened
so
that
it
is
possible
for
a
proton
to
be
O
lost.
O
b
ion
formed
exists
as
a
resonance
hybrid
of
two
R
extreme
forms.
The
actual
form
is
somewhere
in
between
these
C
two
O
extremes
(Figure
5.1.1).
+

The
carboxylate
combine
with
ion
it
is
is
relatively
stable,
so
the
ability
of
the
ion
H
to
Figure 5.1.1
Conjugative effect in the
carboxylate ion; a
reduced.
The extreme resonance
forms; b The resonance hybrid
The
inductive
Bonds
between
effect
unlike
atoms
are
polarised
due
to
the
difference
H
in
weakest
electronegativity
between
the
atoms
(see
Unit
1
Study
Guide ,
Section
C
acid
2.5).
The
more
polarisation
electronegative
attracting
such
as
or
a
is
represented
atom.
withdrawing
carbon
atom.
Groups
effect
This
is
on
by
of
arrow
atoms
the
called
an
can
electrons
the
pointing
also
exert
around
inductive
towards
a
an
H
2
the
H
electron-
particular
atom
Cl
effect
C
H
2

Atoms
or
groups
more
electronegative
than
carbon
withdraw
electrons
H
from
around
the
carbon
atom.
This
is
called
the
negative
inductive
Cl
effect
(–
I
effect).
For
example
chlorine
bonded
to
carbon.
C
H
2
Cl
C
Cl
Cl

Atoms
or
electrons
effect
(
groups
to
+I
the
less
electronegative
carbon
effect).
For
atom.
This
example
than
is
alkyl
carbon
called
groups
the
tend
to
positive
bonded
to
donate
inductive
C
strongest
carbon.
H
2
acid
Cl
H
CH
CH
3
3
Figure 5.1.2
CH
C
H
CH
3
C
CH
3
As the number of electron-
withdrawing groups on the COOH carbon
C
3
atom increases, the strength of the acid
H
H
CH
increases
3
increasing
+I
effect
Key points
Comparing
acidity:
chloroethanoic
acids
–

The
table
opposite
shows
the
pK
values
of
chloroethanoic
acid
and
—COO
acids
a
dichloroethanoic
The
trichloroethanoic
acid.
We
can
ion
explain
is
stabilised
in
acidity
of
the
chloroethanoic
acids
by
the
inductive
The
more
Cl
atoms
that
are
substituted
in
the
group
CH
in
The
acid
strength
the
greater
is
the
electron-withdrawing
(–
I)
increases
the COOH
effect
on
the
the
C
The
—COOH
greater
the
carbon
and
–I
effect,
the
more
the
electrons
are
withdrawn
the
Carboxylic
the
more
the
electrons
in
the
O—H
bond
are
oxygen
than
The
more
the
to
atoms
bonded
to
it.
acids
are
alcohols
stronger
because
of
drawn
effect
of
the
conjugative
and
atom.
inductive

next
electron-
from
the
towards
has
group.
acids
the
carboxylic
atom


of
the C
group
withdrawing
of
if
ethanoic
3
acid,
effect.
effects.
acids

the
(mesomeric)
and

conjugative
carboxylic
by
the
conjugative
difference
in
acid,
electrons
are
drawn
towards
the
O
atom
in
the
effects
on
the
—COOH
OH
group.
+
bond,
be
the
weaker
the
bond
and
the
more
likely
it
is
that
a
H
ion
will

formed.
The
greater
atoms

The
greater
the
–I
effect,
the
greater
is
the
delocalisation
of
So
the
on
of Cl
the
carbon
next
to
the
—COOH
group,
charge.
the

number
the
atom
negative
the
substituted
greater
is
the
conjugative
effect
and
the
more
likely
it
is
that
greater
the
acidity
of
the
a
carboxylic
acid.
+
H
ion
will
be
formed.
51
5.2
Comparing
Learning outcomes
acidities
Introduction
Ethanol
On
completion
of
this
section,
form
should
be
able
explain
the
between

difference
in
acidity
phenols
mass
and
the
difference
alcohols
terms
of
the
are
soluble
bonding
in
with
water
.
water
.
This
is
Phenol
because
is
only
they
can
sparingly
orbitals
and
water
large
and
aryl
however
,
ethanol.
is
a
ring
solid
although
Why
is
at
reduce
room
its
less
temperature.
hydrogen
acidic
than
Its
bonding
ethanoic
higher
capacity
acid
is
molar
with
more
water
.
acidic
this?
in
and
overlap
The
stability
acidity of
compounds
with
—OH
groups
of
The
atomic
in
and
Phenol,
than
between
phenols
in
acids
understand
acidity
acid
hydrogen
to:
alcohols,
carboxylic
ethanoic
extensive
soluble

and
you
table
shows
the
pK
values
for
some
compounds
containing
the
a
of
—OH
group.
The
lower
the
value
of
,
pK
the
more
acidic
the
compound.
a
the
phenoxide
and
alkoxide
ions.
Compound
Formula
pK
a
ethanoic
acid
CH
COOH
4.8
3
phenol
H
C
6
ethanol
Phenol
H
C
is
a
phenoxide
very
weak
acid.
OH
10.0
5
OH
16.0
2
5
It
ionises
slightly
in
water
to
–
H
C
6
OH(s)
+
aq
Y
than

is
An
much
or
water
Phenol
is
whereas

can
acid
by
O
+
(aq)
phenoxide
weaker
acid
than
+
H
(aq)
5
ethanoic
ion
acid
but
it
is
more
acidic
solution
appear
too
weak
ethanol
of
phenol
neutral
an
acid
nor
with
acid
to
will
water
has
a
pH
narrow
liberate
liberate
will
just
range
carbon
carbon
neutralise
below
7
whereas
universal
dioxide
alcohol
indicator
from
paper
.
carbonates
dioxide.
sodium
hydroxide
but
does.
Ethoxide,
We
H
6
ethanoic
Neither
phenol
the
ethanol.
aqueous
and

a
water
C
5
phenol
Phenol
form
ion.
phenoxide
explain
the
comparing
and
differences
the
in
structure
ethanoate
acidity
of
the
of
ions
ethanol,
phenoxide,
phenol
and
ethoxide
and
ethanoic
ethanoate
ions.
Ethanol

The
charge
oxygen
and
a
CH
CH
3
the
on
atom
any
ethanoate
because
of
the
electronegativity
of
ions
formed
positive
the
O
is
concentrated
inductive
effect
of
on
the
the
ethyl
group
atom.
O
2

This
increases
the
negative
charge
on
the
oxygen
atom.
So
any
+
ethoxide
+
b
CH
3
CH
formed
is
more
likely
to
accept
a
ion.
H
O
2

Figure 5.2.1
ion
There
is
no
conjugative
effect
to
stabilise
the
ethanoate
ion
since
a The ethoxide ion has
ethanol
does
not
have
a
C =O
group.
negative charge concentrated on the
oxygen; b A hydrogen ion is readily
attracted to the highly charged negative ion
52

The
position
exists
as
of
equilibrium
undissociated
is
so
molecules
far
over
with
to
the
hardly
left
any
that
the
ethanoate
ethanol
ions.
Chapter
5
Organic
acids
and
bases
Phenol

In
the
on
phenoxide
the
oxygen
phenol

An

Figure
The
delocalised
can
The
extra
The
charge
the
the
lone
with
system
(resonance)
move
over
a
delocalisation
is
spread
the
pairs
of
electrons
delocalised
in
a
p- orbital
electrons
in
the
is
formed
which
includes
the
oxygen
effect
larger
reduces
over
the
is
increased
because
the
delocalised
area.
the
electron
whole
ion
density
rather
than
on
the
being
oxygen.
conned
to
oxygen.

The
increased

The
conjugative

of
5.2.2).
conjugative
electrons

one
overlaps
ring.
extended
(see
ion,
atom
conjugative
movement
of
ring
rather
than
The
position
effect
the
of
is
effect
greater
electrons
towards
in
the
equilibrium
stabilises
than
the
the
C—O
the
phenoxide
inductive
bond
is
ion.
effect,
towards
so
the
the
phenol
oxygen.
is
further
to
the
right
compared
with
ethanol.
+

ions
H
are
phenoxide
the
not
ion
ethoxide
as
is
strongly
less
attracted
likely
to
form
to
the
phenoxide
undissociated
ion.
So
molecules
the
than
is
ion.
Did you know?
a
b
c
O
Phenol
is
used
to
make
antiseptics
O
O
such
was
in
as
‘Dettol’
the rst
surgery.
operating
Figure 5.2.2
The extended delocalised ring system in phenol; a
‘TCP’.
antiseptic
In
the
19th
theatres
to
Phenol
be
used
century
were
sprayed
with
The isolated p-orbitals;
it.
b The delocalised ring system; c
and
Death
rates from
infection
were
The movement of electrons in the C—O bond is towards
greatly
reduced
by
its
use. We
do
the ring
not
use
now
Ethanoic
phenol
because
itself for
it
can
this
cause
purpose
burns
and
acid
is
toxic.
–

Some

This
of
the
p-electrons
delocalisation
charge
is
spread
in
the
reduces
over
the
COO
the
whole
group
electron
ion
are
delocalised.
density
rather
than
on
the
being
oxygen
conned
(the
to
the
Key points
oxygen
of
the
O—H
group).

The
conjugative
effect
stabilises
the
ethanoate

The
conjugative
effect
is
than
ion.

the
ion
is
greater
in
phenol,
so
the
stabilisation
The
is
weakly
than
acidic
ethanol
or
but
more
water.
greater
.


Phenol
acidic
of
position
of
equilibrium
is
further
to
the
right
compared
with
Phenol
is
less
carboxylic
acidic
than
acids.
phenol.

The
acidity
in
phenols
is
due
+

H
ions
are
ethanoate
the
not
ion
as
is
phenoxide
strongly
less
likely
attracted
to
form
to
the
ethanoate
undissociated
ion.
So
molecules
the
than
to
is
on
the
delocalisation
the
phenoxide
of
ion
charge
with
the
ion.
delocalised
phenol
a
electrons
in
the
ring.
b
CH

C
The
alkoxide
ion
does
not
have
3
CH
C
3
O
delocalised
charge
associated
–
with
Figure 5.2.3
The delocalised electrons in the COO
ion; a The isolated p-orbitals;
the O
atom.
readily
accepts
form
molecule.
a
a
So
the O
hydrogen
ion
to
b The delocalised electrons in the carboxylate ion
53
5.3
Amines,
Learning outcomes
On
completion
should
be
able
of
this
amides
state
the
acyl
halides
Introduction
section,
Amines
are
thought
of
compounds
with
the
—NH
functional
group.
Amines
can
be
2
you
as
ammonia
molecules
in
which
one
or
more
of
the
hydrogen
to:
atoms

and
difference
in
basic
has
been
substituted
functional
—CONH
by
group.
an
The
alkyl
group.
structures
Amides
of
some
have
of
the
these
compounds
2
character
aromatic
of
aliphatic
amines
and
amines,
are
shown
below.
amides
H
CH
N
CH
3

explain
the
difference
in
CH
CH
3
character
of
aliphatic
CH
3
N
CH
3
3
basic
N
2
H
amines,
CH
3
H
aromatic
amines
and
amides
in
ethylamine
terms
of
the
inductive
(a
conjugative
dimethylamine
trimethylamine
and
primary
amine)
(a
secondary
amine)
(a
tertiary
amine)
effects.
NH
=
O
2
CH
C
H
N
3
H
phenylamine
(an
Basic
aromatic
character of
Amines
are
example,
weak
ethanamide
amine)
bases.
methylamine
(an
amide)
amines
The
(CH
position
NH
3
of
equilibrium
lies
NH
3
Amines
react
with
+
H
2
acids
to
O
Y
CH
2
form
NH
3
NH
3
The
table
shows
the
pK
left.
For
–
+
OH
3
salts.
+
CH
the
2
+
CH
to
).
+
HCl
→
CH
2
NH
3
values
for
–
Cl
3
ammonia
and
some
amines.
The
b
lower
the
value
of
,
pK
the
more
basic
is
the
compound.
b
Compound
Formula
pK
b
Ammonia
NH
4.7
3
Methylamine
NH
CH
3
Dimethylamine
)
(CH
3
Phenylamine
C
H
6
3.4
2
NH
3.3
2
NH
5
9.4
2
Exam tips
The
Remember
that
the
values
of
strength
of
a
base
depends
on
the
availability
b
us
position
the
information
of
value
about
pK
lower
the further
favour
of
Methylamine

the
equilibrium
the
nitrogen
atom
to
bond
to
a
lone
pairs
of
ion.
H
is
a
stronger
base
than
ammonia
because:
:
b

on
the
equilibrium. The
of
the
+
electrons
gives
of
pK
is
position
to
the
to
of
right
the
(in

so
methyl
the
the
lone
density
products)
group
nitrogen
is
electron-donating
(+ I
effect).
It
releases
electrons
atom.
pair
on
compared
the
with
N
atom
the
of
the
electron
amine
density
has
of
a
the
higher
N
electron
atom
in
ammonia.

the
greater
the
basicity
of
the

the
lone
pair
on
the
N
atom
of
methylamine
is
better
at
accepting
amine.
+
H
54
ion
from
water
(compared
with
the
N
atom
of
ammonia).
a
Chapter
Secondary
amines
have
two
alkyl
groups
so
are
stronger
bases
than
5
Organic
acids
the
and
bases
H
a
:
corresponding
primary
amines.
T
ertiary
amines,
however
,
are
weaker
CH
N
3
bases
than
ammonia.
H

is
phenylamine
Phenylamine
is
a
amines.
is
because
very
a very
weak
base
weak
compared
with
CH
b
base?
3
:
Why
ammonia
and
alkyl
CH
3
This
of
the
conjugative
(resonance
effect).
Figure 5.3.1

In
the
phenylamine
molecule
the
lone
pair
of
electrons
in
a
a Methylamine is a stronger
p- orbital
base than ammonia because of the + I effect
on
the
nitrogen
atom
overlaps
with
the
delocalised
electrons
in
the
of the methyl group. b Dimethylamine is a
stronger base than methylamine because it
ring.
has two + I effects.

An
extended
atom

The
(see
Figure
conjugative
electrons

delocalised
The
can
extra
system
is
formed
which
includes
the
nitrogen
5.3.2).
(resonance)
move
over
a
delocalisation
effect
larger
is
increased
because
the
delocalised
area.
reduces
the
electron
density
on
the
nitrogen
atom.

The
increased

The
conjugative
movement
rather

The
of
than
conjugative
effect
the
of
the
stabilises
greater
electrons
towards
position
is
effect
in
than
the
nitrogen
equilibrium
is
the
C—N
the
phenylamine
inductive
bond
is
effect,
towards
molecule.
so
the
the
ring
atom.
much
further
to
the
left
compared
with
ammonia.
Exam tips
+

So
ions
H
atom
from
compared
water
with
are
the
not
as
stronger
strongly
attracted
attraction
to
the
to
N
the
nitrogen
atom
in
Phenylamine
ammonia.
making
:
a
b
azo
is
the
diazonium
dyes.
Make
starting
point for
compounds
sure
that
you
and
know
c
N
these
reactions
Section
by
referring
back
to
4.3.
N:
N:
Figure 5.3.2
The extended delocalised ring system in phenylamine; a The isolated
p-orbitals; b The delocalised ring sytem; c The movement of electrons in the C—N bond is
towards the ring.
Key points
Amides

Amides
are
much
weaker
bases
than
amines.
For
example
the
p K
ethanamide
is
14.1.
Amides
are
neutral
to
litmus
and
do
not
Amines
react
acid
to
form
salts.
This
is
the
a
p- orbital
on
the
nitrogen
atom
lone
atom
pair
carbon
interacts
with
a
p- orbital
on
there
is
which
This
reduces
not
the
electrons
to
accept
on
a
the
proton.
Amines
are
stronger
because
bases
the
than
electron-
atom
considerable
does
because
the
releasing

of
tends
ammonia
adjacent
bases
because:


as
with
N
hydrochloric
behave
of
b
delocalisation
occur
ability
in
of
ammonia
the
lone
between
or
pair
alkyl
on
the
O,
C
and
N
atoms
the
amines.
the
nitrogen
nitrogen
atom
to
accept
a

alkyl
electron
group
density
increases
on
the
atom.
Phenylamine
is
a
weaker
base
+
H
ion
from
water
.
than
lone
O
a
O
b
ammonia
pair
C
R
C
because
electrons
the
on
the
O
nitrogen
R
of
R
atom
in
phenylamine
is
C
delocalised
with
the
delocalised
+
N
H
electrons
in
the
aromatic
ring.
H
H
H

Figure 5.3.3
a The conjugative (resonance) effect provided by the carbonyl group in
Amides
do
not
are
neutral
react
with
to
litmus
and
acids.
amides stabilises the structure; b The resonance hybrids of an amide
55
5.4
Amino
acids
Learning outcomes
The
structure of
Amino
On
completion
of
this
section,
be
able
explain
the
amino
acid–base
and
understand
state
that
naturally
which
group
will
(—NH
undergo
)
and
most
the
of
carboxylic
the
reactions
acid
of
carboxylic
acids.
amino
acids
most
often
found
in
living
organisms
have
the
—NH
2
acids
the
term
to
amino
acids
occurring
make
up
the
carbon
atom
next
to
the
—COOH
group
( α-amino
acids
or
‘zwitterions’
2-amino

acids
properties
bonded

amino
Amino
to:
The
of
the
2
(—COOH).
amines

contain
acids
you
group
should
acids
amino
are
compounds
proteins.
shows
acids).
the
greatly;
it
general
can
non-polar
types
of
Most
be
(see
structure
acidic,
Figure
amino
amino
acids
of
basic
5.4.2).
an
or
exist
as
amino
neutral.
Y
ou
do
not
optical
acid.
The
Neutral
have
isomers.
to
R
R
Figure
group
groups
know
details
H
NH
vary
be
of
polar
or
these
acid.
H
a
can
can
5.4.1
H
b
C
C
COOH
C
2
COOH
NH
2
2
CH
R
CH
3
3
or
RCH(NH
)COOH
2
Figure 5.4.1
a General structure of an amino acid; b The two optical isomers of the amino
acid, alanine
a
NH
CH
b
COOH
NH
2
CH
CH
COOH
(CH
2
c
NH
CH
)
2
d
COOH
NH
2
NH
4
CH
2
COOH
2
CH
CH
3
Figure 5.4.2
COOH
2
Amino acids with a
non-polar side chain and d
OH
2
an acidic side chain; b
a basic side chain; c a neutral
a neutral polar side chain
Zwitterions
The
basic
—NH
and
acidic
—COOH
group
in
amino
acids
can
react
2
with
each
negative
an
is
and
In
The
word
zwitterion
parts
hence
the
An
formed.
electrically
different
Did you know?
other
.
the
of
carrying
This
neutral
the
of
type
species.
a
of
species
‘molecule’
formation
comes from
ion
is
two
ion
with
The
charges,
is
a
called
a
positive
positive
one
negative
negative
a
H
A
the
other
zwitterion
ion
in
charges
two
cancel
neutral.
zwitterion
in
amino
acids
the
+
lost
and
zwitterion.
and
and
positive
—COOH
group
has
+
ion
and
the
—NH
group
has
gained
a
H
ion.
2
the German
means
word
hybrid.
zwitterions
‘zwitter’
Substances
are
which
H
containing
sometimes
+
called
H
N
C
COO
3
ampholytes
or
electrolytes. A
from
plants
amphoteric
number
such
as
of
CH
chemicals
3
alkaloids form
Figure 5.4.3
The zwitterion of the amino acid alanine
zwitterions.
Amino
forces
acids
of
‘zwitterions’.
56
are
crystalline
attraction
between
solids
the
because
positive
of
and
the
relatively
negative
parts
strong
of
ionic
adjoining
is
Chapter
Acid–base
In
solution,
properties of
amino

The
—COOH

The
—NH
acids
group
group
amino
acids
show
both
acidic
reacts
with
alkalis
reacts
with
acids
to
5
and
to
basic
form
form
properties.
a
metal
salt.
salts.
2
Amino
acid
acids
and
Section
The
is
In

as
buffer
base
solutions
within
the
because
same
they
molecule
have
(see
a
Unit
supply
1
of
Study
weak
Guide ,
9.7).
charge
placed.
side
act
weak
on
The
the
amino
following
acid
depends
argument
on
the
applies
for
type
of
amino
solution
acids
in
with
a
which
it
neutral
chain.
solution
Both
the
in
water
—NH
(neutral
and
solution)
—COOH
groups
are
ionised:
2
–
+NH
—CH(R)—COO
3
+

The
positive
charge
on
the
NH
ion
balances
the
negative
charge
on
3
–
the

In

ion.
COO
The
solution
acidic
The
is
electrically
neutral.
solution
acid
provides
hydrogen
ions,
e.g.
from
hydrochloric
acid.
+

The
lone
pair
on
the
N
atom
of
the
—NH
group
is
already
3
+
protonated
positively
in
the
zwitterion.
The
addition
of
keeps
H
this
group
charged.
–

The
—COO

The
amino
ion
acid
is
is
a
proton
positively
acceptor
.
charged.
H
H
+
+
+
H
N
C
COO
+
H
H
3
N
C
COOH
3
R
R
Did you know?
In
alkaline
solution
Amino
–

The
alkali
provides
OH
ions,
e.g.
from
sodium
acids
may
have
acidic
or
hydroxide.
basic
side
chains. When
dissolved
in
+

The
group
—NH
in
the
zwitterion
acts
as
a
proton
donor
to
the
3
water,
hydroxide
ion
since
it
is
positively
an
amino
acid
with
an
acidic
charged.
side
chain
This
is
behaves
as
a
weak
acid.
–


The
The
group
—COO
amino
acid
is
remains
negatively
negatively
charged.
charged.
because
—COOH
—NH
H
there
groups
are
and
two
only
acidic
one
basic
group.
2
H
+
H
H
N
C
COO
+
OH
H
3
N
C
COO
(+H
2
O)
2
NH
R
C
COOH
2
R
CH
COOH
2
Key points
When

The
amino
acids
which
go
to
make
up
proteins
have
—COOH
and
acid
—NH
dissolved
with
a
in
basic
water,
side
an
chain
amino
behaves
2
groups
which
are
attached
to
the
same
carbon
as
atom.
a
are
weak
two
base. This
basic
NH
is
because
groups
and
there
only
2

The
general formula for
an
amino
acid
is
NH
CH(R)COOH.
2
one

The
R
group
in
amino
acids
can
be
acidic,
basic
or
acidic
—COOH
group.
neutral.
H

The
—NH
group
of
an
amino
acid
interacts
with
the
—COOH
group
to
2
NH
C
COOH
2
form
a
zwitterion,
one
end
of
which
is
positively
charged
and
the
other
(CH
negatively
charged.
)
2
NH
4
2
57
6
Polymers
6.
1
Addition
Learning outcomes
polymerisation
Introduction
Polymers
On
completion
of
this
section,
are
molecules
should
be
able

describe
the
addition
polymerisation
describe
the formation
characteristics
poly(ethene),
and
called
large
molecules
monomers.
built
The
up
process
from
of
a
large
joining
number
monomers
of
small
together
to:
to

very
you
of
form
polymers
is
called
polymerisation .
There
are
two
types
of
polymerisation:

addition
polymerisation

condensation
of
polyvinyl
polymerisation.
chloride
poly(tetrafluoroethene) from
their
monomers.
Addition
In
addition

the
polymerisation
polymerisation:
monomers
free
join
together
by
addition
reactions
(usually
involving
radicals)
Did you know?

Plastics
are
examples
of
word
Greek
‘that
plastic
word
which
is
derived from
‘plastikos’
can
monomers
the
C=C
the
polymer
In
‘that
which
be formed’.
some
have
which
desert
been
can
areas,
planted
to
usually
unsaturated
be
real
trees
improve
planted
containing
the
only
product
of
the
reaction.
In
other
examples of
addition
polymerisation
moulded’.
plastic
help
is
‘trees’
Poly(ethene)
trap
The
monomers
are
ethene,
CH
=CH
2
and
compounds
means

moisture
carbon
the
Some
words,
are
group
polymers.

The
the
the
growth
between
2
of

The
polymer

The
π -bond
is
called
poly(ethene).
The
common
name
is
polythene.
them.
molecule

The
in
each
form
conditions
required

to
is
of
cables:

monomer
chain
needed
low
low-density
a
the
or
poly(ethene)
high
pressure
high-density
and
H
H
H
H
C
C
C
C
H
H
H
H
+
ethene
bonds
plastic
for
of
with
carbon
depends
the
next
atoms
whether
ethene
long.
the
polymer
density:
high
pressures
+
reaction
for
and
and
thousands
high
poly(ethene)
temperature
Figure 6.1.1
for
density
breaks
many
bags
and
temperature
buckets
with
a
and
special
insulation
are
electric
bottles:
lower
catalyst.
H
H
H
H
H
H
H
H
C
C
C
C
C
C
C
C
H
H
H
H
H
H
H
H
monomers
for
required
poly(ethene)
The formation of part of a poly(ethene) chain from three ethene monomers.
The square brackets show the repeating unit.
Y
ou
the
will
atoms
of
notice
monomer
.
the
derived
rather
the
the
Note
than
polymer
repeating
from
polymer
.
ethene
that
The
monomer
that
the
consists
unit
the
in
a
which
repeating
simplest
of
repeating
polymer
when
unit
repeating
the
joined
for
unit
is
derived
smallest
gives
the
poly(ethene)
(CH
).
2
58
units
is
from
group
of
structure
based
on
Chapter
Poly(tetrafluoroethene)

This
polymer
is
used
as
a
6
(PTFE)
non-stick
coating
for
saucepans.
The
most
®
common
commercial
tetrafluoroethene,
brand
CF
F
C
C
F
F
+
is
‘T
eflon
’.
The
monomer
is
2
F
F
C
C
F
F
+
tetrafluoroethene
Figure 6.1.2
PTFE
=CF
2
F
of
F
F
C
C
F
F
F
F
F
F
F
F
C
F
monomers
C
F
F
F
F
F
poly(tetrafluoroethene)
The formation of part of a poly(fluoroethene) chain from three fluoroethene
monomers. The square brackets show the repeating unit.
Polyvinyl
Polyvinyl
chloride
chloride
monomer
is
is
the
common
name
for
CHCl =CH
chloroethene,
.
poly(chloroethene).
Figure
6.1.3
shows
a
The
shorthand
2
way

of
an
writing
‘ n’
is
placed
number

only

an
it
of
the
‘ n’
is
the
is
polymer
in
them
front
to
repeating
placed
repeated
at
be
the
of
the
monomer
to
show
that
there
are
a
large
joined
unit
many
chain:
on
the
bottom
polymer
right
of
is
shown
the
repeating
unit
to
show
that
times.
Cl
H
Cl
n
H
C
C
H
H
Exam tips
Addition
H
H
putting
Figure 6.1.3
polymers
systematically
n
the
by
name
are
named
writing
of
the
poly
then
monomer
A shorthand way of showing the formation of part of a poly(chloroethene)
brackets
after
this.
chain from a large number ‘n’ of monomers
Some
more
examples of
Monomer
Repeating
unit
Polymer
CH
propene,
CH
polymers
3
name
Common
name
poly(propene)
polypropylene
poly(phenylethene)
polystyrene
poly(propenenitrile)
polyacrylonitrile
CH=CH
3
2
2
n
C
phenylethene,
C
H
6
H
6
5
CH=CH
5
2
2
n
CN
propenenitrile,
CNCH=CH
2
2
n
Key points

Polymers
are
molecules

Addition
other

The
by
very
called
the
molecules
polymerisation
addition
repeating
from
large
built
up from
a
large
number
of
small
monomers.
is
when
unsaturated
monomers
bond
to
each
reactions.
unit
in
monomer
a
polymer
which
when
is
the
smallest
joined
gives
group
the
of
atoms
structure
of
derived
the
polymer.
59
in
6.2
Condensation
Learning outcomes
Condensation
A
On
completion
of
this
polymerisation
section,
condensation
be
able
describe
such
the
of
ester
and
an
from
a
the formation
their
and
HCl,
alcohol
carboxylic
are
acid
examples
when
is
two
molecules
eliminated
and
of
COOH
+
CH
3
of
an
(given
alcohol
condensation
OH
Y
CH
3
ethanoic
Terylene
occurs
or
react
off).
and
The
a
small
formation
or
from
an
reactions.
acid
of
For
chloride
example:
polymerisation
CH
describe
O
H
2
characteristics
condensation

as
to:
an

reaction
you
molecule,
should
reactions
acid
COOCH
3
methanol
+
H
3
methyl
O
2
ethanoate
water
nylon-6,6 from
monomers.
CH
COCl
+
CH
3
ethanoyl
OH
Y
CH
3
chloride
COOCH
3
methanol
+
HCl
3
methyl
ethanoate
hydrogen
chloride
Polyesters
Polyesters
make

a
a
polymers
carboxylic
acid)

are
polyester
,
an
we
acid
with
need
with
to
at
many
ester
linkages,
—COO—.
In
order
to
combine:
least
two
—COOH
groups
(a
dicarboxylic
with
alcohol
O
with
at
least
two
—OH
groups
O
(a
diol).
O
O
C
C
Exam tips
monomers:
When
C
dicarboxylic
writing formulae for
polyesters,
make
sure
of
is
round.
the
It
O
O
correct
should
be
C
O
the
C
O
2
way
next
ester
to
O
the COOH
polyester:
group
diol
that
O
the C=O
acid
link
carbon–hydrogen
‘backbone’
derived from
the
Figure 6.2.1
Making a polyester from a diol and a dicarboxylic acid. The boxes represent the
carbon–hydrogen ‘backbone’ in each molecule, e.g. —CH
carboxylic
acid,
O
O
C
C
CH
2
e.g.
CH
2
—
2
Terylene
T
erylene
The
is
made
conditions
temperature
a
H
H
benzene-1,4-dicarboxylic
required
are
catalyst
of
antimony(
H
O
III)
and
ethane-1,2-diol.
oxide
H
and
O
C
C
H
H
acid
a
280 °C.
O
C
H
of
from
C
H
O
H
2
O
H
O
H
2
O
2
b
H
H
C
H
C
H
C
C
C
H
H
O
O
O
C
C
link
Making Terylene; a the monomers; b
unit is shown in brackets.
60
H
H
ester
Figure 6.2.2
O
part of the polymer chain of Terylene. The repeating
Chapter
amide
is
formed
when
a
carboxylic
acid
or
acid
chloride
reacts
with
an
Kevlar
amine.
For
is
COCl
+
CH
3
NH
3
ethanoyl
a
polyamide
chloride
Y
CH
2
CONHCH
3
methylamine
+
acid
HCl
Polyamides
are
polymers
with
many
benzene-1,4-dicarboxylic
with
hydrogen
its
chloride
mass,
than
benzene-1,4-diamine.
amide
linkages,
—CONH—.
it
steel
used for
is ve
and
make
a
polyamide,
we
need
to
times
is re
protective
For
stronger
resistant.
clothing
It
is
such
as
In
bullet-proof
to
by
3
N-methyl
ethanamide
order
made
example:
reacting
CH
Polymers
Did you know?
Polyamides
An
6
vests
and re-resistant
combine:
clothing.

a
carboxylic
acid)

an
acid
with
at
least
two
—COOH
groups
(a
dicarboxylic
with
amine
with
at
least
two
groups
—NH
(a
diamine).
2
monomers:
O
O
C
C
NH
H
dicarboxylic
nylon:
O
O
C
C
acid
+
HO
O
O
C
C
OH
+
HN
H
NH
H
+
etc.
H
diamine
O
O
N
C
N
O
2
H
amide
Figure 6.2.3
H
H
H
link
Making a polyamide from a dicarboxylic acid and a diamide. The boxes represent the
carbon–hydrogen ‘backbone’ in each molecule, e.g. —CH
CH
2
CH
2
—
2
Nylon-6,6
Nylon-6,6
is
made
by
reacting
hexanedioic
acid
with
the
diamide,
1,6-diaminohexane.
Key points

O
O
O
Condensation
O
polymerisation
H
)
2
2
NH
4
C
HO
(CH
2
C
)
2
OH
H
4
)
2
2
NH
4
H
C
O
(CH
2
)
2
C
O
involves
4
loss of
molecule,
H
O
2
H
2
e.g.
a
H
O
small
O or
2
2
HCl, when two types
of

O
O
O
monomer
Polyesters,
)
N
)
4
2
C
)
4
2
N
)
4
2
polyamides,
e.g.
are formed
H
by
Figure 6.2.4
and
C
4
nylon
H
e.g.
O
Terylene
2
react.
condensation
Making nylon-6,6; a The monomers; b Part of the polymer chain of nylon. The repeating unit is
polymerisation.
shown in brackets.

Polyesters
be
The
‘6,6’
in
the
name
of
nylon
refers
to
the
number
of
carbon
atoms
can
made from
in
dicarboxylic
each
monomer
unit.
Different
types
of
nylon
can
be
made
from
acids
and
different
diols.
monomers.

In
the
school
laboratory,
we
can
use
hexanedioyl
Polyamides
be
ClOC(CH
)
4
faster
.
But
COCl
in
place
of
hexanedioic
acid
because
the
reaction
made from
is
dicarboxylic
2
this
method
is
too
expensive
to
be
can
dichloride
used
for
mass
production
acids
and
of
diamines.
nylon.
61
6.3
Monomers
Learning outcomes
and
Simplifying
We
On
completion
should

be
draw
able
a
of
this
section,
to:
polymer from
a
deduce
from
a
a
can
given
or
simplify
given

writing

showing
by
monomer
structures
the
way
of
writing
polymerisation
reactions
by:
you
monomer

polymers
monomers

‘n’
an
at
‘ n’
the
the
drawing
in
front
of
repeating
bottom
each
unit
in
monomer
the
right-hand
continuation
bonds
in
to
polymer
represent
in
square
a
large
number
brackets,
followed
corner
the
polymer
.
polymer.
Example
1:
Addition
polymerisation
of
ethane:
continuation
bond
H
n
C=
C
H
Exam tips
Note
that
water
there
Example
are
molecules
(2n–
2:
eliminated
H
C
C
H
H
H
Condensation
O
1)
H
H
polymerisation
n
to
make
T
erylene:
O
in
n
nHO
CH
2
condensation
because
(2n)
and
(i)
there
(ii)
are
there
is
two
one
O
O
monomers
bond fewer
C
CH
CH
2
than
the
2
polymerisation
number
of
O
+(2n – 1)H
2
O
2
monomers
n
which
combine,
monomers
seven
e.g. for
combining
bonds.
every
there
eight
are
only
From
monomer to
Addition
T
o

draw
polymers,
the
structure
Rearrange
vertically

Draw
single
the
the
polymer
e.g.
of
the
structure
from
the
poly(propene) from
polymer:
if
necessary
C =C
structure
of
propene
the
bond
(see
monomer
to
make
Figure
but
the
atoms
Put
continuation

Put
square

Put
‘ n’
at
bonds
brackets
the
on
both
through
bottom
right
the
of
change
ends
of
the
the
square
CH
n
CH
CH
CH
3
Figure 6.3.1
b
CH
a
the
n
2
polymers
structure
the
be
H
3
H
H
Drawing polypropene; a Rearranging the chain; b
Condensation
will
to
brackets.
H
H
Draw
bond
bonds.
3

double
structure.
continuation
the
a
draw
out
bond.

T
o
stick
6.3.1).
of
structure
eliminated,
the
of
a
n
The polymer
polyester
polymer:
the
e.g.
e.g.
H
for
monomers
—COOH
and
and
identify
—OH
the
in
molecule
the
that
molecules
H
O
2
is

62
eliminated.
Remove
an
an
link.
ester
OH
from
the
—COOH
and
an
H
from
the
—OH
to
make
Chapter

Put
continuation
bonds,
square
brackets
and
‘ n’
around
the
repeat
unit.
6
Polymers
Did you know?
a
Condensation
)
2
polymers
do
not
4
always
have
different
to
be formed from
monomers.
Nylon-6
two
can
be
b
formed
O
(CH
)
2
heating
a
six-sided
ring
O
4
compound
n
little
Figure 6.3.2
by
called
water.
In
caprolactam
this
case
the
with
Drawing a polyester; a The monomers – identifying the atoms eliminated;
unit
b The polymer
of
the
nylon
is
—CONH(CH
)
2
From
polymer to
Addition
T
o

draw
a
repeating
polymers,
the
Identify
structure
the
—.
5
monomer
e.g.
of
the
repeating
poly(phenylethene)
monomer:
unit
in
the
polymer
and
draw
this
without
the
brackets.

Remove

Make
the
the
repeating
continuation
single
unit
C
C
5
C
H
between
double
H
H
6
bond
into
bonds.
H
H
6
the
carbon
atoms
in
the
middle
of
the
bonds.
H
H
C
5
6
C
5
C
C
C
C
C
or
H
H
H
H
H
H
H
6
5
C
C
H
H
n
poly(phenylethene)
C
H
H
6
5
C
C
H
H
phenylethene
Figure 6.3.3
Deducing the monomer of poly(phenylethene)
Condensation
T
o

draw
the
Identify
monomer
polymers
structure
the
of
the
repeating
monomer:
unit
in
the
polymer
and
‘break’
the
bonds
as
follows:
=
O
=
O
Key points
for


Add
back
Make
the
repeating
OH
to
single
unit
the
ester
C =O
bond
into
link
group
between
double
for
and
the
amide
H
to
carbon
link
the
O
atoms
or
in
NH
the
group.
middle
of

We
can
the
showing
bonds.
square
break
draw
formula for
bonds
the
a
simplied
polymer
repeating
brackets
by
units
and
with
continuation
here
bonds.
O
O
C
C
O
O
C
C

N
N
N
The
can
H
H
H
H
be
(i)
O
O
of
HO
C
C
carbon
repeating
monomer
the
the
polymer
single
unit
to
in
atoms
bonds
an
double
of
the
addition
bonds,
or
OH
(ii)
by
adding OH
or
H
to
the
H
end
Figure 6.3.4
a
unit
polymer
H
unit
converting
between
N
of
deduced from
repeating
by
repeating
structure
N
Deducing the monomers of a polyamide. The added OH and H groups are
of
each
repeating
condensation
unit for
a
polymer.
shown circled.
63
6.4
Proteins
Learning outcomes
Polypeptides
Amino
On
completion
of
this
section,
aids
can
condensation
should
be
able
react
with
each
other
to
form
peptides
and
proteins
by
you
reactions.
The
acidic
—COOH
group
in
one
amino
acid
to:
molecule
reacts
with
the
basic
group
—NH
in
another
amino
acid
2

identify
proteins
occurring

units
naturally-
macromolecules
understand
the
as
that
that
amino
acids
condense
molecule.
peptide
are
to form
and
a
a
The
link.
—CO—NH—
When
molecule
polypeptide
of
is
two
group
amino
water
is
formed
acids
react
eliminated.
is
called
like
When
this
an
a
many
amide
link
dipeptide
amino
is
acids
or
a
formed
condense
formed.
proteins.
H
H
H
two
O
O
H
amino
N
C
C
acids
H
H
O
H
O
H
R
R

H
O
2
H
O
C
C
H
H
a
O
dipeptide
N
N
C
C
H
H
O
R
H
R

amide
(peptide)
link
Figure 6.4.1
The
The formation of a dipeptide with the elimination of a water molecule
C—N
bond
conjugative
either
a
side
in
the
amide
(resonance)
of
this
link
link
effect
can
(see
rotate.
does
not
Section
The
rotate
5.3),
amide
freely
but
the
(peptide)
because
C—C
link
of
the
bonds
also
occurs
in
H
H
O
polyamides
C
condense.
H
H
O
such
In
‘monomers’
as
nylon,
naturally
can
be
where
occurring
any
of
20
two
different
peptides
naturally
and
monomers
proteins,
occurring
usually
however
,
amino
the
acids.
CH
3
In
b
H
H
the
laboratory
we
can
make
polymers
from
one
type
of
amino
acid
O
such
C
as
poly(alanine).
stepwise
CH
3
addition
of
Our
body,
various
however
,
amino
acids,
makes
one
at
polypeptides
a
by
the
time.
n
Proteins
Figure 6.4.2
poly(alanine);
The formation of
a The alanine monomer;
Proteins
are
natural
polymers
made
from
20
naturally- occurring
amino
b poly(alanine)
acids.
Protein
hormones
types
of
Proteins
chain
and
may
found
all
protein.
sequence.
primary
is
Each
call
of
of
them
the
are
these
500
sequence
structure
we
muscle,
enzymes
contain
The
in
to
of
has
a
several
amino
acid
thousands
along
amino
the
amino
antibodies.
of
amino
acids
protein
acids
are
of
in
a
chain
part
of
Some
different
acids.
particular
called
a
the
protein
residues.
CH
R

C
O
N
H
CH
R
C
N
H
Part of the primary structure of a protein. R, R′ and R″ represent different
amino acid side chains
64
H
and
sequence
thousand
acids
are
O
N
Figure 6.4.3
blood
There
specific
When
O
R
skin,
proteins.
protein.
amino
hair
,
Chapter
6
Did you know?
It
can
be
acids,
so
time-consuming
their
common
2-aminoethanoic
of
amino
often
acids
the rst
acid.
names
out
are
is
use
glycine, Ala
letters
of
the
the full
often
Biochemists
e.g. Gly
three
writing
is
chemical
used
a
e.g.
glycine
shorthand
alanine,
common
Pro
name
names
way
is
of
of
rather
of
amino
than
writing
proline. This
the
amino
the
names
shorthand
is
acid.
Leu
Pro
Ser
Phe
40
Glu
37
35
Lys
Thr
His
43
38
Glu
42
39
36
41
Figure 6.4.4
Part of the amino acid sequence of the blood pigment myoglobin from a
sperm whale. The letters in each circle are shorthand for particular amino acids. The
numbers represent the position of the amino acid residues in the chain.
Exam tips
You
should
be
able
to
—NH—CH(R)—CO—
chain.
In
R
represents
living
into
then
a
by
a
tripeptide
tetrapeptide
proteins
or
one
organisms,
proteins
recognise
20
different
enzymes
complex
four
than
side
catalyse
series
(containing
more
repeating
unit
in
—CH(R)—CO—NH—. This
of
(containing
contain
the
of
three
the
amino
acid
chain.
protein
unit
as
repeats
along
the
chains.
condensation
reactions.
amino
one
a
A
acids
residues),
residues)
The
of
dipeptide
and
so
individual
amino
is
first
then
on.
chains
acids
formed,
a
Some
are
called
polypeptides.
Did you know?
Wool
of
is
a
protein bre
hydrogen
with
a
helical
structure
wool
clothes
regular
is
washed
may
by
a
regular
arrangement
bonds.
hydrogen
If
joined
then
at
too
lose
high
their
a
temperature,
shape
because
bonds
the
the
hydrogen
hydrogen
bonds
bonds
break. The
reform
in
a
less
way.
Key points

Proteins

The

Proteins

The
are
naturally
‘monomers’ for
are formed
linkage
in
occurring
proteins
by
proteins
polymers.
are
amino
sequential
is
the
acids.
condensation
amide
(peptide)
reactions.
link.
65
6.5
Carbohydrates
Learning outcomes
Carbohydrates
Carbohydrate
On
completion
of
this
section,
simple
should
be
able
carbohydrates
carbohydrates
naturally
occurring
as
complex
C
H
understand
that
the
simple
monomers
12
.
Even
2
For
So
the
example,
general
the
formula
molecular
for
most
formula
for
y
simple
carbohydrates
such
as
glucose
are
quite
6
carbohydrates
contain
several
—OH
groups.
For
the
purposes
of
sugars
the
polymerisation
of
carbohydrates
we
can
write
a
simple
which
carbohydrate
condense
water
.
.
molecules.
understanding
are
O
O)
molecules
Many

with
(H
C
x
is
6
identify
carbon
is
to:
glucose

means
you
in
a
simplified
form
as
HO— —OH.
to form

Simple
sugars
such
as
glucose
and
fructose
are
called
monosaccharides
polysaccharides
because

identify
pectin
cellulose,
as
starch
examples
they
contain
one
sugar
unit
(mono
means
one
and
saccharide
and
means
sugar).
Sugars
containing
of

two
simple
sugar
units,
e.g.
sucrose
are
called
polysaccharides.
disaccharides.

containing
Formation of
H
H
Sugars
C
OH
The
C
simple
sugar
units
are
called
polysaccharides.
polysaccharides
polymerisation
polymers
many
of
monosaccharides
(polysaccharides )
is
an
such
example
of
as
glucose
to
form
condensation
O
H
H
polymerisation.
W
ater
is
eliminated.
A
simplified
diagram
of
this
process
H
is
C
shown
OH
H
C
C
H
OH
OH
OH
HO
a
OH
Figure
6.5.2.
HO
simplified
monosaccharide
structure
a
in
C
glucose
for
molecule
glucose
O
O
2
Figure 6.5.1
A glucose molecule
polysaccharide
Figure 6.5.2
Monosaccharide molecules condensing to form a polysaccharide. The
monosaccharide is shown as HO——OH.
The
C—O—C
The
empirical
(C
H
6
O
10
)
5
i.e.
linkage
in
formula
glucose
these
for
a
with
sugar
polymers
polysaccharide
water
is
made
called
from
a
glycosidic
glucose
link.
is
removed.
n
Naturally-occurring
Polysaccharides

as
storage

in
plant

as
a
found:
carbohydrate
cell
‘glue’
are
polysaccharides
walls
(starch
in
plants
and
glycogen
in
animals)
(cellulose)
between
plant
cell
walls
(pectin).
Exam tips
These
You
the
are
not
exact
expected
structure
of
to
remember
are
such
as
expected
glucose.
to
polymerisation,
know
the
But
to form
how,
—OH
are
that
water
is
during
living
organisms
using
enzymes
as
all
made
by
condensation
polymerisation.
Starch
a C—O—C
provides
us
with
most
of
the
carbohydrate
in
our
diet.
It
is
a
bond
of
hundreds
of
glucose
units.
It
can
form
chains
or
branched
eliminated.
chains.
66
in
groups
polymer
and
made
you
Starch
condense
are
simple
They
sugars
polysaccharides
catalysts.
The
glucose
monomers
polymerise
by
the
—OH
groups
at
the
Chapter
1-
and
in
position
also
4-positions
6
happen
leads
to
a
is
condensing
always
between
branched
a
6
5
on
the
the
and
—OH
chain
of
b
C
side
groups
form
C
eliminating
same
at
water
.
the
the
chain.
1-
and
Note
that
the
group
Polymerisation
6-positions.
can
This
starch.
6
6
6
6
O
4
4
C
C
C
1
4
1
4
O
1
1
4
O
1
O
O
C
2
3
Figure 6.5.3
of
6
The simplied structure of starch; a The numbering of the carbon atoms in a
glucose molecule; b A simplied diagram of part of a starch chain showing the α-1,4-linkages
Did you know?
Glucose
isomers
has
of
several
chiral
glucose. The
α-D-glucopyranose.
ring
In
centres
form
(see
used
addition
for
Section
starch
glucose
1.6). There
synthesis
exists
in
a
is
chain
are
several
optical
called
form
as
well
as
a
form.
Cellulose
Cellulose
is
responsible
called
the
also
for
made
this
β-glucose.
ring
have
position
6
is
a
In
from
this
different
not
glucose
polymerisation
always
isomer
,
the
position
on
the
monomers.
act
on
—H
in
a
and
space.
‘same
—OH
In
side’
of
1
4
atoms
the
(see
chain
that
of
in
the
are
glucose
position
group
4
of
in
Figure
6.5.4).
6
O
4
enzymes
isomer
cellulose,
6
6
O
1
4
1
4
O
1
4
1
O
O
6
6
Figure 6.5.4
The
different
The simplied structure of cellulose. Note that the β-1,4-linkages cause the
group in the 6 position to alternate in the chain.
Pectin
Pectin
to
is
make
found
jam
between
set.
The
methylglucuronic
OH
—CH
group
acid.
at
the
walls
monomer
This
is
position
6
of
for
plant
the
similar
in
cells.
It
formation
to
glucose
glucose
is
is
used
of
except
replaced
commercially
pectin
by
is
that
a
the
Key points
—COOCH
2
group.
3
The
link
is
a
β-1,4-link
as
in
cellulose.

Polysaccharides
occurring
3
3
monomers
O
1
4
1
of
simple
sugars.
O
4
1
O
4
1

O
The
monomers
in
polysaccharides
COOCH
COOCH
3
Figure 6.5.5
naturally-
made from
COOCH
COOCH
4
are
polymers
glucose
3
The simplied structure of pectin. Note that the β-1,4-linkages cause the

group in the 6-position to alternate in the chain.
The
or
linkage
between
called
a
are
glucose
in
the
usually
esters.
polysaccharides
sugar
glycosidic
units,
—O—
is
link.
Did you know?

Starch
and
cellulose
are
glucose
polymers.
Scientists
have found
microorganisms.
hydrogen
If
a
this
produced
way
of
producing
method
could
be
can
used
be
as
hydrogen from
modied
a fuel for
on
cars.
an
cellulose
industrial
using
scale,
the

Pectin
is
a
polymer
methylglucuronic
of
acid.
67
Exam-style
Answers to
all
exam-style questions
can
questions
be found on the
Which
a
types
of
species
heterolytic ssion
of
best
a
1
B
describe
covalent
Module
accompanying CD.
Multiple-choice questions
1
–
the
bond
products
in
a
of
C
diatomic
CH
CH
2
2
molecule?
A
electrophiles
B
atoms
C
electrophiles
D
nucleophiles
and
nucleophiles
D
CH
3
and free
radicals
and free
and
radicals
atoms
Structured questions
2
What
is
the
UPAC
name for
the
compound
below?
6
CH
C(CH
3
)ClCH
3
A
2,2-chloromethyl
B
2-chloro-2-methyl
C
2-
D
4-chloro-4-methyl
CH
2
a
CH
2
Explain
ii
3
pentane
b
A
difference
hydrocarbon,
of
pentane
the
between
i
i
pentane
crude
oil
Write
has
P,
present
as
a
the formula C
minor
of
Which
of
the following
homologous
the
constituent
H
8
displayed formulae
of
three
isomers
P.
[3]
pentane
ii
3
and
[2]
4
methyl-2-chloro
empirical
structural formulae.
are
properties
of
One of these isomers, when treated with hot
a
acidied potassium manganate(VII), produced
series?
two compounds,
Q (C
H
3
O) and
R (CH
6
O).
2
i
Members can be represented by a general formula.
Show the steps involved in the mechanism of
ii
Members
possess
similar
the reaction between
iii
Members
possess
the
iv
Members
differ
by
chemical
same
properties.
c
group.
a CH
Q and HCN. Use curved
arrows to show the movement of electrons.
empirical formulae.
The
product formed
by
the
reaction
in
b
[5]
ii
2
exhibits
A
i,
ii,
iii
B
i,
ii,
iv
i
isomerism.
State
the
type
of
isomerism
and
its
characteristic feature.
C
i,
ii
D
[2]
ii
ii,
Draw
the
displayed formulae
of
the
isomers
iv
involved.
4
Which
of
the following
distinguish
between
reagents
can
compounds
A
be
and
used
iii
to
State
the
[2]
property
which
allows
them
to
be
identied.
B?
7
O
a
i
Explain
[1]
the
meaning
of
addition
O
CH
CH
3
polymerisation.
C
H
CH
A
acidied
ii
Tollen’s
iii
Brady’s
iv
NaCN
A
i
and
B
i
C
ii
D
and
A, forms
a
polymer
(polystyrene).
CH
manganate(VII)
CH
2
reagent
reagent
(aq)
and
A
dilute
HCl
Draw
the
involving
iii
iv
and
ethene,
polyphenylethene
B
potassium
Phenyl
3
ii
and
iii
ii
C CH
3
i
[2]
2
of
part
repeating
of
the
polymer
units.
[2]
b
Dene the term ‘condensation polymerisation’.
c
The
a
iv
structure
three
structure,
polymeric
B,
represents
the
repeating
unit
[2]
of
substance.
H
CH
O
O
3
5
On
complete
0.264 g
Which
of
of
combustion
carbon
dioxide
the following
a
hydrocarbon
and
0.054 g
compounds
of
produced
N
water.
correctly
C
C
N
CH
C
2
H
satises
H
B
this
A
analysis?
i
Name
ii
Deduce
the
link
2
in
B.
[1]
2
the
monomers
68
present
CH
structural formulae
used
to form
the
of
the
polymer.
[4]
Module
c
Using
your
explain
and
d
List
ii
knowledge
the
difference
thermosetting
two
classes
of
of
their
reaction
between
i
to
heat,
polymers.
naturally
10
thermoplastic
Eugenol
from
[2]
is
an
cloves.
aromatic
ts
1
Exam-style
liquid
which
structural formula
can
is
questions
be
extracted
represented
below:
OCH
occurring
3
macromolecules.
[2]
CH
2
8
Combustion
gave
2.20 g
contains
of
of
1.00 g
carbon
carbon,
of
an
organic
dioxide
hydrogen
and
and
compound,
1.21 g
oxygen
of
R,
water.
only.
R
1.00 g
a
of
Describe
with
how
you
would
the following
expect
reagents,
eugenol
drawing
to
react
structural
3
R
occupied
a volume
a
Calculate
b
Deduce
c
R
the
of
at
373 cm
s.t.p.
empirical formula
of
formulae
R.
[5]
i
the
reacts

molecular formula
with
the following
methanoic
of
R.
conc.

alkaline
i
State
iodine
Write
dichloride
ii
Br
iii
Br
State
[2]
4
[3]
a
between
the following
simple
laboratory
pairs
of
R
and
give
reasons for
OH
and
CH
CO
3
your
represent
the
reactions
two
would
ester
of
a
with
reagents
be
listed
observed
of
the
by
aqueous
the nal
monohydric
monocarboxylic
distinguish
H
[3]
2
of
and
organic
above.
Cl
and
CH
CH
draw
acid
sodium
is
reagent
alcohol
hydroxide.
[3]
the
product
listed
and
completely
Cl
2
[4]
iii
An
to
compounds:
[2]
to
displayed formula
9
test
of
solution.
the rst
formed
[2]
acid
name
what
relevant
(aq)
3
iii
any
2
equations
with
giving
oxide, SOCl
Describe
ii
R
and
(l)/CCl
2
conclusion.
ii
sulphur
reagents:
i
the
products
2
acid
sulphuric
the
[2]
b

of
observations.
above.
and
[3]
[2]
a
hydrolysed
1.63 g
of
the
ester
–2
required
a
2.2
moles
10
i
Calculate
ii
Suggest
the
formula
of
iii
Draw
with
b
×
i
ii
the
State
in
a
the
the
name
the
the
and
hydroxide.
mass
draw
of
the
the
ester.
[2]
of
one
other
was
of
reaction
replaced
industrial
[1]
involved
by
an
oil
signicance
if
the
The
to
ester
A,
ester
or fat.
of
this
[1]
type
reaction.
c
ester
molecular formula.
type
[2]
structural
ester.
displayed formula
above
State
sodium
molecular
same
the
of
of
[1]
below,
the following
reacts
with
ethanol
according
equation:
O
O
C
H
2
OH
C
OH
5
OR
OC
H
2
5
A
i
Give
the
name
of
the
process
involved
in
reaction.
ii
d
Explain
When
a
organic
i
[1]
its
industrial
mixture
irradiated
with
of
the
importance.
ethane
ultraviolet
products
Give
and
[2]
chlorine
light
a
is
number
One
the
sh
of
of
of
the
process
involved
in
this
[1]
the
products
mechanism
hook
of
are formed.
name
reaction.
ii
this
chloroethane.
involved
notation
electrons.
is
to
in
its
describe
Explain
production. Use
the
movement
[4]
69
7
Data
7
.
1
Analysis
analysis
Learning outcomes
of
and
scientific
Accuracy
When
On
completion
of
this
section,
we
be
able
apply
the
appropriate
analysis
understand
‘standard

of
concepts
scientic
to
between
and

out
chemical
collecting
data
experiments
relevant
to
such
reaction
as
titrations,
rates,
we
need
gravimetric
are
very
the
terms
the
the
‘mean’
measurements
close
to
the
true
are
accurate
or
not.
Accurate
to
know
measurements
value.
can
get
accurate
data
by:
and
difference
terms
our
data
deviation’
understand
precision
to:
Y
ou

carry
or
whether

and
data
you
analysis
should
measurement
‘precision’

repeating
the
measurements
many
times

repeating
the
measurements
using

using
measuring
instruments
which

using
measuring
instruments
carefully.
different
are
instruments
very
accurate
‘accuracy’
calculate
the
mean
and
standard
Precision
deviation from
data
means
how
close
the
measurements
are
to
each
other
.
If
the
provided.
measurements
An
idea
Figure
of
the
7.1.1,
are
very
close
difference
where
the
to
each
between
results
other
,
accuracy
of
different
they
and
are
precise
precision
titres
are
is
shown
in
shown.
3
3
23 cm
23 cm
true
3
3
value
24 cm
24 cm
3
3
25 cm
Figure 7.1.1
25 cm
The black lines across the burette in a and b show four different burette
readings for the same experiment; a The results are precise but not accurate; b The results
are accurate (because the average is close to the true value) but not precise.
Exam tips
When
of
n
thinking
shooting
a
the
at
shots
about
a
the
target
are
difference
may
precise
between
accuracy
and
precision,
the
idea
help.
but
not
accurate.
n
b
the
shots
are
accurate
but
not
precise.
a
A
set
close
70
of
to
repeat
the
b
readings
true
value
in
and
chemistry
be
should
precise.
have
a
mean
(average
value)
Chapter
7
Data
analysis
and
measurement
Mean value
The
of
mean
is
identical
average

A

The
temperature

The
experiment
The
fuel
the
is
results
of
experiments.
used
for
to
the
heat
a
rise
is
the
For
numbers
xed
is
volume
measured
repeated
ve
experiments
Experiment
of
after
rise/
10.1
°C
+
mean
+
data
in
a
number
water
.
a
set
time.
2
14.2
3
12.0
+
13.5
4
14.2
+
12.7
is
5
13.5
12.7
62.5
________________________________
The
the
are:
10.
1
12.0
from
times.
1
Temperature
taken
example:
_____
=
=
5
12.5 °C
5
Standard deviation
Standard
the
A
deviation
mean.
high
range.
A
low
value
The
normal
shows
we
a
measure
shows
that
standard
variation
chemistry,
is
value
the
use
data
deviation
expected
the
of
that
is
from
‘sample
how
the
points
only
the
spread
data
out
points
are
spread
‘signicant’
measuring
standard
the
are
out
if
numbers
close
it
to
over
falls
The
from
mean.
wider
outside
instruments
deviation’.
a
are
the
used.
equation
the
In
we
use
is:
2
S
(x
=
x)
N
n – 1
S
is
the
sample
standard
deviation
N
x
is
each
x
is
the
individual
piece
of
data
mean
2
Σ
is
the
sum
n
is
the
number
The
standard
Worked
In
a
of
(x
x)
of
individual
deviation
has
pieces
the
same
titration
four
titres
standard
data.
units
as
the
data
used.
example
experiment
to
nd
the
3
of
of
are:
;
19.6 cm
concentration
3
20.0 cm
of
an
3
;
20.2 cm
;
alkali,
the
values
Key points
3
19.4 cm
.
Calculate
the
deviation.

19.6
+
20.0
+
20.2
+
Step
1
Find
the
The
mean
is
the
average
of
a
19.4
_________________________
3
=
mean:
sample
19.8 cm
of
data.
4

Step
2
Find
the
sum
of
the
squares
of
the
differences
from
the
Standard
of
2
(19.6
0.04
–
+
19.8)
0.04
2
+
+
(20.0
0.16
+
–
2
19.8)
0.16
+
=
(20.2
–
19.8)
how far
3
Divide
by
n
–
1,
i.e.
0.40
÷
3
(19.4
–
19.8)
0.40
=
the
data
is
a
measure
deviates from
2
+
the

mean.
Precision
the
Step
deviation
mean:
data
refers
values
to
how
are
closely
grouped
0.13
together
–
the
closer
the
values,
_____
the
3
Step
4
T
ake
This
could
the
square
root:
√
0.13
=

be
considered
quite
a
high
standard
deviation
as
we
can
3
burette
to
an
accuracy
of
at
least
the
precision.
Accuracy
0.1 cm
refers
to
the
closeness
read
of
the
greater
0.36 cm
the
data
values
to
the
true
3
and
perhaps
to
0.05 cm
.
A
value.
second
example
is
given
in
Section
8.1.
71
7
.2
Accuracy
Learning outcomes
in
measurements
Errors
There
On
completion
should

be
able
assess
in
the
this
select
make
of
section,
degree
of
uncertainty
associated
laboratory
appropriate
are
practical
three
main
chemistry
causes
of
errors
in
practical
chemistry:
you
to:
measurements
pieces

of
in
with

mistakes

faults

limitations
in
in
calculations,
laboratory
of
the
including
mistakes
with
signicant
gures
equipment
apparatus
used.
apparatus
apparatus
measurements
to
Weighing
depending
3
For
on
the
degree
of
making
up
small
quantities
e.g.
500 cm
of
solutions
for
titrations,
we
accuracy
need
to
weigh
to
an
accuracy
of
±0.01 g.
For
accurate
gravimetric
work
an
required.
accuracy
that
is
(mass
of
±0.001 g
measured
of
or
±0.0001 g
is
needed.
It
is
always
the
loss
of
mass
i.e.
weighing
bottle
+
chemical)
–
(mass
of
weighing
bottle
alone)
Exam tips
Did you know?
1
When
using
an
accurate
in
weighing
balance,
The
inaccuracies
can
earliest
alley
caused
by
air
draughts
or
marks
on
the
of
a
balance
dates from
over
4000
years
ago from
the
ndus
in
present
day
Pakistan.
Simple
beam
balances for
accurate
weighing
greasy
have
nger
record
be
been
present
in
chemistry
laboratories
since
the
19th
century. The
weighing
modern
day
balance for
accurate
work
should
really
be
called
an
analytical
bottle.
scale
2
t
is
out
of
bad
an
practice to try to weigh
exact
solid to
amount,
make
–3
e.g.
0.
1 mol dm
.
an
e.g.
exact
than
rather
than
an
gravitational
analytical
balance. This
is
because
it
measures force
rather
mass.
1.30 g
solution,
Volumes
Pieces
of
and temperatures
laboratory
maximum
errors.
glassware
A
have
calibration
calibration
mark
is
a
line
marks
on
the
which
guarantee
glassware
that
3
shows
a
usually
shows
used
particular
measured
some
in
value
at
typical
most
a
of
volume,
particular
errors
for
e.g.
temperature
some
pieces
of
(usually
class
Maximum
3
B
volumes
20 °C).
titration
are
The
table
apparatus
error
3
standard ask
±0.8 cm
3
250 cm
3
standard ask
±0.3 cm
3
50 cm
3
burette
±0.
1 cm
between
3
25 cm
Pieces
These
schools.
Apparatus
1 dm
.
100 cm
any
two
marks
3
volumetric
of
pipette
glassware
such
as
±0.06 cm
large
measuring
cylinders
are
much
more
3
inaccurate,
accurately.
If
±1 cm
The
temperatures
play
are
a
part
in
available
only
72
e.g.
read
to
They
graduation
are
the
to
be
overall
which
the
.
read
nearest
should
marks
on
measured,
accuracy
to
of
be
used
beakers
the
the
±0.01 °C,
degree
not
accuracy
most
measuring
even
of
more
the
experiment.
but
Celsius.
are
for
volumes
inaccurate.
thermometer
Some
laboratory
may
thermometers
thermometers
Chapter
Overall
experimental
Experiments
apparatus
should
be
7
accuracy
designed
to
get
the
best
accuracy
out
of
the
available.
3

Burette
error
masses
measured
volumetric

The
the
best
a
The
to
of
having
nearest
overall
0.5–1%.
precision
overall
apparatus
the
by
titres
0.01 g
that
and
are
above
volumes
30 cm
measured
,
with
a
pipette.
concentration

minimised
accuracy
order
with
is
So
greater
to
three
accuracy
that
approximately
is
least
a
than
school
is
the
this.
a
point
For
solid
It
to
is
in
of
be
likely
nal
value
decimal
to
be
in
results
a
incorrect.
depend
little
three
only
quoting
would
will
is
quoting
example,
gures
experiment
accurate.
of
laboratory
little
signicant
of
1 gram
in
there
on
the
piece
of
weighing
places,
if
the
accuracy
3
of
the
container
100 cm
you
are
making
a
solution
of
the
solid
in
is
3
accurate

When
to
making
volume
of
Similarly,
that
to
prepare
a
solutions,
solution
in
it
a
is
more
accurate
volumetric
larger
smaller
quantities
ask
of
a
to
make
than
a
up
small
substance
is
a
large
volume.
more
accurate
quantities.
solutions
solution
the
the
1 cm
weighing
up
prepare
solute
a
weighing
Making
T
o
only
of
required
known
degree
of
concentration,
accuracy
and
we
use
need
a
to
weigh
volumetric
out
ask
the
to
solution.
3
T
o
make
of
200 cm
a
solution
of
known
concentration,
the
procedure
is:
3

Tip
the
solid
from
the
weighing
bottle
into
a
200 cm
beaker
.
3

Add
about

Shake

W
ash

Pour
of
50 cm
pure
water
.
ground
well
out
the
to
the
dissolve
the
volumetric
solution
from
solid.
ask
the
glass
stopper
with
beaker
a
little
into
pure
the
water
.
volumetric
ask
using
a
funnel.
meniscus

W
ash
out
washings

W
ash
with

Fill

Add
out
a
the
to
the
the
any
little
beaker
several
times
with
pure
water
and
add
calibration
the
mark
ask.
liquid
pure
remaining
in
the
funnel
into
the
volumetric
ask
water
.
volumetric
ask
with
pure
water
to
just
below
the
meniscus.
3
200 cm
water
dropwise
until
the
bottom
of
the
meniscus
is
on
the
20 ºC
calibration

Put
the
mark.
stopper
(bung)
on
the
ask
and
shake
gently.
Figure 7.2.1
A volumetric ask used to
make a standard solution
Key points

Pipettes,
known

The
burettes
maximum
overall
and
volumetric asks
have
calibration
marks
with
a
error.
accuracy
is
dependent
on
the
piece
of
apparatus
that
is
least
accurate.

n
to
volumetric
the
analysis,
appropriate
weighing
number
of
and
measuring
volumes
signicant gures for
the
should
overall
be
made
accuracy
required.
73
7
.3
Standards
Learning outcomes
Introduction
We
On
completion
of
this
section,
compare
values.
should
be
able
understand
selecting

identify
We
have
quantities
already
met
and
terms
measurements
such
as
in
standard
terms
electrode
of
standard
potential
to:
and

chemical
you
the
criteria
primary
the
use
used
in
standard
carbon-12
enthalpy
scale.
In
change .
Relative
atomic
mass
is
measured
on
the
addition:
standards
of
NaHCO

Standard
temperature

Standard
pressure
is
298 K.
,
3
Na
CO
2
,
KO
3
salts
as
,
(COOH)
3
and
primary
understand
preparation

understand
criteria for
of
101 325 Pa.
standards
Primary

is
its
2
standard
the
use
of
standards
used
in titrations
the
solutions
calibration
In
order
prepare
to
nd
the
standard
titrating
an
concentration
solutions
unknown
of
alkali
of
a
known
with
solution
by
titration,
concentrations.
hydrochloric
acid,
For
we
we
need
example,
need
to
to
when
know
the
curves.
concentration
of
the
acid
to
at
least
two
signicant
gures,
e.g.
–3
.
0.014 mol dm
by
A
titrating
primary
it
We
with
make
a
standard
sure
primary
for
use
that
the
acid
has
the
correct
concentration
standard.
in
titrations
is
a
chemical
with
the
following
properties:

The
solid

It
must
be
stable

It
must
be
readily

It
must
give

It
should
Primary
alkalis,
must
able
in
to
obtained
to
a
very
high
purity.
air
.
preferably
standards
be
soluble
reproducible
reducing
Some
be
can
be
examples of
a
high
used
or
water
results
have
agents
in
to
and
in
a
form
nd
stable
solution.
titration.
relative
oxidising
a
the
molecular
exact
mass.
concentrations
of
acid,
agents.
primary
standards
Did you know?
The
For
of
the
highest
99.9999%
standard. All
calibrated
accuracy
purity
other
against
is
work,
used
as
standards
silver
table
shows
laboratory.
All
some
of
primary
these
standards
standards
are
commonly
available
to
a
used
high
in
the
level
of
purity.
a
are
Primary
standard
Used to
standardise
this.
sodium
carbonate,
CO
Na
2
sodium
acids
3
hydrogencarbonate
potassium
iodide,
acids
sodium
KO
thiosulphate
3
ethanedioic
acid
(oxalic
acid),
bases
(COOH)
and
some
oxidising
agents
2
potassium
‘cell’
dichromate(VI),
Cr
K
2
meter
sodium
chloride,
O
2
reducing
NaCl
Standardising
agents
7
silver
solutions
used
in
nitrate
colorimetry
light
light
filter
coloured
sensitive
cell
Colorimetry
source
coloured
Figure 7.3.1
74
is
an
easy
and
quick
way
of
nding
the
concentration
of
solution
A colorimeter
shows
a
solutions
simplied
(see
Unit
diagram
1
of
Study
a
Guide ,
colorimeter
.
Section
7.1).
Figure
7.3.1
Chapter
The
electric
intensity
of
current
light
instrument,
we
have
to
it
must
see
how
concentrations

making
a
accurate

taking
The

a
the
of
set
be
the
cell
on
of
meter
a
In
order
placed
of
is
of
proportional
cell.
to
the
Before
calibrate
change
in
known
standard
readings
meter
readings
are
solutions
meter
the
light-sensitive
calibrated.
the
of
on
the
solutions
dilution
procedure
Put
registered
falling
when
cell.
different
to
the
using
the
7
the
colorimeter
,
different
This
is
done
by:
concentrations
by
solution
each
solution.
is:
containing
the
pure
solvent
used
to
make
the
solutions
into
colorimeter
.

Adjust

Put
a
the
cell
meter
reading
containing
a
to
zero.
solution
of
known
concentration
into
the
colorimeter
.

Record
the

Repeat
these
The
meter
meter
reading.
steps
readings
for
are
other
then
solutions.
plotted
against
the
concentrations
of
the
solutions.
For
ver y
dilute
proportional
coloured
to
concentrated,
concentration.
of
the
the
the
Figure
concentration
meter
We
coloured
solutions,
can,
reading
from
of
reading
solution.
not
nd
the
meter
the
may
however,
solution
the
the
be
If
is
likely
the
values
of
the
cur ve
be
solutions
proportional
calibration
to
to
are
the
concentration
as
shown
in
7.3.2.
1.0
retem
)ecnabrosba(
gnidaer
0.8
0.6
0.4
0.2
0
0
1
2
3
4
5
6
–3
concentration/10
Figure 7.3.2
Calibration curve for a coloured solution. The concentration of the coloured
–3
more
information
about
3
mol dm
solution at meter reading 0.8 is 4 × 10
For
7
–3
mol dm
.
colorimetry
see
Section
9.2.
the
concentration
Key points

Primary
or

Na
are
substances
CO
2

standards
other
is
used
as
a
used
used
to
in
calculate
of
acids,
alkalis
titrations.
primary
standard
to
standardise
acids.
3
KO
can
be
used
to
standardise
sodium
thiosulphate.
3

(COOH)
can
be
used
to
standardise
bases.
2

K
Cr
2

O
2
When
can
making
measuring

When
made
be
used
to
standardise
reducing
agents.
7
to
up
the
measuring
to
a
solutions
required
of
known
degree
concentrations
calibration
curve for
of
concentration, asks
accuracy
using
the
a
should
colorimeter,
be
and
balances
selected.
reference
should
be
instrument.
75
8
Titrations
8.
1
Principles
Learning outcomes
and
of
completion
of
this
section,
titration
be
able
is
of
understand
used
to
determine
unknown
the
amount
concentration.
This
of
is
substance
the
present
procedure
in
a
for
to:
determining

a titration
you
solution
should
analysis
titrations
Carrying out
A
On
gravimetric
the
basic
principles
the
concentration
of
a
solution
of
alkali:
of

Fill
a
the
acid).
burette
with
acid
of
known
concentration
(after
washing
it
with
titration.

Record

Put

Add
an

Add
the
a
colour

the
the

burette
volume
acid–base
acid
(end
Record
burette
initial
known
the
of
reading.
alkali
indicator
slowly
from
into
to
the
the
the
flask
alkali
burette
in
until
using
the
a
volumetric
pipette.
flask.
the
indicator
changes
point).
nal
burette
reading
(nal
–
initial
burette
reading
is
called
titre).
Repeat
the
process
until
two
or
three
successive
titres
differ
by
no
3
more
than
0.10 cm
acid
Titres
and
standard deviation
volumetric
pipette
For
our
results,
we
take
successive
titres
which
differ
by
no
more
than
3
0.10 cm
be
sure
below,
alkali
This
that
the
gures
white
.
is
gives
the
4th,
us
a
standard
experiment
5th
and
6th
is
deviation
very
titres
which
accurate.
would
be
For
is
very
example
selected.
The
low
in
so
the
mean
we
can
table
of
these
32.30.
and
tile
indicator
Figure 8.1.1
Rough titre
The apparatus used in an
2nd titre
3
3rd titre
4th titre
3
3
32.85 cm
32.95 cm
5th titre
6th titre
3
32.00 cm
3
32.25 cm
3
32.35 cm
32.30 cm
acid–alkali titration
The
standard
deviation
(see
page
71)
for
these
2
(32.25 – 32.30)
three
titres
is:
2
+ (32.35 – 32.30)
2
+ (32.30 – 32.30)
2
3
The
standard
low.
If
we
deviation
took
the
2nd
for
to
the
6th
4th
to
titres,
6th
titres
however
,
is
0.05 cm
the
,
standard
which
is
deviation
very
is
3
much
higher:
0.31 cm
Titrimetric technique
Using
a
pipette
A
volumetric
it
is
lled

Have

Using
to
the
a
sucking

Fill
the
mark.
76
pipette
its
is
designed
calibration
solution
pipette
some
ller
,
of
pipette
that
it
again
is
to
wash
up,
to
mark.
so
the
be
out
then
deliver
When
used
the
letting
liquid
a
xed
using
in
a
drain
level
volume
of
liquid
when
pipette:
beaker
.
pipette
it
a
is
with
out
just
the
into
solution
the
above
by
sink.
the
calibration
Chapter

Remove

Bring
the
pipette
from
the
8
beaker
.
Exam tips
the
solution
meniscus
just
level
touches
down
this
to
the
calibration
mark
so
that
the
mark.
When

Run
the
contents
of
the
pipette
into
the
clean
titration
flask
(or
a
with
pure
Allow
with
the
the
pipette
side
of
pipette:
When
sucking
up
the
solution,
water).
keep

a
flask
1
washed
using
to
the
drain
flask
completely
after
the
by
keeping
solution
has
the
been
tip
in
contact
the
the
tip
surface
of
of
the
the
pipette
below
solution
to
delivered.
avoid
air
bubbles
entering
the
pipette.
Using
a
burette
2
When
using
a
Don’t
of

Rinse
the
solution

Clamp

Using
with
burette
to
the
a
burette
drain
with
tap
and
the
through
burette
funnel,
the
blow
out
the
tiny
amount
burette:
vertically
add
open.
make
solution
the
a
little
Close
sure
tip
and
of
the
that
be
the
put
the
tap
to
of
a
are
in
it
then
allow
the
the
remaining
in
the
tip
of
pipette.
burette.
beaker
solution
while
there
used
solution
to
there
no
air
beneath
be
is
used
still
the
to
the
liquid
bubbles
in
burette.
burette
in
the
the
tip
of
the
burette.

Fill
the

Adjust
mark.
burette.
the
level
Make
meniscus
Remove
of
sure
(see
the
funnel.
meniscus
that
Figure
the
you
take
to
meniscus
a
the
denite
reading
graduation
from
the
(calibration)
bottom
of
calibration
marks
the
8.1.2).
Figure 8.1.2

Place

T
urn
the
titration
flask
and
its
contents
below
the
Reading a burette. Your eye
should be level with the bottom of the
burette.
meniscus.
the
burette
left-handed).

Run
to

in
the
tap
This
with
leaves
solution
your
the
from
left
hand
(or
other
hand
free
the
burette
while
right
to
hand
shake
shaking
if
you
the
the
are
flask.
flask
from
side
side.
When
doing
solution
approached.
too
high
accurate
from
a
the
This
value
(rather
burette
prevents
for
the
than
one
rough)
drop
you
at
a
titrations,
time
overshooting
when
you
the
must
end
add
point
the
endpoint
and
the
end
more
the
is
getting
titre.
Exam tips
When
using
a
burette:
1
The
titration flask
2
The
meniscus
is
is
put
seen
on
more
a
white
clearly
tile
if
a
to
make
piece
of
white
point
card
is
placed
visible.
behind
it.
3
The flask
is
arranged
so
that
the
burette
tip
is
just
inside
the
mouth
of
the
flask.
Key points

Acid–base
colour

When
titrations
rapidly
at
the
processing
are
carried
end
out
using
an
indicator
which
changes
point.
titration
results,
the
values
selected
should
be from
two
3
or
three
successive
titres
whose
values
are
no
more
than
0.
10 cm
apart.
77
8.2
Titrimetric
Learning outcomes
completion
of
this
section,
be
able
is
sometimes
understand
back

back
the
basic
principles
of
titrations
perform
In
a
easier
back
to
do
a
titration,
titration
a
in
known
reverse.
amount
This
of
a
is
called
standard
a
back
reagent
is
to:
added

titrations
you
titration.
should
back
Back titrations
It
On
analysis:
excess
are
calculations
based
on
in
excess
reagent
useful
to
is
the
solution
then
titrated
whose
with
a
concentration
standard
we
wish
to
nd.
solution.
Back
titrations
The
when:

the
reaction
is

the
substance

one

the
very
slow
titrations.
of
the
end
1
The
2
A
point
of
is
volatile,
insoluble
e.g.
is
solid,
e.g.
calcium
carbonate
ammonia
difcult
to
a
observe.
back titration
unknown
whose
concentration
amount
out
to
(in
nd
is
moles)
the
reacted
is
with
an
excess
of
known.
amount
of
added
reagent
which
is
excess.
The
number
sample of
of
moles
from
the
Put
a
of
excess
number
mass of
Add
small
sample
Shake
reagent
moles
calcium
calculated
of
reagent
from
added
carbonate
the
titration
is
originally.
present
in
a
of
marble
of
Use
the
in
a
titration
flask.
–3
50 cm
excess).
of
marble
3

an
titration
carried
Determining the

is
unknown from
of
reagent
subtracted

is
the
an
substance
titration
in
titrated
procedure
another
3
be
reactants
Calculating
General
to
a
0.25 mol dm
volumetric
contents
of
hydrochloric
pipette
the
flask
for
acid
to
the
marble
(an
this.
until
all
the
calcium
carbonate
has
reacted.
2HCl(aq)
+
(s)
CaCO
→
CaCl
3

Add
more
reaction

Titrate
hydrochloric
is
the
solution
not
(aq)
+
CO
2
acid
of
known
(g)
+
H
2
O(l)
2
concentration
and
volume
if
the
complete.
excess
using
a
hydrochloric
suitable
Worked
example
A
of
acid
acid–base
with
a
standard
sodium
hydroxide
indicator
.
1
3
sample
0.300 g
of
limestone
reacts
completely
with
50.0 cm
–3
of
3
hydrochloric
0.250 mol dm
acid
(an
excess).
It
required
35.5 cm
of
–3
Exam tips
acid.
Make
sure
that
sodium
0.200 mol dm
you
revise
mass
the
use
of:
Calculate
assuming
that
the
hydroxide
mass
this
is
the
of
to
calcium
only
neutralise
carbonate
carbonate
the
in
excess
the
hydrochloric
sample
of
limestone
present.
(g)
___________________
1
moles
=
Step
1:
Calculate
the
moles
of
NaOH
×
0.200
of
HCl
–1
molar
mass
(g mol
)
35.5
_____
mol
–3
2
concentration
(mol dm
NaOH
=
–3
=
7.10
×
10
mol
)
1000
moles
_____________
=
Step
3
volume
Take
the
account
equation.
(dm
of
2:
Calculate
the
stoichiometry
of
NaOH(aq)
moles
which
react
with
this.
+
HCl(aq)
→
NaCl(aq)
+
H
O(l)
2
–3
mol
HCl
1 mol
78
the
)
=
7.10
NaOH)
×
10
mol
(since
1 mol
of
HCl
reacts
with
Chapter
Step
3:
Calculate
the
number
of
moles
of
HCl
initially
8
added.
50.0
_____
Moles
HCl
=
×
0.250
=
0.0125 mol
1000
Step
4:
Calculate
the
number
0.0125
7.10
of
moles
of
HCl
that
reacted
with
the
CaCO
3
–3
Step
5:
-
Calculate
the
2HCl(aq)
+
×
–3
10
=
number
of
(s)
CaCO
5.40
×
10
moles
→
of
CaCl
3
mol
calcium
(aq)
+
carbonate
CO
2
(g)
+
H
2
which
react
O(l)
2
–3
5.40 ×
10
___________
–3
=
=
2.70
×
10
mol
2
(since
2 mol
of
HCl
reacts
with
1 mol
CaCO
)
3
–1
Step
6:
Calculate
the
mass
of
CaCO
(molar
mass
=
100 g mol
).
3
–3
2.70
Worked
×
×
10
example
100
=
0.270 g
2
3
A
solution
containing
–3
45.0 cm
of
0.200 mol dm
hydrochloric
acid
was
3
added
to
a
sample
20.0 cm
concentration.
The
of
aqueous
hydrochloric
acid
ammonia
was
in
of
unknown
excess.
The
excess
hydrochloric
–3
acid
was
titrated
with
aqueous
0.0500 mol dm
sodium
carbonate.
It
3
required
hydrochloric
Step
1:
of
27.5 cm
acid.
the
sodium
Calculate
Calculate
the
the
moles
carbonate
solution
concentration
of
sodium
of
to
the
neutralise
aqueous
the
ammonia.
carbonate.
27.5
_____
Moles
Na
CO
2
=
–3
×
0.050
=
1.375
×
mol
10
3
1000
Step
2:
Calculate
Na
CO
2
the
(aq)
moles
+
of
HCl
2HCl(aq)
which
→
react
2NaCl(aq)
with
+
H
3
this.
O(l)
+
CO
2
(g)
2
–3
mol
HCl
1 mol
=
2.75
CO
Na
2
Step
3:
Calculate
×
mol
10
(since
2 mol
of
HCl
reacts
with
)
3
the
number
of
moles
of
HCl
initially
added.
45.0
_____
Moles
HCl
=
–3
×
0.200
=
9.00
×
mol
10
1000
Step
4:
Calculate
the
number
of
moles
of
HCl
that
reacted
with
the
NH
3
–3
9.00
Step
5:
×
10
Calculate
–3
–
the
2.75
×
–3
10
number
of
=
6.25
moles
×
+
NH
(g)
→
NH
3
mol
of
ammonia
+
Cl
which
react.
–
+
HCl(aq)
10
(aq)
(aq)
4
–3
=
6.25
×
(since
10
1 mol
of
HCl
reacts
with
1 mol
NH
)
3
Step
6:
Calculate
the
concentration
of
the
aqueous
ammonia.
1000
_____
–3
6.25
×
×
10
–3
=
0.313 mol dm
(to
3
s.f.)
20.0
Key points

n
a
and
back
titration,
volume
is
excess
added
to
of
the
one
of
the
reagent
reagents
under
of
known
test. The
excess
concentration
reagent
is
then
titrated.

The
amount
originally

n
of
substance
added
titrations,
–
moles
calculations
consumed
substance
involve
in
a
back
titration
calculated from
use
of
the
the
=
(moles
relationship:
3
concentration
(in
mol dm
)
substance
titration).
3
=
amount
(in
mol)
÷
volume
(in
dm
)
79
8.3
Redox
titrations
Learning outcomes
ntroduction
Redox
On
completion
of
this
section,
titrations
reducing
should

be
able
reagents.
the
basic
principles
calculate
is
the
concentrations
carried
out
in
a
of
similar
oxidising
manner
or
to
acid–base
titrations.

the
The
indicator
used
can
be:
one
of
reactants
which
acts
as
an
indicator
because
it
exhibits
a
titrations
perform
calculations
based
colour
when
the
reaction
is
complete
and
it
is
in
excess
on

redox
to
titration
of
particular

used
The
to:
understand
redox
are
you
an
added
redox
indicator
which
changes
colour
when
the
reaction
is
titrations
complete.

describe
the
titration
in
use
the
of
a
redox
analysis
of
iron
tablets.
Potassium
Potassium
manganate(VII)
manganate( vii)
is
a
good
as
a
redox
oxidising
indicator
agent.
It
can
therefore
be
2+
used
to
O
H
2
calculate
(hydrogen
the
concentration
peroxide)
or
of
reducing
ethanedioic
acid
agents
(oxalic
such
as
ions,
Fe
acid).
2
burette
In
acidic
in
potassium
solution,
iron( ii)
ions
react
with
the
manganate( vii)
ions,
MnO
,
4
potassium
manganate( vii)
according
to
the
equation:
manganate ()
solution
2+
5Fe
–
(aq)
+
MnO
+
(aq)
+ 8H
3+
(aq) → 5Fe
2+
(aq)
+
Mn
(aq)
+
4H
4
pale
green
Figure
In
acidified
solution
of

deep
8.3.1
this
shows
O(l)
2
purple
the
yellow
apparatus
used
for
very
this
redox
pale
pink
titration.
titration:
Potassium
manganate( vii),
KMnO
,
is
added
gradually
from
the
4
iron () sulphate
burette

Figure 8.3.1
When
to
the
the
acidied
potassium
solution
of
iron(
manganate( vii)
is
ii)
sulphate
added
to
in
the
the
flask.
flask
it
loses
it
The titration of aqueous
purple
colour
.
This
is
because
the
purple
ions
MnO
are
changed
to
4
iron(II) sulphate with potassium
2+
almost
manganate(VII)

When
colourless
just
enough
2+
ions
Mn
by
potassium
reaction
with
manganate(
vii)
the
Fe
has
ions.
been
added
to
the
2+
flask
to
react
potassium
with
is
indicating
Did you know?
the
This
not
in
is
this
results
the
added,
ions,
Fe
manganate( vii)
purplish-pink.
indicator
all
end
in
the
addition
the
point
because
redox
the
of
of
solution
the
a
in
the
titration.
potassium
further
drop
flask
Note
that
manganate(
of
turning
vii)
an
is
self
reaction.
Permanganate titration:
worked
example
2+
Potassium
manganate(VII)
is
not
Iron
tablets
contain
Fe
ions
as
iron( ii)
sulphate.
One
iron
tablet
is
3
suitable
as
a
primary
dissolved
standard
in
excess
sulphuric
acid
and
made
up
to
in
100 cm
a
volumetric
3
flask.
because,
on
standing,
it
gives
A
sample
of
10.0 cm
of
this
solution
was
titrated
with
a
–3
0.001 00 mol dm
brown
precipitate
of
3
potassium
manganate( vii),
KMnO
.
It
required
22.5 cm
4
manganese(IV)
2+
of
oxide.
Hydrochloric
acid
should
Calculate
be
used
as
the
acid
in
manganate( vii)
potassium
to
react
completely
with
the
Fe
ions.
not
the
mass
of
iron( ii)
sulphate
(M
=
151.9)
in
one
iron
tablet.
permanganate
–
titrations
because
its Cl
ions
get
22.5
_____
Step
1:
Calculate
moles
of
the
KMnO
=
×
0.001 00
4
oxidised
to Cl
.
1000
2
–5
=
2.25
×
10
mol
2+
Step
2:
Calculate
(see
moles
of
Fe
using
the
stoichiometric
above).
–5
2.25
80
×
10
–4
×
5 mol
=
1.125
×
10
2+
mol
Fe
equation
Chapter
Step
3:
Calculate
the
mass
of
iron( ii)
sulphate
in
the
flask
(from
1
8
Titrations
and
gravimetric
analysis
tablet)
Exam tips
–4
1.125
×
–3
10
×
100/
10
=
1.125
×
10
mol
3
We
divided
by
10
because
n
3
10 cm
of
the
100 cm
were
taken
potassium
manganate( VII)
for
titrations,
you
are
allowed
to
read
titration.
the
burette from
the
top
of
the
–3
Mass
of
iron( ii)
sulphate
=
1.125
×
10
×
151.9
=
0.171 g
meniscus
This
is
intense
Potassium dichromate(VI) titrations
rather
because
that
bottom
you
method
titration
but
is
a
similar
redox
to
the
method
indicator
is
used
added.
for
a
potassium(
Potassium
vii)
2
O
2
,
contains
dichromate
ions,
Cr
7
O
2
For
dichromate(
time
vi),
that
example:
before
2–
(aq)
+
Cr
light
In

green
this
A
+
O
2
(aq)
+ 14H
cannot
is
see
so
the
doing
titrations
the
reading
colour
the
leave
a
burette
little
of
so
on
the
side
the
above
the
meniscus
7
burette
2+
6Fe
bottom.
manganate
2–
Cr
K
the
colour
properly. When
permanganate
The
than
the
3+
(aq) → 6Fe
2Cr
(aq)
+
7H
O(l)
2
orange
just
is
3+
(aq) +
7
yellow
deep
minimised.
green
titration:
redox
indicator
such
as
sodium
diphenylaminesulphonate
is
added
2+
to
the
solution
Fe
obvious
and
in
sudden
the
flask.
colour
This
change
is
because
when
a
we
small
cannot
volume
see
of
an
orange
3+
solution

Potassium
acidied

is
When
the
to
a
green
dichromate( vi)
solution
the
end
added
colour
point
in
has
is
iron( ii)
of
the
been
solution
added
containing
gradually
sulphate
flask
in
changes
the
from
ions.
Cr
from
the
burette
to
the
flask.
greenish
to
deep
purple,
reached.
Sodium thiosulphate titrations
Sodium
thiosulphate,
Na
S
2
concentration
of
iodine
S
2Na
2
O
2
in
(aq)
O
2
,
is
useful
+
I
3
(aq)
The
determining
redox
→ Na
2
colourless
for
the
3
solution.
S
2
brown
O
4
rection
(aq)
+
is:
Key points
2NaI(aq)
6
colourless
colourless

In
this
type
another
in
of
titration,
reaction.
acidic
For
we
are
example,
often
the
determining
reduction
of
the
iodine
iodate
ions
released
by
iodide
by
titrations
agents
ions
such
–
–
(aq)
+
5I
(aq)
+
6H+
→
3I
(aq)
+
3H
2
of
of
determining
the
the
oxidising
or
sodium

O(l)
n
many
redox
iodine
liberated
amount
of
in
such
oxidising
reactions
agent,
titrations
an
2
indicator
titration
involve
potassium
thiosulphate.
3
The
as
manganate(VII)
solution:
IO
Redox
such
gives
as
us
,
IO
a
method
present
in
one
a
of
indicator
3
is
the
not
added
reactants
by
giving
a
because
acts
as
an
specic
solution.
colour
In
sodium
thiosulphate
titrations:

The
colour
where

Sodium
thiosulphate
is
added
gradually
from
the
burette
to
solution
of
iodine
in
the
When
drops
the
of
starch

When
react
iodine
starch.
sharpens
just
with
in
This
the
enough
all
the
the
flask
has
produces
end
intense
very
pale
yellow,
blue–black
add
colour
.
a
involved

The
addition
has
of
a
been
further
added
drop
to
of
the
flask
need
in
the
disappearance
of
the
titrations
is from
blue
colour
.
A
or
purple
colourless
to
to
purple.
titrations
to
an
involving
dichromate(VI)
added
redox
usually
indicator.
thiosulphate

results
Redox
potassium
thiosulphate
the
in
manganate(VII)
few
point.
sodium
iodine,
change
flask.
become
an
excess.
potassium
colourless

in
the
is
(acidied)
when
colourless
solution
The
amount
of
iron
in
iron
is
tablets
can
be
determined
by
a
formed.
redox
titration
with
potassium
manganate(VII).
81
8.4
Some
uses
Learning outcomes
of
ntroduction
In
On
completion
of
this
titrations
section,
Section
8.3,
determine
should
be
able
the
describe
analysis
examples
in
the
substances
cleaners,
aspirin,
saw
mass
how
potassium
iron( ii)
of
manganate(
sulphate
present
in
vii)
can
iron
be
used
tablets.
to
Many
to:
household

we
you
of
titrimetric
quantication
(vinegar,
vitamin C
of
household
Others,
are
products
such
alkaline.
acid
or
as
or
medicines
indigestion
Titrimetric
alkali
present
in
such
(antacid)
analysis
these
can
as
vinegar
tablets
be
and
used
to
and
aspirin
some
are
acidic.
household
determine
the
cleaners
amount
of
substances.
tablets,
antacids).
Determining the
The
acid
vinegar
present
can
hydroxide
indicator
strong
be
of
as
base
titration
in
vinegar
found
known
by
value,
is
mainly
titration
acid
Unit
the
content of vinegar
of
1
is
a
vinegar
is
sample
acid.
of
The
vinegar
Phenolphthalein
weak
Study
ethanoic
a
concentration.
ethanoic
(see
acid
acid
Guide ,
and
Section
usually
is
sodium
9.6).
diluted
by
a
total
with
used
acid
as
an
hydroxide
T
o
get
factor
a
of
in
sodium
is
a
suitable
two.
Did you know?
Good quality vinegar
from
a
contains
great variety of
by fermentation. The
convert
acid
ethanol to
Analysis of
Aspirin
can
Hydrolysis
heated
CH
COOC
Back

H
a
acid
used
by volume. inegar
may
rice,
sugar
can
cane,
in the fermentation
acid. Although
acids
to
two
neutralisation
sodium
acids,
happen
be
ethanoic
present
salicylic
at
in
acid
small
be
made
palm,
etc.)
process
is the
main
amounts.
the
acid
same
and
time
COONa + HOC
3
can
be
used
ethanoic
if
the
acid.
aspirin
is
hydroxide.
COOH + 2NaOH → CH
procedure
to
quantify
H
6
the
amount
of
COONa + H
4
acid
mass
hydroxide
of
of
aspirin
known
tablets
in
a
flask
concentration
and
and
present.
boil
with
volume
excess
for
10 minutes.

Cool
the
mixture
and
titrate
the
excess
sodium
hydroxide
with
–3
H
0.05 mol dm
SO
2

The
‘acid
–
Analysis of
Many
antacid
magnesium

crushing
known
mol
of
the
NaOH
red
or
phenolphthalein
indicator
.
acid
from
is
found
by:
mol
NaOH
used
in
the
titration.
antacid tablets
tablets
contain
hydroxide
the
tablet,
then
(aq)
2
magnesium
present
concentration
Mg(OH)
82
phenol
4
content’
hydrolysis
using
be
reacting
and
+
can
hydroxide.
found
it
with
The
amount
hydrochloric
volume:
2HCl(aq)
→
of
by:
excess
MgCl
(aq)
2
+
2H
O(l)
2
O
2
is:
known
sodium
plant
4
titration
Put
bacteria
(ethanoic)
natural
5%
(apples, other fruits,
acid
hydrolysed
excess
6
least
aspirin
and
with
3
The
be
sources
acetic
acetic
in vinegar, other
at
acid
of
Chapter

back
titrating
methyl

the
amount
added
to
of
the
Analysis of
Sodium
excess
Many
bleaches
sodium
excess
acid
magnesium
tablet
–
mol
in
contain
liberated
adding
using
is
can
be
found
from:
mol
HCl
titration
chlorate(
After
potassium
SO
i),
suitable
NaOCl.
This
dilution,
the
is
commonly
bleach
is
treated
iodide.
(aq) → I
4
then
starch
from
(aq) + NaCl(aq) + K
2
titrated
indicator
as
SO
2
with
the
standard
colour
of
sodium
the
(aq) + H
4
O(l)
2
thiosulphate
iodine
Exam tips
fades.
peroxide
in
household
cleaners
do
household
cleaners
contain
hydrogen
peroxide.
Hydrogen

be
determined
titration
with
(aq)
+
acidied
potassium
by
6H
(aq)
+
5H
O
2
adding
titrating
excess
the
manganate(
vii)
potassium
iodine
(aq)
2Mn
(aq)
+
8H
O(l)
+
5O
2
iodide
liberated
→
2
with
under
acidic
sodium
–
2I
know
vitamin C,
the
DCPP
indicators. You
or
should
aware,
however,
indicators
have
one
reduced
in
the
two
that
redox
colour forms,
state
and
one
in
2+
4

of
redox
to
by:
+
2MnO
have
peroxide
be
can
not
structure
other
Some
analysis
screened
You
Hydrogen
gravimetric
cleaners
sodium
hypochlorite.
acidied
iodine
hydroxide
and
bleach
2
solution,
sodium
hydroxide
HCl
household
NaOCl(aq) + 2KI(aq) + H
The
with
Titrations
indicator
chlorate(I)
called
with
the
orange
8
(g)
the
oxidised
state.
2
conditions
and
thiosulphate.
+
(aq)
+
H
O
2
(aq)
+
2H
(aq)
→
I
2
(aq)
+
2H
2
O(l)
2
Determining vitamin C
Vitamin
such
as
C
(ascorbic
oranges
determined
(DCPIP).
colourless
addition
reduces
using
This
in
of
acid)
and
a
redox
indicator
its
is
reduced
vitamin
found
lemons.
C,
It
is
in
a
indicator
is
blue
form,
in
or
DCPIP
many
good
called
colour
pink
goes
if
fruits,
reducing
especially
agent.
It
citrus
can
fruits
be
2,6-dichlorophenolindophenol
in
its
the
oxidised
conditions
colourless
(or
pink)
form.
are
as
It
is
acidic.
the
On
vitamin
C
it.
Key points
H
H
H
C
C
C
O

O
C
O
The
acid
in
vinegar
determined
C
OH
C
H
sodium

The
be
titration
with
hydroxide.
of
tablets
salicylic
can
be
acid
in
determined
The structure of vitamin C (ascorbic acid)
using
The
by
amount
aspirin
Figure 8.4.1
can
H
vitamin
C
content
of
fruit
juice
can
be
determined
in
the
a
back
titration.
following

A
back
titration
can
be
used
way:
to

Pipette
a
known
volume
of
fruit
juice
(suitably
diluted)
into
a
determine
the
amount
of
titration
magnesium
hydroxide
present
in
flask.
antacid

Add
1%
DCPIP
solution
from
a
burette,
drop
by
drop
to
the
vitamin
C

solution
and
shake
the
flask
The
The
end
point
is
when
the
amount
blue
colour
of
the
nal
drop
of
DCPIP
household
fade
when
added
to
the
using
titration
value
can
be
compared
with
the
values
obtained
by
known
concentration
of
pure
a
be
sodium
vitamin
C
with
the
same
titration.
titrating

a
chlorine
can
solution.
thiosulphate
The
available
cleaners
does
determined
not
of
gently.
in

tablets.
solution
itamin C
can
be
determined
of
using
a
redox
indicator.
DCPIP
.
83
8.5
Titrations
Learning outcomes
without
Conductimetric titrations
Some
On
completion
of
this
indicators
section,
ions
conduct
electrical
charge
better
than
others.
For
example,
the
you
+
conductivity
should
be
able
of
and
H
OH
ions
is
very
high
compared
with
that
of
Cl
to:
2–
or
ions.
SO
During
a
reaction
where
ions
are
produced
or
consumed,
4

understand
the
potentiometric,
and

principles
the
there
thermometric
conductimetric
analyse
of
results
titrations
Figure
by
in
electrical
conductimetric
conductivity.
titration
These
using
the
changes
can
apparatus
be
shown
in
8.5.1.
of
an
acid–base
titration,
the
base
is
added
in
small
measured
amounts
thermometric
from
and
changes
measured
In
potentiometric,
are
conductimetric
the
burette
to
the
acid
in
the
beaker
.
After
each
addition,
the
meter
titrations.
reading
shown
burette
is
in
taken.
Figure
T
ypical
results
for
strong
and
weak
acids
and
bases
are
8.5.2.
meter
containing
alkali
base
strong
weak
ytivitcudnoc
magnetic
acid
strong
base
magnetic
stirring
acid
base
mS(
1–
ytivitcudnoc
acid
weak
)
mS(
1–
electrode
acid
strong
)
conductivity
strong
bar
weak
acid
weak
base
stirrer
Figure 8.5.1
volume of
Apparatus for a
base
volume of
base
conductimetric titration. The
Figure 8.5.2
concentration of alkali in the burette is
Changes in electrical conductivity for titrations involving strong and weak
acids and bases; a With strong bases; b With weak bases
about 20 times the concentration of the
acid in the beaker to minimise dilution.
The
end
graph.
a
point
Y
ou
weak
Strong
can
in
these
see
acid–weak
titrations
that
base
acid–strong
you
can
is
shown
use
this
by
the
method
‘break-point’
to
nd
the
in
end
the
point
of
titration.
base:
Both
acid
and
base
are
fully
ionised.
As
the
+
titration
proceeds,
ions
OH
combine
+
H
with
H
ions:
–
(aq)
+
OH
(aq)
→
H
O(l)
2
The
is
conductivity
an
excess
Weak
fully
of
falls
OH
acid–strong
as
more
ions
base:
and
The
water
is
formed.
conductivity
acid
is
only
rises
After
the
end
point,
there
again.
partially
ionised
but
the
base
is
ionised:
–
CH
COOH(aq)
+
–
OH
(aq)
Y
CH
3
COO
(aq)
+
H
3
O(l)
2
Did you know?
+
The
Conductimetric
titrations
for
concentrations
are
conductivity
solution.
There
(when
excess)
is
is
low
a
to
break
start
in
with
the
because
conductivity
there
are
curve
few
H
because
ions
OH
in
ions
useful
in
are
better
conductors
than
COO
CH
ions.
3
determining
in
+
precipitation
reactions,
e.g. Ag
(aq)
+
Weak
base–strong
acid:
The
base
is
only
partially
ionised
but
the
acid
–
Cl
(aq)
→ AgCl(s)
fully
ionised:
+
H
(aq)
+
+
NH
(aq)
Y
3
NH
(aq)
4
+
There
is
a
break
in
the
conductivity
curve
+
excess)
are
better
conductors
than
NH
4
84
because
H
ions
(when
in
is
Chapter
8
Titrations
and
gravimetric
analysis
Potentiometric titrations
Potentiometric
potential,
as
E
titrations
the
involve
titration
measuring
proceeds.
An
a
change
example
is
in
the
electrode
titration
of
,
iron( ii)
ions
with
cerium( iv)
ions.
2+
Fe
The
used
apparatus
rather
platinum
is
than
is
4+
(aq)
+
shown
a
easily
Ce
in
3+
(aq)
Figure
hydrogen
→
Fe
8.5.3.
electrode
3+
(aq)
A
+
Ce
standard
because
the
(aq)
calomel
latter
is
electrode
bulky
and
is
the
‘poisoned’.
meter
4+
Ce
(aq)
calomel
2+
electrode
Fe
(aq)
platinum
(Pt)
electrode
magnetic
stirring
Figure 8.5.3
magnetic
bar
stirrer
Apparatus for a potentiometric titration
4+
The
solution
of
Ce
ions
is
added
in
small
measured
amounts
from
the
2+
to
reading
is
the
ions
Fe
in
the
beaker
.
After
each
addition,
the
meter
llec
burette
2+
At
the
equivalence
point
when
the
ions
Fe
E
taken.
have
equivalence
4+
completely
reacted
with
the
ions,
Ce
there
is
a
sharp
change
in
the
point
value
of
E
(Figure
Potentiometric
potassium
8.5.4).
titrations
dichromate
are
or
useful
when
potassium
coloured
manganate(
solutions
vi)
are
used
such
as
as
titrants.
4+
volume of Ce
Figure 8.5.4
added
Change in electrode
2+
potential for the titration of Fe
Thermometric titrations
ions with
4 +
Ce
Ther mometric
enthalpy
or
displacement
added
an
titrations
changes.
in
small
insulated
temperature
It
are
be
reactions,
measured
beaker
is
can
with
taken.
useful
applied
including
amounts
results
a
reaction
acid–base
the
an
After
to
the
each
exothermic
signicant
redox
reactions.
burette
stirring.
for
produces
reactions,
precipitation
from
continuous
T
ypical
when
to
A
reactions
solution
substance
addition,
and
ions
is
in
the
an
Key points
endothermic
equivalence
reaction
point
is
are
shown
shown
by
a
in
Figure
sharp
8.5.5.
break
in
Y
ou
the
will
notice
that
the
curve.

n
potentiometric,
and
the
thermometric
conductimetric
end
) C°(
) C°(
erutarepmet
erutarepmet
break
point
in
the
is
titrations,
shown
line
of
the
by
a
sharp
relevant
graph.

Conductimetric
on
the
ions
relative
present
titrations
mobility
as
the
depend
of
the
reaction
proceeds.
3
volume
added
(cm
)
3
volume
added
(cm

Potentiometric
on
Figure 8.5.5
Change in temperature during thermometric titrations a
titrations
depend
)
the
change
in
E
values
as
the
for an exothermic
reaction
proceeds.
reaction; b for an endothermic reaction
85
8.6
Gravimetric
Learning outcomes
analysis
ntroduction
Gravimetric
On
completion
of
this
section,
analysis
be
able
understand
which
the
principles
gravimetric
describe
analyses
the function
equipment
analysis
funnel,

silica
describe
is
used
in
of
the
weighing
amount
a
of
compound
one
of
the
of
known
substances
and
ovens
how
main
steps
present.
are:

preliminary

precipitation
treatment,

ltration

washing

drying

weighing

calculation
e.g.
dissolving
or
pH
adjustment
are
some
gravimetric
(suction flask,
crucibles,
determine
on
based

to
to:
The

involves
you
composition
should
(1)
suction
the
or
precipitate
ignition
of
the
precipitate
sintered-glass
the
dried
precipitate
(to
three
or
four
decimal
places)
and furnaces)
gravimetric
used to determine the
of
the
amount
of
the
element
to
be
determined.
analysis
moisture
Did you know?
content
of
soils
and
amount
of
water
in
to nd
the
hydrated
Theodore
salts.
(1914).
these
Richards
He
was
developed
techniques
to
Precipitating
a
A
suction
sintered-glass
8.6.1
base
used
flask
shows
a
the rst American
many
of
the
determine
accurate
and filtering
and
funnel
is
sintered-glass
to
win
techniques
used
a
to
(ground
of
atomic
a
Nobel
Prize for Chemistry
gravimetric
masses
of
analysis.
about
25
He
used
elements.
sample
lter
and
glass)
wash
crucible
precipitates.
and
a
Figure
suction
funnel
filter
for
ltration.
crucible
All
the
solid
container
to
suction

The
pump
pump
is
Any
transferred
of
suction
the
on
solid
water
and
the
down
is
until
(Buchner)
to
the
precipitate
crucible
remaining
stream
The
be
turned
sintered-glass

b
must
containing
a
solid
funnel
is
the
liquid
glass
transferred
no
funnel
into
washing
out
the
to
be
ltered
is
directed
into
the
rod.
to
the
remains
not
by
funnel:
used
crucible
in
in
the
using
beaker
accurate
or
a
gentle
glass
rod.
quantitative
work
filter
porcelain
paper
base
but
is
useful
for
ltering
salts
which
have
been
puried
by
crystallisation.
with
holes
Washing
Figure 8.6.1
a
sample
Two pieces of apparatus for
filtration; a A sintered-glass crucible; b A
suction funnel (Buchner funnel)
When
washing
a
precipitate
care
must
be
taken
to
prevent
any
redissolving.

The

Small

W
ashing
in
precipitate
the
amounts
with
a
is
of
(see
water
makes
Unit
1
for
or
solution
precipitate
redissolve
washed
no
other
longer
solvent
containing
it
less
Study
than
an
likely
Guide ,
are
ion
that
necessary.
used.
which
any
Section
is
common
precipitate
to
one
will
8.7).
Drying
The
precipitate
necessary
separate
of
86
so
in
that
the
the
container
.
crucible
+
ppt
–
porous
sintered-glass
precipitate
The
mass
mass
of
of
does
not
precipitate
crucible
crucible
have
alone).
can
to
be
then
can
be
oven-dried
transferred
be
found
to
if
a
from
(mass
Chapter

Surface
at
All

When
water
heat

a
is
or
that
mass
Compounds
day
A
in
a
place
be
salts,
used
since
method
nd
the
is
free
a
precipitate
by
drying
for
1–2 hrs
some
of
the
are
of
higher
high
to
be
air-dried.
temperature
temperature
is
carried
in
out
decomposed
The
phosphorus(
solids
of
to
damp
v)
crystallisation
in
a
in
an
furnace
oven.
to
red
several
times
until
by
heating,
solid
is
left
e.g.
to
dry
for
a
the
may
be
be
soda
lime
hydrated
lost.
moisture
content
(s)
+
nH
2
mass
(m
or
for
of
of
soils
and
chloride
BaCl
2
crucible
gel
used
salts.
barium
O(s) →
silica
not
heating
hydrated
mass
empty
oxide,
should
determine
water
nH
but
mass on
used
of
2
clean
a
precipitate
crystallisation of
a
a
at
dust.
water
be
at
likely
be
many
original
Weigh
heated
loss of
can
heated
obtained.
dry
BaCl

from
‘ignited’.
containing
amount
Water of
is
should
to
Finding the
to
when
is
which
salts
desiccator
can
it
‘ignition’
constant
This
removed
removed
say
hydrated

be
precipitate
we
Drying
a
can
110 °C.


water
8
O(g)
2
residue
mass
lost
).
1

Half
ll
the
empty
crucible
with
BaCl
nH
2

Heat
gently

Let

Reheat
the
at
rst
crucible
as
then
cool
many
more
strongly
completely
times
as
then
necessary
O
and
reweigh
(m
2
to
).
2
red
heat.
reweigh.
until
constant
mass
is
obtained
).
(m
3
The
loss
in
mass
(m
–
m
2
to
calculate
nH
BaCl
2
the
O.
For
the
is
process
heated
prevent
loss
of
and
the
residual
mass
(m
–
m
3
moles
calculation
of
water
see
of
Section
)
can
be
used
1
crystallisation
per
mole
of
8.7.
2
Determining the
The
)
3
number
of
at
is
similar
about
organic
water
.
moisture
to
110 °C
material
The
that
to
content of
above.
An
constant
from
percentage
being
(%)
of
soils
accurately-weighed
mass.
burnt.
water
A
low
The
by
sample
temperature
loss
mass
of
in
mass
the
is
soil
is
due
can
of
soil
used
to
to
the
then
be
calculated.
Exam tips
Key points
f

Gravimetric
analysis
involves
weighing
a
compound
of
known
asked
about
substance
to
determine
the
amount
of
one
of
the
substances
The
main
drying

Loss
with

and
of
a
Drying
steps
in
analysis
are
to
need
dry
to
a
know
precipitation, ltration,
the
substance:
washing,
1
decomposes
2
reacts
readily
weighing.
material
common
of
gravimetric
you
present.
whether

how
composition
in
precipitates
is
reduced
by
using
a
wash
material
in
ion.
material
decomposition.
washing
should
be
carried
out
to
a
constant
weight
and
without
3
a
with
readily
or
any
drying
agent
used
dessicator
gains
readily
water from
loses
water
to
the
the
air
air.
87
8.7
Gravimetric
Learning outcomes
analysis
Determining the
hydrated
On
completion
should
be
able
of
this
section,
perform
to:
In
calculations
based
the
last
moles
obtained from
moles of
water
in
a
salt
section
of
water
we
in
introduced
hydrated
an
experiment
barium
chloride.
to
By
calculate
weighing
the
a
number
sample
of
on
barium
data
number of
you
of

(2)
chloride
before
and
after
heating,
the
mass
of
water
lost
can
be
gravimetric
found.
analysis
nH
BaCl

give
examples
of
the
use
2
of
gravimetric
analysis
in
O(s) →
BaCl
2
original
(s)
+
nH
2
mass
mass
of
O(g)
2
residue
mass
lost
quality
control.
Worked
When
example
0.611 g
0.521 g
of
chloride.
of
hydrated
residue
are
values:
(A
1
barium
formed.
Ba
=
chloride
Deduce
137.3,
Cl
the
=
is
heated
formula
35.5,
O
to
of
constant
hydrated
mass:
barium
=16).
r
Step
1:
Calculate
the
loss
of
mass
Step
2:
Calculate
the
number
of
water:
0.611
–
0.521
=
0.090 g
0.090
______
of
moles
of
water
=
–3
=
5
×
10
mol
18
Step
3:
Calculate
the
moles
of
residue
(BaCl
)
2
0.521
______
–3
=
=
2.5
×
10
mol
208.3
Step
4:
Calculate
the
mole
ratio
of
water
to
BaCl
2
–3
BaCl
: H
2
So
formula
is
O
=
2.5
BaCl
·2H

weighing

dissolving

adding
The
be
a
:
5
×
10
=
1: 2
ratio
O.
2
Determination of
can
10
2
2
Chlorides
×
–3
determined
sample
the
nitric
of
the
sample
acid
chloride
chlorides
in
then
by:
solid
metal
chloride
water
excess
precipitates
as
silver
silver
nitrate
to
the
chloride
solution.
chloride:
–
Cl
(aq)
+
AgNO
(aq)
→
AgCl(s)
+
NO
3

collecting

washing

drying

weighing
Note:
silver
the
the
the
The
chloride
chloride
formed
with
(aq)
3
by
ltration
distilled
water
chloride
the
mass
of
experiment
chloride
is
silver
should
sensitive
to
chloride
be
formed.
carried
out
in
a
darkened
room
because
light.
Exam tips
Calculations
analysis
involving
usually
precipitation
gravimetric
depend
reactions.
Worked
example
A
sample
Make
sure
0.497 g
water
.
that
you
know
the
Excess
in
the
of
a
chloride
acidied
silver
of
a
Group
nitrate
is
I
metal,
added
to
Z,
the
is
dissolved
solution.
tests for
halides
precipitate
is
ltered
and
dried
to
constant
mass.
The
mass
of
and
silver
chloride
formed
is
0.957 g.
Deduce
which
metal
is
present
sulphates.
–1
original
chloride.
(AgCl
=
143.5 g mol
;
A
chlorine
r
88
in
The
precipitation
resulting
reactions
2
on
=
35.5).
in
the
Chapter
Step
1:
Calculate
the
moles
of
silver
8
Titrations
and
gravimetric
analysis
chloride:
0.957
______
–3
=
=
6.67
×
10
mol
143.5
Step
2:
Calculate
the
=
10
mass
of
Cl
ions
in
AgCl:
–3
Step
3:
6.67
Calculate
0.497
Step
4:
×
–
the
Z
the
is
a
35.5
mass
0.237
Calculate
Since
×
=
=
of
0.237 g
metal
0.260 g
moles
Group
I
of
of
in
the
metal
chloride:
Z
metal
metal,
present
1
mol
of
and
Z
so
atomic
forms
1
mol
mass:
of
chloride
ions:
ZCl(aq)
+
AgNO
(aq)
→
AgCl(s)
+
ZNO
3
(aq)
3
mass
of
Z
________________
So:
mol
Z
=
atomic
mass
of
Z
mass
of
Z
0.260
_________
atomic
mass
of
Z
___________
=
=
=
38.9
–3
moles
Potassium
Worked
Deduce
is
the
Group
example
the
formula
I
metal
Z
which
6.67
has
an
×
10
atomic
mass
of
39.
3
of
magnesium
chloride
from
the
following
information:
0.635 g
of
magnesium
chloride,
MgCl
reacts
with
excess
silver
nitrate.
x
–1
The
mass
of
chlorine
A
silver
=
chloride
35.5,
A
r
formed
magnesium
is
=
1.914 g.
(AgCl
=
143.5 g mol
;
24).
r
1.914
______
Step
1:
Moles
of
silver
chloride:
=
=
0.0133 mol
143.5
Step
2:
Mass
of
Cl
Step
3:
Mass
of
magnesium
0.635
Step
4:
Moles
–
ions
0.472
and
in
=
mole
AgCl:
in
=
the
0.0133 ×
35.5
magnesium
=
0.472 g
chloride:
0.163 g
ratio:
Key points
0.163
______
mol
Mg
–3
=
=
6.79
×
10
mol
24

–3
So
mole
ratio
=
6.79
×
10
Calculations
Mg:
1.33
×
10
gravimetric
mol Cl
to nd
which
is
1 mol
Mg:
2 mol
the
formula
is
on
analysis
molar
can
be
used
composition
of
Cl
particular
So
based
–2
mol
compounds.
MgCl
2

Calculations
gravimetric
Gravimetric
analysis
in quality
control
to
in
Gravimetric
analysis
can
be
used
determine
the
amount
of
elements
such
as
phosphorus
in
conversion
to
insoluble
determine
sulphur
dioxide
magnesium
in
ammonium
quality
to
barium
the
air
and
in
wine
or
fruit
drinks
determine
the
a
be
of
hydrated
used
water
salt.
analysis
control
to
can
be
used
determine
%
water
in
soil
and
in foods
(by
to
determine
the
amount
of
sulphate)
particular

of
can
number
phosphate)
and
conversion
mole
Gravimetric
the

the
fertilisers
in
(by
one
on
to:


calculate
based
analysis
chloride
ions
present
in
our
water
supply
elements
in
soil
and
(by
foodstuffs.
conversion
to
silver
chloride).
89
9
Spectroscopic
9.
1
Electromagnetic
Learning outcomes
The
methods
radiation
electromagnetic
Electromagnetic
On
completion
of
this
section,
be
able
explain
the
nature
various
types
of
electromagnetic
of
these
types
frequencies.
of
For
and frequency
×
waves
that
have
electrical
directions,
e.g.
and
light
radiation
are
shown
in
waves.
Figure
9.1.1.
has
specic
light
waves
ranges
have
a
of
wavelengths
frequency
of
ultraviolet
14
–
10
7.5
×
10
Hz.
All
these
types
ranges of X-rays,
(UV), visible,
of
electromagnetic
8
travel

radiation
example,
14
and
of
particular
approximate wavelength
4.5
(IR)
in
radiation
and
recall the
vibrating
of
Each
electromagnetic

components
to:
The

consists
you
magnetic
should
radiation
spectrum
at
the
same
speed
in
air
,
3.0
×
radiation
–1
(or 300 000 000) m s
10
infrared
radio waves
recall that
energy
levels
in
Speed, frequency
atoms
and
wavelength
are quantized
The

recall the
relative
energies
and
speed
of
wavelength
electromagnetic
by
the
radiation
is
related
to
frequency
and
equation:
dangers of various types of
c
=
f λ
radiation
–1
where:

calculate
energy
equations
E = hν
using
and
c
is
speed
in
m s
the
f
E = hc/λ
is
frequency
(number
of
wave
crests
per
second)
in
hertz,
Hz.
–1
(1 Hz
λ
is
=
the
1 s
)
wavelength
in
m
Did you know?
Note:
About
100 years
gamma-rays
ago
sources
(γ-rays) were
emitting
put
pillows of
some
people,
mistaken
sleep.
belief that
Now we
smaller
it would
second).
often
used
for
frequency
when
electrons
are
being
the
wavelength,
The
greater
the
the
greater
frequency,
is
the
the
frequency
greater
is
the
(the
more
amount
waves
of
help
transferred.
So
gamma-rays
( γ-rays)
and
X-rays
carry
a
huge
know that these
amount
rays
is
under
energy
them
ν
considered.
per
the
symbol
under
The
the
The
of
energy.
Because
of
this
they
are
very
dangerous.
They
can
are very dangerous.
easily
penetrate
the
skin
and
damage
cells
in
the
body.
Even
ultraviolet
14
frequency
v/10
Hz
4
wavelength
5
6
7
600
500
8
λ/nm
700
400
elbisiv
5
6
10
7
10
frequency
10
8
10
9
10
10
10
3
–3
10
13
10
14
15
10
10
16
10
17
10
18
10
19
10
20
10
1
wavelength
Figure 9.1.1
10
–6
10
–9
10
λ/m
low frequency
90
12
10
v/Hz
wavelength
long
11
10
The electromagnetic spectrum
high frequency
short
wavelength
Chapter
rays
and
(UV
rays)
damage
have
to
the
enough
eyes
if
energy
we
are
to
cause
exposed
harmful
to
them
burns,
for
long
skin
9
Spectroscopic
methods
λ
cancer
enough.
a
Energy quanta
a
λ
In
Unit
have
1
Study
certain
9.1.3
shows
Guide,
xed
the
Section
values
of
1.3,
energy
.
movement
of
an
we
learnt
These
that
values
electron
electrons
are
between
called
energy
in
atoms
quanta.
levels
in
only
Figure
an
Figure 9.1.2
atom.
Wavelength (λ) and
amplitude (a). Wavelength is the distance
between any two similar points on the
a
b
n = 3
c
wave.
Did you know?
n = 2
photon
(radiation
Although X-rays
are
dangerous,
emitted)
they
are
‘see’
the
still
used
bones
in
in
small
the
‘doses’
body
to
and for
n = 1
sterilising
hospital
equipment.
electron
Figure 9.1.3
Movement of an electron between energy levels; a Atom in the ground
state; b Excited electron; c Electron falling back to ground state
Did you know?

When
a
quantum
of
energy
is
absorbed
by
an
electron
in
the
ground
In
state
atom
the
electron
is
excited
to
a
higher
energy
1906
light

When
an
electron
falls
back
to
the
ground
state
Einstein
again,
it
gives
out
was
of
energy
as
radiation.
We
can
also
think
of
this
energy
packets
as
In
called
a
The
energy
difference
involved
is
given
by
the
is
we
energy
that
the
related
can
and
called
Broglie
energy
of
a
=
Planck
of
its
mass.
electrons
Nowadays
as
of
waves
as
having
well
as
of
hν
(Hz)
constant
–34
(6.63 × 10
of
the frequency
particles.
radiation
speed
to
( J)
frequency
∆E
to
regard
properties
–1
J
Hz
)
light
Key points
c
____________
frequency
de
equation:
radiation
Since:
energy
Louis
photon.
photon

of
1925
a
suggested
particle
that
a
photons.
quantum
suggested
level.
__
=
or
ν
=
wavelength
λ

Electromagnetic
radiation
can
hc
___
we
can
also
write:
ΔE
be
=
regarded
as
waves
that
have
λ
a
We
of
a
can
use
this
particular
excited
limit,
atom.
we
can
equation
to
wavelength
If
the
calculate
or
frequency
calculate
the
the
frequency
of
is
energy
radiation
ionisation
emitted
emitted
is
from
measured
energy
of
the
when
a
radiation
the
(see

Speed

The
= frequency
Guide ,
Sections
1.3
and
× wavelength.
convergence
Unit
spectrum
of
electromagnetic
1
radiation
Study
and
previously
at
atom
characteristic frequency
wavelength.
ranges from
radio
1.4).
7
waves
(10
Hz)
to
gamma-rays
19
Worked
example
Calculate
the
(10

energy
of
an
electron
transition
which
emits
radiation
Hz).
Light
waves
have
a frequency
14
frequency
1.01
×
4.5
Hz.
10

–34
Planck
constant
=
6.63
×
10
×
10
Energy
into
the
equation
ΔE
=
10
12
×
1.01
we
×
10
are
the
asked
for
Avogadro
the
value
number
,
6.70
×
10
J

The
energy
per
6.02
mole
×
of
electrons,
we
multiply
the
–22
×
10
23
×
6.02
Hz.
atoms
×
10
they
can
are
only
have
23
=
values.
6.02
×
10
is
associated
given
by
with
E = hν,
a
where
value
c
10
is
the
Planck
6.70
10
–22
=
23
by
–
energy
photon
If
in
×
hν
–34
×
7
.5
levels
certain
6.63
14
–
J s.
quantized
Substituting
of
of
12
speed
of
light
and
h
is
constant.
–1
=
403 J mol
91
9.2
Beer–Lambert’s
Learning outcomes
Introduction
In
On
completion
of
this
section,


be
state
use
able
Beer-Lambert’s
given
used
1
Study
to
the
law
law
in
The
absorbed
by
to
of
a
measures
explain
visible

the
origin
and UV
explain
absorb
why
of
the
in
absorption
and
the UV
others
describe
the
samples
by
steps
visible
understand
chosen
solution.
A
and
13.3
of
the
UV
and
spectrometer
select
a
calibration
concentration
in
to
(Section
Beer–Lambert’s
molecules
and
we
saw
coloured
how
a
colorimeter
molecules
7.3).
of
A
depend
curve
wavelengths
for
a
or
ions
Both
that
particular
in
using
a
a
and
spectrometer
narrow
colorimeter
Beer–Lambert’s
are
lter
absorption
substances
regions.
on
of
UV-visible
specic
visible
band
range
of
and
law.
do
in
the
refers
to
light
passing
through
a
solution.
Absorbance
not
analysing
spectroscopy
use
law
visible
of
to
light
solution
passes
is

7.1
concentration
in
refers

is
needed
T
ransmittance
regions
Sections
the
spectroscopy
some
light
is
wavelengths
solution
lter
the
colorimeter
concentration
species
solution.
UV-visible

Guide ,
determine
to:
Beer–Lambert’s
calculate
Unit
you
is
should
law
0%.
the
absorbed
by
absorbance
through
a
a
is
solution,
Absorbance
( A)
is
solution.
0%
and
the
If
the
all
the
to
passes
transmittance
absorbance
related
light
is
100%
transmittance
and
( T)
through
100%.
the
by
If
no
a
light
transmittance
the
equation:
visible
spectroscopy
A
=
–
T
log
10

understand
the
use
of
Beer–Lambert’s
complexing
coloured
and
reagents
compounds
detection
law
states
that:
to form
(sensitivity

limits).

the
amount
the
solution
the
amount
through
In
of
light
absorbed
is
proportional
to
the
concentration
of
light
absorbed
is
proportional
to
the
distance
the
solution
(the
path
length,
it
of
travels
l).
symbols:
Did you know?
proportionality
Beer–Lambert’s
law
is
a
combination
concentration
=
absorbance
of
two
to
the
laws:
effect
Beer’s
of
the
law
which
absorbed
concentration
and
of
light
refers
by
a
to
pure
the
Lambert’s
absorbance
liquid.
solution
light
light
travels
law
through
which
ε lc
refers
distance
on
constant
solution
of
The
constant,
absorbance,
ε,
A,
is
called
when
the
the
molar
light
travels
–3
without
The
–1
.
1 mol dm
absorptivity.
It
has
units
of
for
3
mol
1 cm
It
gives
through
a
a
value
of
solution
the
of
–1
dm
cm
but
is
commonly
quoted
units.
absorbance
is
also
given
by
the
relationship:
I
o
log
∝
c
I

I
is
intensity
of
light
transmitted
through
a
colorimeter
cell
o
containing

I
is
the
the
If
the
pure
intensity
solution
meter
intensity
solvent.
of
under
readings
on
the
the
light
transmitted
through
the
cell
containing
test.
on
the
detector
,
transmittance
colorimenter
are
proportional
to
the
light
then:
in
cell
with
pure
solvent
_________________________________________
=
log
transmittance
We
92
can
use
in
cell
Beer–Lambert’s
containing
law
to
do
test
simple
constant
solution
calculations:
×
c
Chapter
Worked
example
9
Spectroscopic
methods
1
Exam tips
When
radiation
cell
1.5 cm
of
0.65.
wavelength
path
Solution
concentration

of
Rearrange
X
length,
has
of
a
the
its
200 nm
is
absorption
molar
passed
through
measured
absorptivity
of
80.
on
a
solution
X
in
spectrometer
Calculate
a
Beer–Lambert’s
is
the
complicated
solution.
have
Beer–Lambert’s
law
in
to
law
at rst
remember
the
absorbance
the
concentration
A
the
absorbance
εl
path
the
form
A
=
εlc
so
that
c
is
is
may
seem
sight
but
quite
all
you
is:
proportional
to
the
of
solution
and
subject:
__
c

Substitute
the
is
proportional
to
the
=
length
of
the
cell.
values:
0.65
_________
c
=
80
Worked
–3
=
example
×
5.4
×
10
–3
mol dm
1.5
2
–3
A
solution
containing
0.025 mol dm
copper( ii)
sulphate
(solution
A)
is
a
placed
in
placed
0.18.
is
in
spectrometer
0.48.
the
Another
same
Calculate
absorptivity
(i)
cell
the
of
path
solution
under
the
length
of
1 cm.
copper
same
concentration
copper( ii)
of
cell
The
sulphate
conditions.
of
solution
B
absorbance
(solution
The
(ii)
B)
of
is
absorbance
the
this
ecnabrosba
solution
a
is
molar
sulphate.
0.8
0.6
0.4
0.2
(i)
Since
absorbance
is
proportional
to
concentration
if
all
other
factors
0
0
are
0.2
0.4
0.5
constant
concentration
–3
absorbance
of
0.48
→
0.025 mol dm
copper( ii)
sulphate.
b
0.18
_____
So
absorbance
of
0.18
→
0.025
×
=
0.0094
(to
2
s.f.)
ecnabrosba
0.48
(ii)

Rearrange
Beer–Lambert’s
law
in
the
form
A
=
ε lc
so
that
ε
is
the
0.8
subject:
A
__
ε
=
lc
0.5

Substitute
the
1.0
values:
concentration
0.48
__________
ε
=
=
1
×
19.2
Figure 9.2.1
a At low concentrations a
0.025
graph of absorbance against
concentration shows proportionality. It
Deviation from
Beer–Lambert’s
follows Beer–Lambert’s law. b At higher
law
concentrations, Beer–Lambert’s law is not
The
relationship:
obeyed.
transmittance
in
cell
with
pure
solvent
_________________________________________
log
=
transmittance
is
not
obeyed
coloured
when
solutions.
in
high
The
increases.
curve
to
in
order
(see
concentrations
For
calculate
Section
containing
absorbance
concentration
accurately
cell
this
the
test
of
solutions
increases
reason
we
less
have
concentration
constant
×
c
solution
of
to
a
are
used,
rapidly
plot
as
a
especially
the
calibration
particular
solution
7.3).
Key points

Transmittance

Beer–Lambert’s
to

the
distance
law
it
Beer–Lambert’s
path

refers
At
length
high
and
to
light
states
travels
law
ε
is
can
a
passing
that
be
of
amount
the
expressed
constant
concentrations
the
through
through
of
solution. Absorbance
light
absorbed
is
refers
to
proportional
light
to
the
absorbed
by
a
solution.
concentration
of
the
solution
and
solution.
as:
(molar
solute,
a
A
=
εlc,
where
A
is
absorbance,
c
is
the
concentration
of
solution,
l
is
the
absorptivity).
Beer–Lambert’s
law
is
no
longer
obeyed.
93
9.3
Ultraviolet
Learning outcomes
The UV-visible
A
On
completion
of
this
and visible
section,
single
beam
be
able
or
understand

describe

the
the
understand
use
steps
by UV
detection
spectrometer
is
spectrometer
but
it
uses
a
similar
diffraction
to
a
grating
colorimeter
to
select
(see
Section
wavelengths
in
7.3
the
for
UV
to:

samples
absorption
you
diagram)
should
spectroscopy
of UV
in
visible
region
rather
than
a
lter
.
The
procedure
is:
spectra

Set

Place
the

Adjust

Put
wavelength
of
light
required.
analysing
pure
solvent
in
the
cell
(water
,
ethanol
or
other
organic
solvent).
spectroscopy
about
limits
sensitivity
the
meter
reading
to
0
absorbance
or
100%
transmittance.
and
the
sample
in
another
identical
cell
and
place
this
in
the
path
of
in UV
the
light.
spectroscopy


describe
the
samples
by
understand
steps
visible
the
in
spectroscopy
use

Record
the

Repeat
at

A
meter
reading
(absorbance
or
transmittance).
analysing
of
other
calibration
selected
curve
wavelengths.
using
standard
solutions
can
be
used
to
relate
the
visible
absorbance
to
the
concentration
of
the
substance
present
(see
Section
spectroscopy
7.3

understand
complexing
coloured
and
the
use
reagents
to form
compounds
detection
for
details).
of
A
(sensitivity
single
solution
organic
limits).
beam
spectrometer
(Figure
9.3.1)
molecules
but
can
it
be
used
cannot
satisfactorily.
be
The
to
identify
used
to
coloured
distinguish
wavelength
is
ions
in
between
usually
measured
in
–9
nanometres,
nm
(1 nm
=
m).
10
70
Using
complexing
reagents
ecnattimsnart
60
Some
ions
may
not
absorb
light
very
well
in
the
visible
or
UV
regions.
3+
Cr
(aq)
They
may
however
be
converted
to
more
highly
coloured
ions
by
forming
50
complex
40
13.3).
egatnecrep
more
ions
These
with
ions
sensitive
to
particular
may
the
have
ligands
better
absorption
(see
Unit
absorption
of
light.
1
Study
Guide ,1
characteristics.
They
may
also
Section
They
shift
are
the
30
wavelength
of
maximum
absorption.
For
example:
20
2+

ions
Fe
in
solution
concentrations
10
reacted
with
they
the
are
do
ligand
light
not
green
absorb
in
colour.
visible
If
present
radiation
1,10-phenanthroline,
in
ver y
however,
low
well.
a
When
deep
0
orange–red
400
450
500
550
600
650
complex
ion
is
for med.
At
the
appropriate
wavelength
700
2+
this
wavelength/nm
Figure 9.3.1
complex
ions
alone.
The
colour
absorbs
This
radiation
maximises
to
the
a
far
greater
precision
of
extent
the
than
the
Fe
measurements.
Absorption spectrum of a
2+

3+
solution containing Cr
of
dilute
copper(
ii )
sulphate
is
due
to
a
water–Cu
ion
ions
complex.
deep
blue
This
is
ver y
complex
light
and
blue
changes
in
colour.
the
Adding
wavelength
of
ammonia
makes
a
maximum
absorption.
High
High
one
resolution
for
used
is
shown
94
resolution UV-visible
the
UV
about
in
UV-visible
and
one
for
200–800 nm.
Figure
9.3.2.
spectroscopy
spectrometers
the
A
visible
have
regions.
simplied
two
The
diagram
of
separate
light
wavelength
this
sources,
range
spectrometer
is
Chapter
rotating
9
Spectroscopic
methods
disc
slit
M
detector
S
computer
and
light
chart
recorder
sources
R
M
Figure 9.3.2
A double beam UV-visible spectrophotometer. M = mirror. S = sample cell.
R = reference cell.

The
the

diffraction
UV
The
the
The
and
grating
visible
rotating
cell
solvent

or
disc
to
divides
up
containing
used
in
detector
rotates
regions
the
test
preparing
compares
converted
to
allow
the
beam
from
the
whole
range
of
so
and
that
a
it
alternates
reference
cell
between
containing
the
solution.
values
percentage
light
produced.
solution
this
the
to
be
(%)
of
the
sample
transmittance
and
then
reference
to
cells
molar
absorptivity.

Cells
and
radiation
A
typical
butanone
can
there
at
different
the
made
be
are
of
quartz
two
We
by
peaks,
can
organic
are
used
because
glass
absorbs
region.
spectrum
identied
275 nm.
types
of
ultraviolet
UV-absorption
compounds
another
lenses
in
is
one
use
shown
their
at
such
typical
a
in
Figure
wavelength
spectra
9.3.3.
absorption
to
of
Different
peaks.
190 nm
distinguish
For
and
between
compound.
4
10
ytivitprosba
Key points
3
10

Some
molecules
absorb
radiation
2
10
in
the UV
or
visible
region.
1
ralom
10
This
0
gives
rise
to
characteristic
spectra.
10

0
0
200
250
300
Visible
spectroscopy
is
limited
to
350
coloured
compounds.
wavelength/nm

Figure 9.3.3
UV
spectroscopy
for
organic
Limitations of UV-visible
UV
with
or
used
molecules
conjugated
A
is
The UV-absorption spectrum of butanone
visible
absolute
region
spectrum
certainty
spectroscopy
is
not
enough
to
carbonyl
identify
a
substance

because:
Samples
visible
The
solvents

The
polarity
used
may
absorb
UV
radiation
the
solvent
and
pH
can
or
are
analysed
spectroscopy
through
a
by UV-
by
passing
quartz
cell
signicantly.
and
of
with
bonds
compounds.
radiation

double
affect
the
UV
detecting
the
radiation
absorption
transmitted
compared
with
a
spectrum.
reference

The
temperature
and
high
electrolyte
concentration
may
interfere

with
the
The
sensitivity
The
method
is
limited
to
coloured
compounds
in UV
(in
visible
spectroscopy)
low
spectroscopy
compared
organic
compounds
with
conjugated
double
bonds
such
as
alternating
double
and
single
bonds
and
carbonyl
Complexing
UV
The
width
to
many
ions
can
to
be
increase
spectroscopy).
the

reagents
compounds
added
(in
other
methods.
alkenes

with
with
or
spectroscopic

detection
either:
are

and
spectrum.
limits

cell.
of
the
spectrometer
slit
and
other
variables
associated
sensitivity
and
detection
with
limits.
the
spectrometer
also
affect
the
spectrum.
95
9.4
More
about
Learning outcomes
ultraviolet
Which
The
On
completion
should
be
able
of
this
section,
molecules
absorption of

The
d
orbitals
degenerate.
explain
the
origin

explain
why
of UV
visible
radiation
regions
In
list
examples
in
and
of
the
the UV
others
the
use
Guide ,
spectra
quantization
tablets,
blood,
of
in
and
in
ions
an
isolated
all
have
transition
the
same
element
average
ion
are
described
as
energy.
of
ligands,
Section
the
orbitals
split
into
two
groups
(see
Unit
13.3).
not

When
d
energy
orbital
of
in
the
lower
visible
energy
region
to
a
d
is
absorbed
orbital
of
an
electron
higher
energy.
moves
Light
from
is
of
in
the
visible
region
of
the
spectrum.
the
substances
glucose
cyanide
element
and
do
absorbed
ultraviolet
in
They
presence
Study
a

in transition
molecules
1
absorb
light
radiation?
spectra

some
absorb UV/visible
you
to:

spectroscopy
urea
(iron

The
wavelength
between
in
the
of
split
the
d
light
absorbed
depends
on
the
energy
difference
levels.
water).
The
absorption of
Organic
compounds
radiation
which
in organic
absorb
radiation
compounds
in
the
ultraviolet
(or
visible)
Did you know?
regions
When
atomic
molecular
of
the
orbitals
orbitals
molecular
energy
than
the
overlap,
two

orbitals
has
lower
conjugated
exhibit
bonds
buta-1,3-diene,
are formed. One
atomic
usually
a
resonance
(alternating
structure.
double
and
the
C =O
group
examples
single
bonds)
are:
in
dienes,
e.g.
=CH—CH=CH
CH
2

T
wo
in
2
aldehydes
and
ketones,
e.g.
butanone
orbitals. This
called
has
a
a
bonding
higher
orbital. The
energy
than
the
=
O
is
other
atomic
CH
CH
3
orbitals. This
orbital
these
(*).
is
called
Both
σ
and
orbitals. There
bonding
contain
orbitals
lone
an
π
are
bonds
also
(n). These
pairs
of
CCH
2
3
antibonding
have
non-
usually
electrons.
When
UV
radiation
lower
radiation
is
used
energy
associated
to
level
with
passes
move
to
a
through
an
higher
orbitals
that
these
electron
energy
contain
in
compounds,
the
level.
pi
outer
These
( π)
energy
electron
energy
from
shell
levels
the
from
are
a
often
electrons.
σ*
a
π
b
antibonding
π
antibonding
π*
energy
n
π
(n)
bonding
non-bonding
π
oxygen
Figure 9.4.1
lone
pair
The relative energies of
different orbitals
π
When
an
electron
is
excited
by
Figure 9.4.2
bonding
The absorption of energy in the ultraviolet region moves an electron from a
lower energy level to a higher energy level. The orbitals involved are shown for a
ultraviolet
light,
the
a diene,
electron
b a ketone.
generally
moves
to
the
antibonding
orbital.
The
energy
energy
involved
levels
Movements
require
too
is
from
much
buta-1,3-diene,
ultraviolet
Butanone
result
(n
96
→
can
π*
and
π
the
σ
to
π*).
electrons
cause
pi
at
level
to
movements
(π
two
movements
)
to
in
π*,
the
the
the
n
UV
π*
→
π*
σ*
take
place
the
→
σ*
usually
For
within
( π*)
wavelengths.
in
n
levels
region.
antibonding
electrons
or
region.
or
UV
which
pi
different
of
π→
in
absorption
bonding
radiation
from
absorption
energy
cause
electron
from
different
→
to
bonding
only
are
absorb
two
moving
energy
the
range
from
in
sufcient
The
C =O
the
orbitals.
peaks
bond
Chapter
a
Spectroscopic
methods
b
1.0
1.0
ecnabrosba
ecnabrosba
0.5
0.5
0
0
180
200
220
240
260
wavelength
Figure 9.4.3
For
a
280
group
bonds,
absorption
as
of
the
moves
molecules,
e.g.
delocalisation
to
longer
2
CH
2
compounds,
mass
and
the
Their
substance
particular
wavelength.
concentration
increases,
Iron
in
iron
are
An
quantifying
this
260
280
300
320
(nm)
the
peak
two
of
or
three
maximum
example:
CH
2
=CH–CH=CH—CH=CH
2
2
258 nm
increased
delocalisation
→
can
as
use
in
be
used
readily
is
for
identify
interpreted
determining
solution
appropriate
to
by
as
the
measuring
calibration
particular
infrared
amount
the
curve
spectra
of
a
absorbance
is
usually
at
used
a
to
absorbance.
tablets:
510 nm
not
present
When
1,10-phenanthroline,
about
For
one,
=CH—CH=CH
spectra
main
to
240
spectra
visible
particular

with
217 nm
spectra
spectra.
220
butanone
2
ultraviolet
UV
alkenes
wavelengths.

Although
200
wavelength
171 nm
Use of
180
(nm)
=CH
CH
peak:
relate
300
Ultraviolet spectra of a buta-1,3-diene and b
similar
double
or
9
a
reacted
deep
complex
with
the
orange-red
absorbs
ligand
complex
radiation
ion
well,
is
so
formed.
can
be
At
used
for
iron.
Key points

Glucose
visible
in
blood:
Glucose
spectroscopy.
If
we
is
colourless
react
glucose
so
cannot
with
be
excess
quantied
by
Benedict’s

solution
(blue
in
colour)
an
insoluble
precipitate
of
copper(
i)
oxide
Organic
absorb
formed.
The
blue
solution
becomes
less
intense
in
colour
.
the
colour
intensity
of
the
blue
solution
using
radiation
a
we
concentration
glucose
with

Urea
a
can
can
oxidase
and
UV-visible
in
blood:
Ehrlich’s
be
other
the
can
The
glucose
measured
by
enzymes.
spectrometer
This
reagent.
calculate
also
be
at
a
The
by
formed
the
solution
suitable
analysed
product
concentration.
reacting
is
wavelength,
adding
zinc
absorbs
with

analysed
e.g.
sulphate
radiation
visible)
regions,
can
also
measuring
be
the
quantied
absorbance
by
at
reacting
it
with
specic
at
The
energy
or
n→
σ*
Cyanide
in
water:
CNBr
,
The
by
enzymes
cyanide
red
in
in
π*,
π→
moving
n→
levels
the UV
π*
causes
region.
Spectroscopy
in
the UV-visible
region
to
and
in
the
with
water
is
bromine
converted
water
.
On
to
is
used
dye
is
formed,
which
absorbs
of
a
determine
particular
the
substance
cyanogen
addition
in
solution
by
measuring
of
the
a
a
340 nm.
treatment
p-phenylenediamine
involved
energy
absorption
and
present
bromide,
have
435 nm.
amount

usually
structure.
electrons from
340 nm.

Urea
ultraviolet
Glucose
glucose
then
which
the
visible
resonance
spectrometer
,
in
By
(or
measuring
compounds,
is
radiation
absorbance
at
a
particular
at
wavelength.
530 nm.

Iron
the
Did you know?
can
The
cassava
contains
the
plant,
very
tubers
which
small
properly,
is
grown
amounts
you
risk
of
as
a
root
cyanide
being
very
in
ill
crop
its
in
many
tuberous
through
parts
root.
cyanide
If
of
the
you
do
poisoning.
world,
not
cook
tablets,
blood
be
reagents
resulting
and
cyanide
determined
specic
in
glucose
and
or
by
in
urea
in
water
adding
enzymes. The
species
absorb
the UV-visible
region.
radiation
97
9.5
Infrared
Learning outcomes
spectroscopy
Why do
In
On
completion
of
this
section,
be
able
covalent
molecule
absorb
such
as
infrared
methane
the
radiation?
electron
clouds
bonding
the
you
C
should
a
molecules
and
H
atoms
allow
the
nuclei
to
vibrate
in
two
ways:
stretching
and
to:
bending

explain
of
the
infrared
origin
(IR)
of
absorption
radiation

Covalent

A
molecules
molecule
same

describe
the
basic
steps
as
analysing
samples
spectroscopy
preparation

describe
the
by
(referring
of
a
natural
frequency
of
vibration.
absorbs
the
infrared
natural
(IR)
vibration
of
radiation
the
bonds
whose
in
the
frequency
molecule.
is
the
The
associated
with
the
vibrations
is
quantized
(see
Section
9.1).
IR

to
The
energy
absorbed
increases
the
amplitude
of
the
vibration
of
the
bonds.
solids)
limitations
have
involved
energy
in
bonds
by
of
IR

Absorption
of
IR
radiation
only
happens
when:
spectroscopy.

there
is
some
molecule
is
type
polar
of
charge
and
separation
hence
has
a
within
the
molecule
(the
dipole)
and
a

the
vibration
molecule
as
and
H
Unit
Cl
2
b
results
(see
do
in
1
not
a
change
Study
in
Guide ,
absorb
in
the
the
dipole
Section
moment
2.5).
infrared
So
region
of
the
molecules
but
HBr
such
will.
2
H
Exam tips
Figure 9.5.1
Vibrations in a C—H bond;
You
may nd
it
useful
to
think
of
vibrations
in
bonds
rather
like
springs
a Stretching vibration; b Bending vibration
attached
ways
by
to
a
pair
of
supplying
atoms. You
energy from
can
stretch
and
bend
these
bonds
in
several
your ngers.
H
C
Characteristics of
The
energy
masses
of
absorbed
the

Each

Different
in
type
of

C—H
The
IR
appears
types

The
of
a
result
the
IR
the
are
of
bond
vibration
of
C
infrared
absorbs
vibrations
spectrum
absorbed
a
regions
bending
as
as
an
and
bond
particular
stretching
to
atoms
H
spectrum
molecular
of
particular
spectrum,
at
vibrations
depends
on
the
strength.
radiation
in
H
higher
a
specic
bonds
e.g.
the
frequency.
give
rise
to
absorption
frequencies
than
the
absorptions
due
to
C—H
absorption
shows
series
of
the
dips
percentage
(peaks)
(%)
where
of
radiation
particular
transmitted.
bonds
have
radiation.
position
of
the
peaks
is
given
by
the
wavenumber
measured
–1
cm
frequency
in
hertz
_____________________
wavenumber
=
–1
speed
of
light
in
cm s
13
So
the
wavenumber
corresponding
to
a
13
9
98
due
vibrations.
×
10
frequency
of
10
/3
×
10
9
–1
=
3000 cm
×
10
Hz
is:
in
It
Chapter
9
Spectroscopic
methods
100
90
)%(
80
noissimsnart
70
60
50
40
30
20
10
0
4400
4000
3600
3200
2800
2400
2000
1800
1600
1400
1200
1000
800
600
400
–1
)
wavenumber (cm
Figure 9.5.2
The
The
A typical infrared spectrum. Each of the main dips represents the absorption of IR radiation by particular bonds.
infrared
simplied
Did you know?
spectrometer
structure
of
an
infrared
spectrometer
is
shown
in
Figure
9.5.3.
The
reference
more
more
cell
complex
ways
molecules
there
can
a
molecule,
are
in
vibrate.
which
In
the
a
water
there
detector
recorder
are
three
ways
in
which
molecules
C
IR
D
can
vibrate
but
in
propanone
there
source
are
diffraction
24
ways.
sample
linear
molecule
n
atoms
there
are
3n –
5
prism
cell
possible
Figure 9.5.3
a
grating
containing
or
For
ways
of
vibrating.
Simplied diagram of an infrared spectrometer. M = mirrors. C = Comb.
D = rotating disc.

A
beam
of
IR

The
radiation

The
level
of
compared

radiation
is
IR
with
part
of
The
diffraction
of
IR
the
is
passed
through
radiation
that

The
recorder

The
diffraction
or
a
graph
from
the
beam
helps
to
of
is
the
%
a
ceramic
sample
through
prism
brought
plots
the
which
grating
are
of
coming
mechanism
radiation
produced
cell
passing
the
this
rod
and
heated
reference
through
reference
to
the
cell.
1500 ºC.
cell.
sample
The
is
comb
is
comparison.
rotated
so
that
different
wavelengths
detector
.
Key points
transmission
against
wavenumber
.

grating,
prism,
mirrors
and
cells
cannot
be
made
Infrared
by
glass
because
glass
absorbs
IR
radiation.
The
cells
are
often
made
bromide
or
calcium
uoride.
These
substances
do
IR
when
is
the
absorbed
radiation
the
same
as
the
natural
not
frequency
absorb
radiation
molecules
from
is
potassium
(IR)
from
of
vibration
of
the
radiation.
molecules.
Preparing the
sample for
infrared
spectroscopy

Liquid
two
samples:
discs
Solid
of
samples:
potassium
This
sodium
for
sample
or
(mull)
analysis
sample
for
analysis
is
placed
as
a
thin
lm
in
between
for
sodium
is
then
can
be
two
main
molecules
types
are
of
vibration
bending
and
stretching.
chloride.
The
bromide
mixture
sample
The
sodium
The
analysis
chloride
crushed
to
powdered
is
nely
(which
form
and
a
powdered
do
not
disc.
placed
and
absorb
mixed
IR
two

forming
the
discs
Samples
of
solids for
spectroscopy
radiation).
Alternatively,
between
with
of
or
are
them
IR
made
into
a
by
disc
with
KBr
NaCl.
chloride.

In
an
IR
spectrometer,
radiation
Limitations of
infrared
absorbed
by
the
the
sample
spectroscopy
is

It
cannot
be
used
to
identify
substances
that
are
non-polar
.

It
cannot
be
used
to
identify
substances
that
are
electrolytes
compared
with
a
reference
sample.
or
have

ionic
There
the

It
are
some
limitations
to
components.
provides
information
about
the
types
of
groups
present,
use
of
IR
spectroscopy,
e.g.
including
molecules
such
as Cl
do
not
2
functional
groups,
but
not
always
about
the
structure
of
the
molecule
absorb
as
a
IR
radiation.
whole.
99
9.6
Analysing
Learning outcomes
infrared
The
band
Particular
On
completion
of
this
section,
spectra
region
groups
such
and fingerprint
as
C—H,
O—H
region
and
C
=
O
absorb
radiation
with
you
–1
wavenumbers
should
be
able
deduce

the
region
of
.
1300–3000 cm
Specic
peaks
indicate
to:
the

in
chemical
groups
including functional
groups from
information from
spectra
identify OH,
NH
IR
presence
region
of
of
the
homologous
these
groups
spectrum.
series
In
have
in
the
this
molecule.
region
almost
We
call
compounds
identical
spectra.
in
this
the
Peaks
the
band
same
in
the
–1
wavenumber
600–1300 cm
structure
C=O, C=C,
of
the
whole
region
molecule.
of
We
the
call
spectrum
this
the
tell
us
about
fingerprint
the
region .
This
2
region
COOH
and CONH
can
be
used
to
distinguish
between
molecules
with
same
groups from
2
functional
IR

group,
e.g.
propanone
and
butanone
(Figure
9.6.1).
spectra
give
examples
spectra
in
of
the
use
monitoring
pollutants
such
of
IR
Identifying
air
as CO
and
2
identifying
known
the
fingerprint
band
region
groups
2
When
a
specific
SO
values
table.
These
according
region
for
to
the
groups
these
are
due
types
)%(
Group
from
IR
groups.
to
of
spectra,
Some
stretching
atoms
alcohol
we
typical
match
vibrations;
surrounding
amine
the
peaks
wavenumbers
their
values
with
given
may
in
vary
them.
aldehyde/
alkene
carboxylic
noissimsnart
ketone
O—H
(dips)
are
acid O—H
N—H
C =C
C=O
Wavenumber /
3580–
3350–
1680–
1610–
2500–
3650
3500
1750
1680
3000
–1
3000
2000
cm
1000
–1
wavenumber
(cm
)
b
)%(
The
wavenumber
of
the
C =O
group
may
also
vary
according
to
its
environment:
noissimsnart
3000
2000
=
O
C
in
carboxylic
C
=
O
in
aldehyde
C
=
O
in
ester
acid
1700–1725
1720–1740
C
=
O
in
amide
1630–1700
C
=
O
in
ketone
1680–1700
1730–1750
1000
–1
wavenumber
Figure 9.6.1
(cm
Another
)
useful
Alcohols
Simplied infrared spectra
and
very
broad
Example
stretch
other
is
C—O
in
compounds
alcohols,
which
are
ethers
highly
and
esters
=
1000–1300
hydrogen-bonded
show
a
–1
of a propanone and b butanone
O  H
value
vibration
hydrogen-bonded OH
corresponds
group
in
an
to
peak
between
3230
and
3550 cm
1
a
This
alcohol
peak
C—O
corresponds
group
in
an
to
a
alcohol
100
90
)%(
80
noissimsnart
70
60
50
40
30
(CH
)
3
CHOH
2
20
propan-2-ol
10
0
4400
4000
3600
3200
2800
2400
2000
1800
1600
1400
–1
wavenumber (cm
Figure 9.6.2
100
Infrared spectrum of propan-2-ol
)
1200
1000
800
600
400
Chapter
Example
9
Spectroscopic
methods
2
100
90
)%(
80
noissimsnart
70
60
O  H
50
O
stretch
40
CH
30
3
20
C =O
ethanoic
acid
10
stretch
0
4400
4000
3600
3200
2800
2400
2000
1800
1600
1400
1200
1000
800
600
400
–1
wavenumber
Figure 9.6.3
We
can
(cm
)
Infrared spectrum of ethanoic acid
identify
a
very
wide
O—H
stretching
vibration
at
–1
.
2800–3300 cm
This
corresponds
to
a
hydrogen-bonded
O—H
group
in
–1
a
carboxylic
acid.
corresponds
Example
to
a
There
=
O
C
is
also
group
a
in
peak
a
at
about
carboxylic
which
1730 cm
acid.
3
100
)%(
90
80
noissimsnart
70
60
O
=
50
40
CH
C  O  CH
3
CH
2
3
C = O
the
two C  O
30
ethyl
ethanoate
stretch
stretches
20
4000
3500
3000
2500
2000
1500
1000
500
–1
wavenumber
Figure 9.6.4
(cm
)
Infrared spectrum of ethyl ethanoate
–1
We
can
identify
a
C
=
O
stretching
vibration
at
1750 cm
due
to
the
–1
=
O
C
group
in
an
ester
.
There
are
also
two
peaks
at
about
1050 cm
and
Key points
–1
which
1250 cm
correspond
to
the
two
C—O
groups
in
the
structure.

Infrared
Fourier
spectra
transform
pollutants
in
the
IR
air
and
air
as
groups
It
can
also
be
used
can
carbon
to
by
wavenumbers.
be
used
to
monoxide,
detect
sulphur
and
measure
dioxide

their
Typical
typical
the
air
.
measure
the
concentration
of
carbon
wavenumbers
groups
dioxide
The
method
particular
uses
the
molecules.
ngerprint
T
o
measure
region
the
of
the
IR
spectrum
concentration
of
are
–1
for
aldehydes
to
–1
and
identify
spectra
and
1680–1750 cm
in
be
infrared
for functional
ozone.
can
identied from
pollution
spectroscopy
such
Particular
ketones
and
3580–3650 cm
carbon
for
the O—H
group
in
alcohols.
monoxide:


draw
the
polluted
air
through
a
sample
A
wide
peak
in
the
chamber
–1
2800–3500 cm

a
beam
sample
(CO)
of
infrared
chamber
present).
radiation
and
Any
a
is
continuously
reference
decrease
in
chamber
intensity
passed
(with
of
the
no
through
carbon
beam
at
a
the
hydrogen
monoxide
carboxylic
is
due
to
the
presence
of
carbon
a
detector
measures
and
the
the
difference
amount
of
CO
in
IR
radiation
recorded
Infrared
spectroscopy
between
the
air
since
different
pollutants
have
absorbance
at
characteristic
particular
IR
spectra,
several
pollutants
at
the
wavenumbers,
same
in
such
carbon
monoxide
and
sulphur
this
concentration
of
with
method
dioxide
in
the
air
can
also
can
be
measure
used
two
carbon
maximum
is
pollutants
automatically
dioxide. The

or
monoxide
as
chambers
indicates
alcohols
acids.
monitoring

in
particular

wavenumber
region
bonding
measured.
time.
101
9.7
Mass
spectrometry
Learning outcomes
The
The
On
completion
of
this
section,
mass
mass
spectrometer
be
able
and
explain
mass
to
identify
be
used
organic
to
measure
compounds.
relative
Figure
atomic
9.7.1
masses
shows
a
mass
to:
spectrometer

can
you
accurately
should
spectrometer
the
basic
principles
spectrometer
of
(including
a
and
Figure
9.7.2
shows
a
block
diagram
of
the
main
stages
involved.
a
electromagnet
block

use
diagram)
mass
spectral
determine
data
relative
to
isotopic
A
+
masses
and
abundances
C
electron
B

describe
how
mass
spectra
are
beam
detector
used
to
distinguish
between
p
molecules
of
molecular
mass.
similar
relative
s
Figure 9.7.1
The
main
a
le
electromagnet
m
heated
cathode
A mass spectrometer
stages

V
aporisation

Ionisation:
are:
of
the
sample.
substance
vaporised
atoms

from
The
are
ions
in
of
electric
field
ions
accelerated
are
deected

The
ions
are
detected
a
given
and
electric
mass
the
magnetic
the
detector
.
e.g.
14,
m/z
is
an
16,
eld,
(z
is
ion
is
and
hit
Positive
by
an
ions
the
with
more
and
a
heated
knock
ions
electric
by
are
eld
cathode
out
one
or
collide
more
with
of
the
formed.
(through
a
negatively-
of
a
magnetic
eld,
By
on
less
the
eld.
If
A)
the
those
ions
usually
ratio
and
ion
of
an
is
with
increasing
mass/charge
ion,
charge
(line
C).
only
gradually
increasing
mass
(line
a
recorded.
detector
.
charge
deected
deected
(bent)
magnetic
the
208
by
and
15,
ion
ratio
+1.)
an
In
ion
lighter
doubly
a
the
particular
strength
(m/z
ratio)
Figure
than
charged,
is
if
than
this,
it
hit
9.7.1,
heavier
an
e.g.
m/z
deected
as
much.
+
Pb
A
208
ion
has
an
m/z
ratio
of
208,
so
a
2+
Pb
m/z
ratio
of
ion
has
104.
field
A
mass
each
spectrum
ion
plotted
spectrum
ions
+
of
shows
against
the
the
relative
m/z
abundance
ratio.
Figure
(relative
9.7.3
shows
amount)
the
of
mass
germanium.
of
100
recording
)%(
ecnadnuba
Figure 9.7.2
Main stages in a mass
spectrometer
80
60
evitaler
40
36.5%
27
.4%
20.5%
20
7
.8%
7
.8%
0
70
71
mass
Figure 9.7.3
102
B
this,
magnetic
detection
of
of
twice
ions
from
sample
plate).
ions
charge
electrons
the
sample.
The
represents
deflection
the
of

For
acceleration
high-energy
molecules
electrons
charged
conversion to
ions
or
72
73
/charge
74
75
76
ratio
Mass spectrum of germanium showing the % abundance of each peak
Chapter
Accurate
atomic
and
molecular
9
Spectroscopic
methods
masses
Exam tips
Relative
atomic
masses
1
Mass
spectra
element.
ratios
can
be
Different
because
used
to
isotopes
each
proton
identify
are
the
different
detected
and
at
neutron
isotopes
particular
has
a
present
in
whole-number
relative
mass
of
If
an
you
spectra
can
Step
1:
Multiply
Step
2:
Add
Step
3:
Divide
the
be
used
each
calculate
isotopic
gures
by
to
mass
relative
by
its
%
atomic
asked
Using
relative
abundances
the
can
masses:
abundances,
up
the
divide
abundance.
together
.
2
In
a
total
by
mass
height
Step
2:
1435
Step
3:
7263.2
that
the
you
have
abundance
this
number
spectrum,
gives
the
+
(27.4
1972.8
/
Figure
100
+
=
relative
the
of
to
add
then
in
the
Step
3.
peak
relative
each
isotope.
×
72)
569.4
atomic
of
the
masses from
of
the
relative
atomic
mass
of
follows:
+
+
(7.8
×
2701
73)
+
+
585
(36.5
=
×
74)
+
(7.8
×
75)
7263.2
72.632
numbers
spectrum
9.7.3,
as
mass
is
the
isotopes
mass
chlorine
weighted
mean
of
the
masses
present.
spectra
(Figure
100
singly
9.7.4)
shows
peaks
due
to
charged
ions
50
evitaler
mass
70)
+
mass
Molecular
The
×
in
calculated
ecnadnuba
(20.5
be
)%(
1:
all
than
1.
100.
information
Step
of
given
rather
example
germanium
Notice
calculate
masses
m/z
abundance
Worked
to
atomic
%
Mass
are
relative
doubly
charged
ions
singly0
35
charged
ions
of
the
to
the
37
Cl
and
Cl
isotopes.
The
35
18.5
The
are
due
spectrum
will
doubly-charged
also
show
small
2+
peaks
peaks
37
Cl
ions
small
and
caused
at
17.5
and
5
2+
by
10
15
mass
Cl
ionised
chlorine
Figure 9.7.4
20
25
/charge
30
35
40
ratio
Mass spectrum of chlorine
+
molecules,
.
Cl
There
are
3
peaks
of
these
molecular
(up to m/z = 40)
ions:
2
35
m/z
70:
m/z
74
due
to
35
Cl—
37
These
due
small
m/z
72
due
to
37
Cl—
Cl
37
Cl—
to
35
Cl
peaks
Cl
due
to
the
molecular
ions
are
called
the
molecular
ion
peaks
Did you know?
A
high-resolution
of
apparently
relative
For
the
isotopic
example,
mass
same
A
(the
SO
relative
relative
masses
and
can
molecular
help
distinguish
mass. This
is
between
because
both
mass
have
mass
of
a
relative
sulphur
spectrometer
is
can
32
molecular
and
of
mass
measure
oxygen
and
of
SO
and
is
measure
approximately
63.944,
respectively
(
16).
S
2
63.962
can
accurately.
16
to
it
molecules
2
atomic
high-resolution
very
S
2
64
spectrometer
more
accurately
2
32
O
=
15.995
and
S
=
31.972).
Key points

Mass
the

A
spectrometry
ions,
mass
of
deflecting
spectrum
isotopes
Relative

High-resolution
with
of
plotted

atomic
similar
involves
the
a
ions
sample
against
mass
mass
relative
converting
in
is
the
a
of
the
an
element
spectrometry
mean
can
atoms
and
shows
mass/charge
weighted
molecular
gaseous
magnetic eld
to
ions,
detecting
the
accelerating
the
relative
ions.
abundance
ratio.
of
the
isotopic
distinguish
masses.
between
molecules
mass.
103
9.8
Mass
spectrometry
Learning outcomes
Mass
When
On
completion
of
this
section,
spectra of
we
ionise
be
able
organic
molecules
compounds
molecular
compounds
such
as
propanone
in
a
mass
you
spectrometer
,
should
and
a
single
electron
may
be
removed
from
the
molecule.
The
to:
+
peak

use
data from
distinguish
the

same
explain
mass
spectra
between
relative
to
molecules
molecular
arising
gives
of
mass
ion
mass
patterns
give
information

nature
predict
of
the
organic
the
a
the
spectrometer
low.
to
the
This
form
the
molecule.
mass/charge
compounds,
very
called
is
For
ratio
relative
( m/z
the
ratio)
of
of
molecule
having
ion
propanone,
abundance
because
fragments
molecular
peak ,
the
58
the
(see
m/z
.
It
molecular
Figure
molecular
breaks
particular
M
up
in
ion
the
ratios.
This
is
called
fragmentation
molecules
identities
of
simple
molecules
explain
at
of
is
about

Fragmentation

The
more
mass

ionisation
mass
appear
many
usually
process
the
will
In
is
this
molecular
peak
9.8.1).
peak
how fragmentation
the
from
terms
‘base
peak’
generally
stable
the
occurs
fragment,
where
the
the
bonds
greater
is
its
are
weakest.
abundance
in
the
spectrum.
and
+
‘molecular

ion’
T
ertiary
carbocations,
e.g.
)
(CH
3
C
tend
to
be
more
stable
than
3
+
secondary
carbocations,
e.g.
CH
CH
CH
3

explain
the
signicance
of
and
the
secondary
more
3
the
+
stable
than
the
primary,
e.g.
CH
CH
3
M+1
peak
in
mass
2
spectra.
Figure
9.8.1
shows
the
mass
spectrum
of
propanone.
+
CH
CO
43
3
100
)%( ecnadnuba
80
60
+
[CH
COCH
3
]
3
molecular
ion
evitaler
40
58
+
15
CH
3
20
0
10
20
30
40
mass/charge
Figure 9.8.1
Each
ratio
50
60
(m/z)
Mass spectrum of propanone
fragment
has
a
particular
m/z
ratio.
Notice
the
large
peaks
at
15
+
and
43
m/z
ratios.
The
peak
at
15
is
due
to
a
CH
ion
3
+
(C
+
3H
=
12
+
(3
×
1)
=
15).
The
peak
at
43
is
due
to
a
CH
CO
ion
3
Exam tips
(2C
+
3H
formed
1
interpreting
for
exam
an
need
to
at
mass
this
consider
the
=
((2
×
following
12)
+
(3
×
1)
Remember
that
you
you
main
suggest
may
more
of
ion for
a
ions
have
been
O
be
than
given
These
O
CH
C
CH
+
3
+
CH
m/z
CH
ratio.
3
O
3
one
+
type
43)).
=
to
=
only
peaks.
3
able
16
way:
=
2
+
spectra
level,
the
in
O
=
When
+
+
C
CH
3
3
+
For
example
(CH
)
3
CH
and
2
The
+
CH
CH
3
CH
2
both
have
an
peak
ratio
of
relative
in
the
spectrum
of
the
which
is
fragments
given
an
is
compared
abundance
of
with
the
100%.
tallest
This
43.
called
104
abundance
m/z
2
the
base
peak.
For
propanone,
the
base
peak
is
at
m/z
43.
peak
is
Chapter
Distinguishing
Butane
and
between
methylpropane
molecules
mass
spectrometry
to
have
the
same
distinguish
molecular
between
these
mass,
58.
We
molecules.
are
shown
in
Figure
methods
can
uses
of
mass
spectrometry
are:
The

spectra
Spectroscopic
Did you know?
Two
use
9
testing
the
urine
of
athletes for
9.8.2.
the
presence
of
drugs
+
a
CH
CH
3
CH
2
CH
b
CH
2
CH
3
3
3

+
CH
CH
3
+
CH
2
CH
2
monitoring
pollutants
in
river
+
C
C
CH
3
CH
3
3
water.
+
CH
CH
3
H
H
2
100
100
43
43
)%(
)%(
ecnadnuba
ecnadnuba
50
29
evitaler
evitaler
58
15
50
58
0
0
40
20
ratio
mass/charge
( m/z)
Mass spectrum of a butane CH
CH
3
the
differences
in
the
spectra
CH
2
and b
( m/z)
methylpropane (CH
3
especially
)
3
at
m/z
CH
29:
+
In
butane
m/z
29
is
due
to
CH
CH
3
100
+
[CH
2
80
+
[C
there
is
no
m/z
29
evitaler
methylpropane
peak.
+
So
there
is
no
CH
CH
3
in
methylpropane.
to
CH
2
butane
m/z
43
is
O]
5
+
[C
+
40
[C
H
H
2
OH]
5
]
5
[M
20
+
1]
0
10
+
In
H
2
60
2
In
OH]
2
3
ecnadnuba
Notice
CH
2
ratio
)%(
Figure 9.8.2
20
60
mass/charge
due
CH
3
20
30
40
50
CH
2
2
m/z
+
In
methylpropane
m/z
43
is
due
to
CH
C
HCH
3
In
both
butane
and
methylpropane
m/z
Figure 9.8.3
3
58
is
the
molecular
ion
Mass spectrum of ethanol
peak.
Key points
The
M + 1
peak

Figure
9.8.3
shows
the
mass
spectrum
of
ethanol.
The
very
small
peak
In
a
mass
spectrometer,
1
compounds
m/z
unit
beyond
the
molecular
ion
peak
is
called
the
M+1
break
up
into
peak
fragments.
The
M+1
peak
arises
because
in
any
organic
compound
1.10%
of
the

The
mass
spectrometer
can
13
carbon
atoms
are
of
C
the
isotope.
We
can
work
out
the
number
of
be
carbon
atoms
( n)
in
a
molecule
by
using
this
used
to
identify
fact.
compounds from
abundance
100
_____
n
of
M+1
if
the
The
ion
ion
____________________________
abundance
of
molecular
ion,

M
molecular
molecular
ion
peak
has
an
abundance
of
49.3%
and
the
by
the
an
compound
abundance
of
3.8%,
the
number
of
carbon
atoms
in

The
=
7C

Mass
of
contains Cl
atoms
you
can
get
a
M + 2
peak
and
35
peak
in
the
spectrum. This
is
because Cl
has
two
isotopes
Cl
For
example
in
the
compound CH
Cl
2
37
M + 4
peak
is
due
to
37
ClCH
be
of
a
determined
molecular
ion
peak.
spectra
+
,
2
an
M + 2
peak
is
due
to

37
37
ClCH
the
can
be
between
same
used
to
compounds
molecular
mass.
a
and
35
an
its
distinguish
compound
mass
49.3
Did you know?
M + 4
can
atoms
from
organic
molecule.
_____
×
1.10
an
is
one
3.8
100
_____
If
a
molecular
compound
=
of
the
is:
n
peak
loss
M+1
electron from
has
typical
patterns.
produced
peak
their
fragmentation
×
=
1.10
So,
organic
Cl
The
M + 1
peak
can
be
used
to
Cl.
deduce
+
the
number
of
carbon
and
2
atoms
in
a
compound.
Cl
2
105
Revision
Answers to
all
revision questions
can
questions
be found on the
–34
h
=
6.63
×
10
8
J s;
c
=
3.0
×
10
accompanying CD.
–1
m s
;
4
a
i
If
a
solution
of
an
analyte
in
23
Avogadro’s
number
=
6.02
×
water
with
–4
10
concentration
examined
at
of
1.00
λ
×
mol dm
10
220 nm,
a
–3
the
is
absorbance
is
max
1
The
diagram
below
shows
some
of
the
energy
levels
found
of
a
hydrogen
to
be
1.40.
If
the
path
length
of
the
atom.
cell
is
1.0 cm,
what
is
the
molar
absorptivity
–19
n
of
J
ii
the
This
analyte
analyte
at
has
this
wavelength?
another
absorption
band
–19
n
J
at
λ
268 nm.
If
the
same
solution
is
max
examined
the
–19
n
b
J
A
at
268 nm,
absorbance
student
spectrum
is
planning
of
an
(ε
=
900),
what
will
be
reading?
to
analyte
record
which
the
has
UV
λ
=
310 nm
max
a
An
electron
moves from
energy
level
n
energy
change for
b
What
is
c
What
would
for
one
=
1,
emitting
this
be
electron),
the
of
of
total
the
the
n
=
3
to
photon. What
is
(ε
the
(each
electronic
in
path
kJ,
with
c
A
a
By
the
energy
of
an X-ray
transition
=
6
×
10
m)
with
that
of
an
What
order
the
concentration
to
obtain
maximum,
length
2.10
0.455,
is
×
of
analyte
cell
with
a
of
1.00 cm
with
a
concentration
–3
mol dm
when
a
be
absorbance
used?
an
10
if
an
should
has
measured
length. This
in
a
solution
absorbance
measured
found
0.184.
in
an
absorbance
cell
is
with
then
the
a
diluted
same
of
1.00 cm
and
manner,
the
is
photon
–11
(λ
at
in
solution
of
path
comparing
000).
–3
one
occurs?
2
24
prepared
radiation?
change,
atoms
same
=
0.512
emitted
energy
hydrogen
where
a
level
process?
the frequency
mole
energy
infrared
to
be
What
is
the
concentration
of
photon
x
the
–6
(λ
5
IR
×
10
m),
explain
why
short
longer
is
more
damaging
to
length
human
tissue
than
5
wavelengths.
A
UV-visible
the
What
is
the
energy
of
a
photon
of
red
(λ =
lamp
radiates
15 W
of
yellow
=
measurements,
the
and
concentration
from
can
be
Identify
by
applying
one
factor
Beer–Lambert ’s
that
can
cause
a
law.
deviation
590 nm).
from
What
is
the
energy
of
each
photon
How
many
photons
are
emitted from
per
second?
(1 W
=
Explain
why
the
use
law.
of
complexing
agents
the
is
–1
lamp
Beer–Lambert ’s
emitted?
b
ii
measures
substances,
light
a
i
spectrometer
speci c
680 nm)?
sodium
(λ
of
light
determined
A
absorption
absorbance
these
c
solution?
=
radiation
b
diluted
sometimes
required
in
this
form
of
)
1 J s
spectroscopy.
d
Determine
the frequency
of:
c
i
an X-ray
beam
which
has
a
wavelength
The
absorption
spectra
is
actually
due
to
the
of
presence
of
chromophores.
the
‘chromophore’?
What
is
meant
by
4.88 Å
ii
an
iii
microwaves
ultraviolet
ray
with
wavelength
of
211 nm
d
with
a
wavelength
of
term
State
two
limitations
of
UV-visible
0.211 cm
spectroscopy.
–10
(1 Å
=
–9
m;
10
1 nm
=
10
m)
e
A
solution
of
KMnO
has
an
absorbance
value
4
e
Given
that
the
difference
in
energy
between
–19
the
3p
and
3s
orbitals
the
wavelength
of
is
3.38
radiation
×
(in
J,
10
m
and
what
nm),
of
0.508,
when
of
525 nm.
be
absorbed
if
an
electron
at
a
wavelength
is
What
is
the
transmittance
of
this
that
solution?
would
measured
moves from
What
is
the
%
transmittance
of
this
the
solution?
3s
to
a
3p
orbital?
f
The
molar
absorptivity
of
KMnO
is
2240
at
this
4
3
Determine
the
absorbance
of
the following
a
a
solution
with
a
transmittance
b
a
solution
with
a
%
c
a
solution
with
molar
of
solutions:
0.314
wavelength.
If
the
measured
a
cell
in
absorbance
with
a
of
1.50 cm
the
solution
path
length,
–3
transmittance
of
42.4
of
10
what
is
the
concentration
in
mol
dm
–3
,
g
dm
–1
absorptivity
–5
concentration
of
3.25
×
mol dm
10
000
and
and
ppm?
(Molar
the
concentration
mass
KMnO
,
where
in
ppm
=
mass
3
absorbance
106
is
measured
in
a
is
158 g mol
;
4
–3
1.0 cm
cell.
volume
of
solution
(dm
)).
of
solute
(mg)
/
is
Chapter
6
Explain
each
of
the following
in
terms
of
9
electronic
a
The
molecule CH
CH
3
the UV-visible
molecule CH
CH
2
region
CH
2
The
Explain
does
not
absorb
in
i
how
in
methods
each
the
of
mass
–
revision
the following
questions
processes
spectrometer:
vaporisation
3
above
200 nm,
=CHCH=CH
2
b
Spectroscopic
occurs
transitions:
a
9
whereas
the
ii
ionisation
iii
acceleration
iv
deection
v
detection.
does.
2
molecule
H
H
C
b
C
H
has
two
region:
two
spectrum
H
absorption
UV-visible
Identify
H
peaks
λ
=
c
H
in
the
320
(ε
ways
can
be
in
Explain
the
meaning
used
the
analysis
in
which
data from
a
mass
used.
of
of
these
a
terms
mass
which
are
spectrum:
accessible
=
21)
and
i
the
m/z
ratio
ii
the
M
1
iii
the
base
max
λ
=
213
(ε
=
7080).
+
peak
max
c
λ
in
the UV
region
is
higher for
the
molecule
peak.
max
CH
=CHCH=CHCH=CH
2
than for
the
2
10
molecule CH
=CHCH=CHCH
2
a
Determine
a
Explain
why
a
molecule
such
relative
a CH
I
would
absorb
i
3
The
given
in
in
the
IR
region,
but
the
molecule
I
relative
atomic
b
not.
Explain
show
abundances
which
a
56
Fe,
isotopes
2
would
of
stronger
the
bonds C–Cl
or C–I
0.280%
would
absorption.
Briey
explain
how
a
ii
sample
is
prepared for
The
relative
of
The
IR
spectrum
is
a
plot
of
%
iii
transmittance
The
of
Fe,
5.85
and
%,
Fe
91.75
atomic
and
of
relative
Li
mass
have
of
isotopic
wavenumber.
i
Dene
the
ii
Calculate
term
the
are
‘wavenumber’.
wavenumber
corresponding
to
b
a

frequency
of

wavelength
2.7
×
0.082 : 1.00
atomic
mass
8.
18
×
10
a
How
could
between
IR
the
spectroscopy
isomers
in
i
mass
0.
10
CH
CH
3
ii
b
and CH
be
and
bands
the
in
and
positions
the
IR
relative
where
used
in
H
H
C
C
H
H
the
of
a
peak
respectively.
of
Mg
where
the
25
26
Mg
and
Mg
respectively.
straight
chain
molecular
ion
alkane
peak
has
a
of
to
abundance
12%
of
and
the
M+1
peak
has
0.55%.
distinguish
i
How
many
ii
What
carbon
atoms
are
there
in
a
ii?
3
of
the
of
major
is
of
the
this
compound?
molecular formula for
this
compound?
absorption
iii
the following:
Write
the
structural formula for
this
compound.
Cyclohexanol
ii
where
ratio of
Mg,
of
0.
11
the
abundance
relative
hex-2-ene
spectra
and
OCH
3
cyclohexane
Predict
i
OH
2
and
spectrum
molecule
i
2.
12%
m.
a
8
abundances
0.79,
obtained
the
relative
Hz
10
–6
of
The
is
13
have
%,
Li
the
24
against
where
58
Fe
7
Li
intensities
spectroscopy.
d
each
respectively.
isotopes
IR
mass
57
Fe,
6
c
mass for
i–iii.
54
radiation
atomic
3
element
7
the
CH
2
iv
Predict four
m/z
H
values,
major fragments,
that
would
along
appear
in
with
the
their
mass
O
spectrum
C
c
H
c
The
IR
spectrum
of
this
compound.
C
Some
of
the
peaks
of
the
mass
spectrum for
the
H
of
the
compound
compound
butan-2-ol
45,
15. Suggest
29
and
responsible for
H
these
have
the
m/z
values
identity
of
of
the
74,
59,
species
peaks.
H
–7
11
An atom emits radiation of wavelength 1.5 × 10
m.
H
Calculate the energy of this radiation per mole
H
8
of atoms. c = 3.0 × 10
has
major
absorption
peaks
in
the
regions
–1
m s
.
–34
Planck constant = 6.63 × 10
3350–3500,
3000–2850
and
1600–1459.
6.02 × 10
Suggest
these
the
identity
absorptions.
of
the
(Refer
groups
J s. Avogadro number,
23
.
responsible for
to Section
9.6.)
107
10
Separation
10.
1
Introduction
Learning outcomes
techniques
to
chromatography
The theory of
chromatography
Introduction
On
completion
should
be
able
of
this
section,
you
to:
Chromatography
mixture.

explain
the
theory
on
in
chromatography
is
based
of
adsorption
a
mixture.
and
state
that
cellulose,
silica
gel
are
examples
phase
hexane
explain
paper,
the
to
is
separate
one
of
the
the
components
compounds
or
of
a
elements
two
different
works
by
phases.
dividing
We
call
the
this
components
partitioning .
of
a
W
ater
do
not
mix.
solution
of
They
iodine
form
with
two
separate
hexane,
layers.
most
of
the
When
we
iodine
goes
shake
hexane
layer
but
some
remains
in
the
aqueous
layer
.
We
say
into
that
the
substances
differences
column,
used
component
of
iodine

a
Chromatography
between
aqueous
the
stationary
technique
and
an
alumina
a
partition
and

is
chemistry,
in
mixture
terms
In
which
has
been
partitioned
between
the
two
layers
(see
Section
10.8).
between
thin-layer
and
Did you know?
gas–liquid
chromatography.
The
word
writing’.
separate
a
solute
not
chromatography
In
the
early
coloured
days
was
of
taken from
two Greek
chromatography
the
words
technique
meaning
was
only
‘colour
used
to
substances.
molecule
adsorbed
Adsorption
mobile
partition
chromatography
phase
There
e.g.
and
are
two
main
types
of
chromatography,
adsorption
chromatography
alcohol
and
partition
chromatography.
They
both
depend
on
partitioning
the
solute
components
of
a
mixture
between
two
phases,
a
stationary
phase
and
a
molecule
mobile
phase.
strongly
solid
support,
e.g. Al
O
2
(stationary
adsorbed
phase)
solute
b
3
in
The
stationar y
alumina
less
cellulose
soluble
 bres.
components
water
mobile
phase
(aluminium
of
The
the
can
be
oxide)
a
solid,
or
a
stationar y
mixture
e.g
liquid,
phase
which
silica
e.g.
tends
are
(silicon(
water
to
hold
attracted
IV )
oxide)
trapped
to
back
it.
or
between
the
The
greater
the
phase
attraction,
the
slower
is
the
movement
of
the
components
during
chromatography.
solute
The
mobile
phase
can
be
a
liquid
or
a
gas.
The
greater
the
solubility
of
a
more
cellulose
trapped
soluble
water
particular
component
in
the
mobile
phase,
the
faster
is
the
movement
of
fibres
in
(stationary
water
Figure 10.1.1
phase)
a Adsorption chromatography;
b Partition chromatography
that
component
During
phase.
chromatography.
chromatography,
The
stationary
the
during
different
phase
mobile
Adsorption
to
phase
the
mobile
components
different
and
phase
the
extents.
separation
chromatography:
in
So
moves
mixture
some
over
are
move
the
stationary
attracted
faster
to
than
the
others
in
occurs.
The
stationary
phase
is
a
solid.
Adsorption
Exam tips
is
the
As
It
is
important
that
you
process
the
mobile
the
words
‘adsorb’
the
means
surface. That’s
should
means
use
to
in
this
diffuse
substance
like
a
the
phase
bonds
moves
of
over
varying
the
solid
to
bond
word
with
(stationary
a
solid
phase)
surface.
some
are
adsorbed
more
strongly
to
the
solid
than
others
and
occurs.
at
Partition
chromatography:
particles
of
The
stationary
phase
is
phase
moves
a
liquid
surrounding
you
a
solid
support.
As
the
mobile
over
the
section. Absorb
through
sponge
stationary
phase,
stationary
phase
the
components
which
are
more
soluble
move
more
slowly
in
the
liquid
the
taking
will
be
held
back
and
than
those
that
up
are
more
soluble
in
the
mobile
phase.
This
water.
partition
108
strength
and
separation
‘absorb’. Adsorb
forming
distinguish
components
between
of
coefcient
(see
Section
10.8).
difference
depends
on
the
Chapter
Four types of
10
Separation
techniques
solvent
chromatography
(mobile
Column
phase)
chromatography
powdered
This
is
a
form
of
adsorption
chromatography.
Silica,
alumina
or
a
solid
resin
(stationary
(stationary
phase)
is
mixed
with
a
solvent
such
as
alcohol
or
phase)
water
components
(mobile
phase).
The
mixture
is
packed
into
a
column.
A
mineral
wool
or
moving down
sintered
glass
plug
at
the
bottom
of
the
column
keeps
the
stationary
column
phase
tube
in
place.
and
The
mixture
then
allowed
then
continuously
to
to
soak
be
separated
into
the
is
added
stationary
to
the
phase.
top
of
Solvent
the
(mobile
mineral
phase)
is
added
to
the
top
of
the
tube.
The
wool
solvent
plug
moves
through
Section
10.2
Thin-layer
This
is
a
a
glass
near
and
or
the
the
moves
of
plastic
the
10.2
are
column
of
A
the
more
small
to
stationary
for
into
plate.
allowed
components
a
The
move
of
the
mixture.
See
procedure.
(TLC)
paste
spot
phase,
on
the
chromatography
chromatography
.
made
plate.
bottom
up
separating
on
adsorption
phase)
solvent
Section
tube
more
chromatography
form
(stationary
the
for
of
the
plate
up
the
and
is
Silica,
spread
mixture
placed
stationary
spot
separates
thin-layer
to
in
the
alumina
in
a
a
be
thin
phase.
into
cellulose
layer
separated
solvent
chromatography
or
even
the
over
put
(mobile
As
its
is
phase)
Figure 10.1.2
A chromatography column
solvent
components.
See
procedure.
cover
Paper
chromatography
beaker
thin
This
is
a
form
of
partition
chromatography.
The
stationary
phase
is
layer of
water
silica
absorbed
onto
the
cellulose
of
the
paper
.
The
mobile
phase
is
usually
spot
organic
liquid
or
a
mixture
of
solvents.
The
apparatus
(see
Section
on
plastic
an
of
plate
10.2)
mixture
is
similar
to
stationary
partition
that
for
phase.
TLC
As
the
themselves
but
with
solvent
between
paper
moves
the
water
instead
up
the
of
a
paper
,
(stationary
thin
the
layer
of
solvent
components
phase)
and
the
(mobile
Figure 10.1.3
(mobile
phase).
See
Section
10.2
for
more
on
paper
phase)
solvent
Thin-layer chromatography
chromatography
procedure.
Gas–liquid
chromatography
(GLC)
solute
This
is
a
form
of
partition
chromatography.
The
stationary
phase
is
soluble
high-boiling
point
porous
solid
liquid,
e.g.
a
long-chain
hydrocarbon
oil
less
a
supported
on
in
oil
a
carrier
inert
unreactive
gas,
such
e.g.
as
silica
nitrogen,
or
alumina.
helium,
The
argon.
mobile
This
is
phase
called
the
is
carrier
gas.
solute
The
mixture
to
be
separated
is
injected
into
the
apparatus
(see
gas
an
more
Figure
soluble
10.2.5,
page
111).
As
the
mixture
is
carried
through
the
apparatus
by
the
in
gas,
those
substances
that
are
more
soluble
in
the
oil
will
travel
solid
slowly
and
those
that
are
less
soluble
will
travel
faster
.
See
oil
more
Section
oil
10.2
support
for
more
on
gas–liquid
chromatography
procedure.
Figure 10.1.4

In
chromatography
stationary

a
liquid
phase
or
to
mobile
separation
the
phase
The
stationary

The
mobile

Paper,
phase
phase
thin-layer,
occurs
stationary
adsorption

separate
the
moves
solutes
through
or
over
a
phase.
Chromatographic
mobile
Partition in gas–liquid
chromatography
Key points
on
a
can
can
be
column
solid
be
a
a
by
a
solute
either
is
transferred from
partition
between
a
the
gas
and
surface.
solid,
liquid
and
when
phase
or
e.g.
a
silica
or
alumina
or
a
liquid.
gas.
gas–liquid
chromatography
are
used
to
substances.
109
10.2
More
about
Learning outcomes
chromatography
Column
After
On
completion
should

be
able
this
section,
and
the
terms
‘retention
‘visualising
agent’
‘retention
Add

Allow
‘solvent

the
Keep
the
in
a
the
basic
separating
mixture
the
using
steps
mixture
the
been
to
mixture
adding
solvent
with
describe
has
packed,
the
be
to
separated
soak
into
to
understand
components
R
of
values
and
f
retention
times
quantifying
are
is:
top
of
column
the
column.
(open
the
tap
at
the
it.
solvent
drain
Don’t
(mobile
through
let
the
phase)
carrying
column
run
to
the
the
top
of
the
components
column
of
the
and
let
mixture
dry.
involved

Collect
the
chromatography
how
the
the
fractions
of
appropriate
volume
used
in
in
test
tubes
at
the
bottom
of
column.
3

procedure
bottom).
front’

column

time’,
and
the
you
to:
understand
factor’
of
chromatography
These
may
be
from
3
to
1 cm
100 cm
depending
on
the
size
of
the
column.
substances.
mixture
solvent
A
B
A
B
Figure 10.2.1
Collecting the fractions in column chromatography. The diagram shows the
separation of a mixture containing two components, A and B.
Thin-layer
The
a
chromatography
procedure

Place

Dip
paper
and
a
is
spot
the
paper
the
of
paper
same
the
(or
the
base

Allow
the
solvent

When
the
for
both
mixture
TLC
below
chromatography
to
plate)
TLC
be
and
paper
separated
into
a
on
solvent.
chromatography.
the
The
base
line.
solvent
level
must
be
line.
to
solvent
move
front
up
is
the
near
paper
the
(or
top,
TLC
mark
its
plate).
position.
base
Exam tips
M
A
B
C
line
When
carrying
out TLC
or
paper
chromatography
remember:
b
lid
1
Mark
be
the
base
line
and
chromatographed
solvent front
as
in
pencil. The
components
of
ink
will
well!
chromatography
2
solvent
Put
a
cover
over
the
tank
or
beaker. This
prevents
solvent
loss
by
paper
evaporation
front
Visualising
and
allows
agents
equilibration
and
of
the
vapour
with
the
liquid
solvent.
retention value, R
f
M
A
B
C
solvent
When
chromatography tank
the
nished
agent).
Figure 10.2.2
components
of
chromatogram
This
reacts
with
a
or
mixture
TLC
the
are
plate
not
with
colourless
a
coloured,
we
visualising
components.
A
spray
agent
the
(locating
coloured
Paper chromatography;
compound
is
formed.
The
colour
may
sometime
need
to
be
‘developed’
by
a A mixture and three pure substances, A,
warming
the
treated
paper
.
Different
types
of
visualising
agents
are
used
B, C are placed on the base line; b The
chromatogram after separation. The
mixture contains A and C.
110
for
different
give
purple
types
of
coloured
compound,
spots.
e.g.
ninhydrin
reacts
with
amino
acids
to
Chapter
We
far
can
the
identify
spots
solvent
the
have
front
has
components
moved
moved.
from
We
on
the
call
a
chromatogram
base
this
line
the
by
compared
retention
comparing
with
value ,
how
how
far
10
Separation
techniques
Did you know?
the
Paper
R
chromatography
can
also
be
f
carried
distance
from
base
line
to
centre
of
out
by
placing
the
solvent
the
apparatus.
in
spot
____________________________________
R
a
=
trough
at
the
top
of
f
distance
from
base
line
to
solvent
front
This
In
Figure
10.2.4
the
value
R
of
component
A
is
4/6
=
0.67
and
the
R
f
value
of
component
B
as
called
descending
paper
chromatography.
f
is
1.5/6
=
0.25.
solvent
Gas–liquid
chromatography, GLC
The
for

apparatus
The
mixture
through
a
substance
be
a
gas,
GLC
to
long
be
liquid
or
shown
separated
spiral
injected
of
is
tube
must

The
time
injection
is

The
components
of

The
components
leaving
is
Fig
10.2.5.
injected
containing
be
volatile
in
able
to
into
the
form
The
the
procedure
gas
stationary
a
vapour
which
is:
ows
phase.
easily,
The
e.g.
it
has
to
Figure 10.2.3
solid.
recorded.
solvent front
changes
in
thermal
the
mixture
the
separate
tube
conductivity
are
of
in
the
detected
the
gas
tube.
(usually
coming
out
by
measuring
from
A
the
6 cm
apparatus).
4 cm
B
The
separated
between
components
injection
and
leave
detection
the
is
tube
called
at
different
the
times.
retention
The
time .
We
time
1.5 cm
can
base
identify
a
retention
component
times
for
by
matching
particular
its
retention
substances
under
time
the
with
same
line
known
conditions.
Figure 10.2.4
Calculating R
values from
f
detector
a TLC plate
sample
injection
to
chart
recorder/PC
carrier
gas
Key points

variable
spiral
temperature
paper
and
thin-layer
chromatography,
containing
oven
stationary
In
tube
phase
the
components
of
identied
their
by
the
mixture
R
are
values.
f
Figure 10.2.5
Gas–liquid chromatography

The
R
value
is
the
distance
f
moved
by
a
specic
component
B
from
the
distance
base
line
moved
divided
by
the
by
the
solvent
rotceted
A
front from

A
visualising
morf langis
colourless
C
the
or
the
line.
reagent
reacts
components
thin-layer
give
base
in
a
with
paper
chromatogram
separated
to
components
colour.

2
4
6
8
retention
10
time
12
14
16
18
(minutes)
In
gas–liquid
the
components
retention
Figure 10.2.6
chromatography,
20
are
identied
by
times.
A GLC trace. Each peak represents a different component.
111
10.3
Applications
Learning outcomes
Column
This
On
completion
of
this
of
section,
be
able
method
describe
how
experiments
using
layer
paper,
to
to
carry
out
separate
column,
mixtures
and
state
thin-
chromatography
some
Each
of
of
that
amino
fairly
acids
or
large
amounts
mixtures
of
of
material
proteins.
can
be
Columns
e.g.
analysed
sizes.
plant
from
proteins
by
Larger-sized
oils
such
the
can
by
columns
limonene
bottom
be
measuring
quantitatively
as
of
the
analysed
the
be
for
column
used
with
at
can
be
purifying
drugs.
analysed
by
280 nm.
ninhydrin
for
purifying
quantitatively
absorbance
reaction
can
or
and
Amino
acids
can
measurement
of
of
colour
intensity
using
visible-spectroscopy
.
Figure
10.3.1
shows
a
methods
analysis
of
separate
amino
acids
collected
from
the
column.
analysis, forensic
of
natural
dica
purication
of
a
the
mixture
using
chromatography.
alanine
1.5
serine
valine
aspartic
1.0
×
fo noitartnecnoc
components
2.0
m d lom
quantifying
steps
3–
basic
)
the
onima
understand
involved
e.g.
collected
products)

advantage
various
products,
fraction
typical
testing,
made
automatically
,
the
(pesticide
the
mixtures
UV-spectrometry
applications
chromatographic
be
natural
be

has
e.g.
to:
can

chromatography
you
separated,
should
chromatography
0 1(
3
acid
0.5
0
0
Did you know?
50
100
3
volume
Columns for
collected
(cm
)
column
Figure 10.3.1
chromatography
can
be
as
wide
Quantifying amino acids separated during column chromatography. The
as
amino acid content in each tube was determined by colorimetry.
3.2 metres
These
can
and
be
as
high
used for
as
15 metres.
separating
and
Thin-layer
purifying
large
amounts
of
and
paper
chromatography
materials.
These
such
methods
as
amino
however
,
can
be
acids,
completely
used
plant
to
separate
pigments
separate
small
and
amounts
food
compounds
of
colourings.
with
similar
compounds
We
cannot,
values.
R
We
can
f
use
two -dimensional
After
it
the
90º
initial
and
different
chromatography
chromatography,
carry
out
solvent
we
help
allow
chromatography
(Figure
to
in
a
overcome
the
paper
different
to
this
dry
problem.
and
direction
then
using
turn
a
10.3.2).
= Origin
Leu
Leu
Glu
Glu
Asp
Asp
Run
in
the
chromatogram
solvent
Turn
the
paper
90°
Run
1
Figure 10.3.2
in
the
chromatogram
solvent
2
Two-dimensional paper chromatography of the three amino acids leucine
(Leu), glutamic acid (Glu) and aspartic acid (Asp)
The
R
values
of
coloured
materials
are
easily
calculated.
If
colourless
f
compounds
suitable
of
112
are
separated,
visualising
materials
are
to
agent.
be
the
paper
These
identied
or
TLC
methods
but
are
plate
are
less
must
useful
useful
be
when
when
sprayed
small
with
a
amounts
quantication
of
Chapter
large
amounts
made
by
solvent,
of
cutting
then
or
Gas–liquid
mass
or
sensitive
foodstuffs
often
in
required.
Quantication
removing
analysing
the
the
can,
compound
solution
in
using
however
,
the
spot
be
with
a
UV-visual
from
GLC
spectrometer
is
used
analyse
forensic
to
can
for
separate
pesticide
analysis
be
fed
directly
identication.
and
identify
concentrations
to
separate
and
into
The
traces
in
the
a
mass
method
of
can
be
substances
environment.
identify
in
It
Exam tips
is
particular
Remember
compounds,
in
samples
and
or
of
urine
times
using
of
in
similar
typical
for
ow
is
rate,
given
by
compounds
gas
determine
fuels.
A
gas
concentration
well-known
use
performance-enhancing
components
Quantifying
A
to
analysing
same
conrmation
that
medicine
athletes
the
the
techniques
spectrometry.
arising
IR
and
and
used
are
spots,
Separation
chromatography, GLC
components
spectrometer
very
the
quantitatively
spectroscopy
The
materials
out
10
are
matched
carrier
mass
have
amounts
gas
with
and
those
of
stationary
spectroscopy.
similar
is
One
retention
in
drugs.
in
testing
The
the
blood
substances
the
of
GLC
components
retention
and
Additional
limitation
the
separation
in GLC
chromatography
retention
known
phase.
that
of
blood
the
mobile
is
in
the
and
depends
on
stationary
mobility
or
paper
the
phase
solubility
in
the
phase.
times.
using GLC
chromatogram
is
shown
in
Figure
10.3.3.
hex-1-ene
rotceted
heptane
pentan-2-one
morf langis
Key points

5
10
15
Column
used
retention
time
to
purify
natural
can
be
products.
(min)

Figure 10.3.3
chromatography
20
The
amount
of
each
component
The separation of three volatile organic compounds by gas–liquid
in
column
chromatography
chromatography
can
be
calculated
analysis
If
spectroscopic
methods
are
not
available
for
quantifying
the
amount
of
by
samples
by
IR
or
of
UV-spectroscopy.
each
component,
Since
the
the
peaks
we
are
can
use
roughly
the
area
triangular
under
in
each
shape,
peak
we
as
can
a
rough
easily
guide.
calculate

area:
1
area
of
triangle
×
=
base
×
In
gas–liquid
chromatography,
components
of
be
by
identied
mixtures
their
can
retention
height
2
times.
The
computer
attached
to
the
GLC
apparatus
can
calculate
this
value

quite
easily.
We
can
also
calculate
the
percentage
(%)
composition
of
The
in
component
in
the
mixture
as
long
gas–liquid
each
peak
is
well
there

the
are
peak
peaks
area
is
for
all
the
directly
components
proportional
in
to
the
the
mixture
peak
composition
component
be found
concentration.
area
of
under
by
each
measuring
the
peak
mass
or
by
spectrometry.

Chromatography
in
%
each
separated
area

of
chromatography
as:
can

amounts
any
pesticide
can
be
used
analysis, forensic
A
________________________________________
=
of
component
A
testing
sum
of
the
peak
areas
of
all
the
and
purication
of
natural
components
products.
113
10.4
Raoult’s
Learning outcomes
law
and vapour
Vapour
Figure
On
completion
of
this
section,
be
able
pressure
10.4.1
molecules
state

interpret
a
ask
evaporate
of
water
from
from
the
Raoult’s
law
boiling
of
water
an
equilibrium
molecules
to
and
is
established,
from
the
in
liquid
O(l)
Y
H
2
curves
of
ideal
has
form
a
been
removed.
vapour
.
which
is
the
the
rate
of
movement
same.
O(g)
2
and
The
mixtures.
pressure
pressure.
pressure
partial
exerted
V
apour
exerted
vapour

vapou
Liquids
said

to
that
be
Liquids
An
We
that
the
the
each
vapour
varies
molecules
with
component
liquids
dissolve
do
not
liquids
example
say
by
miscible.
Immiscible
liquid
by
pressure
is
called
temperature.
in
the
vapour
In
the
a
vapour
mixture,
alone
is
the
called
the
pressure
Mixtures of
Figure 10.4.1
air
and
point–
H
composition
non-ideal
which
surface
to:
Eventually,

shows
you
W
ater
should
pressure
is
a
–
in
An
Raoult’s
each
dissolve
form
is
an
in
of
whatever
is
a
each
separate
mixture
mixture
other
,
example
other
if
of
are
after
and
solution
the
mixture
layers
hexane
ideal
law
volumes
ethanol
said
to
be
shaking
added,
and
are
water
.
immiscible.
them
together
.
water
.
it
obeys
Raoult’s
law :
Liquid–vapour equilibrium
The
partial
vapour
pressure
of
a
component
in
a
mixture
equals
its
mole
in a flask of water
fraction,
×
x
the
vapour
pressure
of
the
pure
component.
A,
vapour
erusserp
of
p
pressure
pure A
hexane
mole
partial
p
heptane
p
vapour
ruopav
of A
=
p°
A
×
x
A
fraction
A
of A
in
in
p
hexane
mixture
mixture
p
For
0
an
ideal
mixture
of
two
components
A
and
B,
the
total
vapour
1
pressure
mole fraction
of
is:
hexane
o
pure
pure
heptane
hexane
p
Mixtures
Figure 10.4.2
= p
T
form
ideal
+
p
A
=
solutions
o
(p
×
B
x
A
)
+
(p
A
×
x
B
)
B
if:
Vapour pressure–

the
intermolecular
forces
between
the
molecules
in
the
mixture
are
composition curve for a mixture of hexane
similar
to
those
in
the
pure
substances
and heptane

there
Figure
are
no
10.4.2
enthalpy
shows
the
or
volume
effect
of
changes
Raoult’s
on
law
mixing.
on
an
ideal
solution
(a
Did you know?
mixture
All
liquid
greater
mixtures
or
law. Those
lesser
that
deviate
to
extent from
more
or
of
law
are
mixtures. The
from
boil’
two Greek
and
called
word
‘state’.
at
a
xed
temperature.
As
the
mole
fraction

the
partial
of
the
more
volatile
component
(hexane)
increases:
Raoult’s
pressure
pressure
of
of
the
the
less
more
volatile
volatile
component
component
increases
and
the
decreases
zeotropic
comes
meaning

the
total
pressure
pressures
‘to

the
The
line
=
for
total
the
experimental
often
use
graphs.
114
heptane)
less follow
zeotropic
words
and
a
partial
Raoult’s
hexane
boiling
The
increases
so
total
pressure
measurement
points
boiling
that
at
any
point
the
sum
of
the
partial
pressure
of
point
is
of
mixtures
is
the
a
straight
vapour
to
line.
pressure
mirror
temperature
vapour
at
is
difcult.
So
we
pressure–composition
which
the
vapour
pressure
Chapter
equals
the
atmospheric
pressure.
The
molecules
of
a
more
10
Separation
techniques
volatile
98
more
mixture,
mixture
volatile
the
component
boiling
relationship
Non-ideal
escape
points
with
more
has
vary
the
a
as
mole
readily
lower
into
boiling
shown
in
fraction
of
the
vapour
point.
Figure
each
For
phase.
an
10.4.3.
So
ideal
There
is
a
69
gniliob
linear
a
tniop
the
of
) C˚(
component
component.
mixtures
mole fraction
Some
law
.
mixtures
The
do
not
deviations
relationship
obey
can
between
be
the
Raoult’s
positive
vapour
law
.
or
W
e
say
negative.
pressure
or
they
deviate
There
boiling
is
not
point
from
a
and
Raoult’s
of
hexane
pure
pure
heptane
hexane
linear
composition.
Figure 10.4.3
Boiling point–composition
curve for a mixture of hexane and heptane
Exam tips
will
not
be
expected
pressure–composition
to
do
curves
or
ethanol
and
boiling
based
on
vapour
point–composition
Raoult’s
curves.
ruopav
Positive deviations from
Example:
calculations
erusserp
a
You
law
cyclohexane.
mole fraction

The
bonding
between

The
between
ethanol
ethanol
alone
cyclohexane
and
and
cyclohexane
cyclohexane
molecules
get
in
the
is
weaker
than
ethanol
pure
pure
cyclohexane
ethanol
alone.
way
of
the
hydrogen
bonding
in
b

ethanol
The
molecules
So
the
ideal

The
to
the
in
the
There
is
mixture
net
are
bond
more
breaking.
likely
to
escape
from
the
gniliob
liquid

molecules.
tniop
the
vapour
.
vapour
pressure
of
the
mixture
is
higher
than
expected
for
an
mixture.
boiling
point
is
therefore
lower
than
expected.
mole fraction
ethanol
Negative deviations from
Example:
ethyl
ethanoate
and
Raoult’s
pure
pure
cyclohexane
ethanol
law
trichloromethane.
Figure 10.4.4

The
bonding
between
ethyl
ethanoate
and
trichloromethane
Positive deviation from
Raoult’s law. The dashes show the line
is
expected if Raoult’s law is obeyed.
stronger
than

There
net

The
between
ethyl
ethanoate
and
trichloromethane
alone.
a Vapour pressure–composition curve and
to

So
is
bond
molecules
the
the
in
forming.
the
b boiling point–composition curve.
mixture
are
less
likely
to
escape
from
the
liquid
Key points
vapour
.
vapour
pressure
of
the
mixture
is
lower
than
expected
for
ideal

Raoult’s
law
states
that
the
mixture.
partial

The
boiling
point
is
therefore
higher
than
vapour
the
b
vapour
tniop
erusserp

An
ideal
gniliob
ruopav

mixture
×
its
of
equals
the
pure
mole fraction.
obeys
Raoult’s
Boiling
point–composition
ideal
mixtures
show
a
can
linear
be
curves
drawn
relationship
mole fraction
CHCl
the
composition
and
CHCl
3
ethyl
3
pure
trichloromethane
pure
ethyl
ethanoate
pure
the
Negative deviation from Raoult’s law. The dashes show the line expected if
Raoult’s law is obeyed.
boiling
point.
trichloromethane

Figure 10.4.5
a
mixture
between
ethanoate
a
law.
which
pure
in
pressure
component
for
mole fraction
of
expected.
component
a
pressure
a Vapour pressure–composition curve and b boiling point–
Boiling
for
point–composition
non-ideal
positive
or
mixtures
negative
curves
may
show
deviations.
composition curve.
115
10.5
Principles
Learning outcomes
of
distillation
Simple distillation
When
On
completion
of
this
section,
we
boiling
should
be
able
need
point
understand
which
the
principles
distillation
distillation
separate
below
about
a
product
250 ºC
which
from
a
is
a
liquid
mixture,
we
or
solid
can
use
with
a
simple
to:
distillation.

to
you
are
on
For
compounds
boiling
above
about
180 ºC
we
use
an
air
condenser
.
and fractional
based.
thermometer
distillation
water
out
flask
condenser
mixture
water
in
distillate
heat
Figure 10.5.1
The
a
Simple distillation
mixture
lower
boiling
collected
in
of
This
the
are
time
minerals
salts
in
a
be
each
not
the
in
An
it.
in
the
components
vapours
of
the
mixture
condenser
of
the
will
and
mixture
condense
in
with
is
have
cooler
condenser
.
boiling
so
component
liquees
they
points
do
example
The
concentrated
the
their
the
the
enough
other
.
then
points,
if
of
other
reach
used
present
more
If
boiling
and
can
vapour
vaporises
different
as
The
receiver
.
ask
method
same
point
higher
the
mixture
boiled.
the
sufciently
parts
is
water
is
of
the
components
not
to
the
purication
distils
reach
off
rst,
the
of
condenser
of
sea
leaving
the
at
water
the
the
from
mineral
solution.
Fractional distillation
Simple
other
to
distillation
compounds
separate
fractional
A
column
into
used
a
longer
contact
the
of
glass
(Figure
successive
separation
within
containing
to
The
be
used
similar
if
the
boiling
narrow
distillate
points
range
of
to
is
the
boiling
found
one
to
contain
required.
points
we
In
order
use
distillation
is
through
116
liquids
surfaces
come
cannot
with
with
liquid
column
the
beads
10.5.2).
the
liquids
rods
or
the
whose
a
column
descending
vapour
and
or
The
column
allows
liquid
with
the
and
bulbous
ascending
separation
vapour
occurs
equilibria.
slower
boiling
the
heating,
points
are
the
close
better
to
one
is
the
another
.
Chapter
10
Separation
techniques
thermometer
water
out
condenser
fractionating
column
packed
water
with
glass
boiling
in
point
beads
of
pure
tniop
V
gniliob
distillate
distillation
(ethanol)
B
T
(X)
b
L
boiling
flask
point
0
X
X
1
of
pure C
mole
ethanol
pure
and
B
pure C
fraction
water
of C
heat
Figure 10.5.3
Boiling point composition
curve for a mixture of liquids B and C.
Figure 10.5.2
The
Fractional distillation
line L represents the boiling point of the
liquid. The line V represents the boiling
point of the vapour.
How does fractional distillation
T
o
see
two
(when
in
components
the
the
vapour
mixture
component,
C,
composition
of
the
pressure
is
in
of
works
X.
it.
this
The
can
mixture
=
The
we
are
external
vapour
,
vapour
distillate
refer
is
to
B
and
C.
pressure),
however
,
at
Figure
this
shown
10.5.3.
At
the
has
its
more
temperature
by
.
X
In
boiling
mole
of
is
other
point
fraction
the
of
the
volatile
shown
words,
by
the
Q.
Q
T
b
q
R
gniliob
C
distillation
tniop
The
how
work?
The
S
r
liquid
s
mole
0
1
X
X
X
1
fraction
of
C
in
the
vapour
has
X
2
1
3
increased.
mole fraction
pure
Figure
10.5.4
When
we
shows
heat
up
what
the
happens
mixture
of
as
we
continue
composition
X
to
to
distil
its
the
boiling
B
pure C
of C
mixture.
point,
T
:
Figure 10.5.4
Boiling point composition
b
curve for fractional distillation

The

At
vapour
this
gets
boiling
richer
in
the
more
,
the
vapour
point,
T
by
line
volatile
and
component,
liquid
are
in
C.
equilibrium.
b1
Key points
This

The

This

At
is
shown
vapour
the
rises
up
temperature
the
drop
qQ.
column
is
and
gets
represented
by
cooler
line
until
it
condenses.

Simple
points
r
,
where
the
boiling
point
is
lower
,
there
is
a
new
equilibrium
mole
fraction
of
C
being
is
substances
which
are far
used
with
to
boiling
apart from
with
each
the
distillation
separate
Qr
.
other,
e.g.
water from
X
1
mineral

At
this
lower
boiling
point,
T
,
the
vapour
and
liquid
are
in
a
salts.
new
b2
equilibrium.

The
This
composition
is
of
shown
this
by
new
the
line
mixture

rR.
is
X
,
which
has
an
even
Fractional
distillation
obtain
a
complete
liquids
within
is
used
to
separation
of
greater
2
mole
fraction
of
component
C.
boiling

The
process
(mole
As
the
continues
fraction
vapours
=
rise
in
this
way
until
the
vapour
consists
of
C

the
column
through
successive
equilibria,
richer
and
richer
in
the
more
volatile
component.
Fractional
distillation
because
series
out
of
a
Eventually
the
gets
column
richer
and
and
are
richer
condensed.
in
the
less
The
liquid
volatile
in
the
which
works
equilibria
the
up
the
vapour
column,
gets
ask
component.
Its
rich
in
the
more
boiling
volatile
point
of
they
increasingly
gradually
of
they
in
pass
range
points.
occur further
become
narrow
alone
1).
in
a
component.
increases.
117
10.6
Azeotropic
Learning outcomes
mixtures
Azeotropic
Some
On
completion
of
this
section,
be
able
interpret
boiling
point–
curves
mixtures
in
compare
the
a
of
from
azeotropic
qualitative
efciency
manner
by
simple
be
of
the
of
ethanol from
some
ideal
mixtures
of
liquid
separated
other
behaviour
are
ethanol
and
because
the
or
separation
can
mixtures
or
partly
which
deviate
separated
by
widely
fractional
from
ideal
distillation.
to:
composition

distillations
mixtures
compositions
However
,

other
you
behaviour
should
and
called
water
,
be
azeotropic
and
boiling
minimum.
compositions
cannot
ethanol
point
Figure
of
liquid
separated
mixtures.
and
shows
mixtures
Examples
They
diagram
the
which
fractional
benzene.
composition
10.6.1
by
boiling
are
HCl
cannot
shows
point
deviate
distillation.
a
and
be
widely
These
water
,
separated
distinct
maximum
composition
curve
for
a
water
mixture
of
mixture
having
ethanol
and
benzene.
Ethanol
is
the
more
volatile
component.
A
and fractional
a
minimum
boiling
point
is
formed.
distillation

understand
the
advantage
carrying
out
distillation
reduced
pressure.
of
under
tniop
gniliob
0
X
X
1
mole fraction
Figure 10.6.1
If
we
start
X
2
1
3
of
ethanol
Boiling point–composition curve for a mixture of benzene and ethanol
with
a
mixture
of
initial
mole
fraction
of
ethanol
X
and
apply
1
the
same
ideas
distillation

pure

a
about
results
benzene
mixture
fractional
distillation
as
in
Section
10.5,
fractional
in:
and
having
composition
X
2.
The
mole
fraction
of
ethanol
represented
by
X
is
0.54.
2
If
we
start
with
a
mixture
of
initial
mole
fraction
of
ethanol
X
,
fractional
3
distillation

pure

a
results
ethanol
mixture
in:
and
having
composition
X
2.
The
mole
fraction
of
ethanol
represented
by
X
is
again
0.54.
The
2
minimum
The
boiling
mixture
of
point
is
benzene
67.8 °C.
and
ethanol
represented
by
X
is
called
an
2
tniop
azeotropic
cannot
completely
gniliob
Azeotropic
is
a
mixture
or
of
constant
separate
mixtures
mixture
a
can
such
also
boiling
mixture .
mixtures
have
trichloromethane
by
can
fractional
maximum
and
Y
ou
boiling
propanone
see
that
we
distillation.
points.
(Figure
An
example
10.6.2).
Ethanol distillation
mole fraction
of
propanone
When
not
Figure 10.6.2
118
distil
pure
an
ethanol–water
ethanol
in
the
mixture
receiver
.
We
using
get
a
simple
mixture
distillation,
of
water
we
do
and
Boiling point–composition
curve for a mixture of trichloromethane
and propanone
we
get
ethanol.
many
The
times
process
to
get
a
is
not
very
very
high
efcient.
alcohol
We
would
content.
This
have
to
does
not
repeat
this
matter
too
Chapter
much
if
we
because
made
more
efcient
alcohol
making
alcohol
process.
constant
to
alcoholic
content
concentrated
because
Fractional
order
are
the
But
distillation
boiling
by
even
alcohol
pure
the
alcohol–water
the
ethanol.
fractional
a
mixture
produce
not
a
with
ethanol
an
with
as
be
of
silica
and
gel.
This
not
water
of
water
a
mole
removed
absorbs
the
The
pure
water
.
produces
a
%.
by
phrase
In
drinks
the
contains
drink
authorities
but
‘proof
This
used
method
partly
is
is
decompose
sometimes
because
called
the
it
used
can
to
distil
they
in
are
produce
distillation .
can
be
0.016 atm).
rubber
liquids
reduced
The
to
If
the
which
to
would
product.
value
of
is
is
(see
The
attached
the
vapour
shown
in
completely
pressure
distillation
purer
used
either
atmospheric
apparatus
the
apparatus
at
steam
a
not
70%
ancient
could
spirit’. The
that
alcohol.
test
collect
drink
mean
to
so
tax
was
It
that
on
poured
gunpowder.
be
lit,
the
If
the
spirit
gunpowder
was
‘proof ’.
pressure
distilled
preference
sometimes
vacuum
pressure
(about
if
reduced
an
does
applied
not
could
under
proof ’
alcoholic
over
Distillation
‘70%
comes from
shaking
water
techniques
be
more
with
Separation
Did you know?
can
produce
95.6
is
whisky
is
mixture
content
remaining
or
Ethanol
which
does
boiling
ethanol
rum
100%.
distillation
ethanol
the
such
to
distillation,
constant
mixture
mixture
need
fractional
forms
of
beverages
does
10
Section
method
to
a
It
10.7)
is
water
pressure
Figure
or
(1 atm).
of
also
pump,
water
10.6.3.
tubing
condenser
to
vacuum
pump
capillary
tube
10.6.3
Apparatus for distillation under reduced pressure. The capillary tube reduces
sudden movements of the liquid (‘bumping’) which often occurs in these distillations.
When
the
reduced.
distilling
of
pressure
We
can
impure
phenylamine
0.02 atm
The
is
reduced,
purify
the
phenylamine
is
boiling
phenylamine
reduced
to
under
77 °C
reduced
if
the
liquid
184 °C
pressure.
distillation
dimethyl
sulfoxide,
(CH
)
3
reduced
of
point
is
at
The
carried
is
also
1 atm)
boiling
out
at
by
point
about
pressure.
solvent
vacuum
point
(boiling
distillation
because
it
is
SO,
is
commonly
puried
by
2
more
stable
when
distilled
under
pressure.
Key points

An
azeotropic

Azeotropic
minimum
Fractional

Distillation
cannot
mixtures form
or

mixture
maximum
distillation
decompose
under
if
is
more
at
completely
constant
boiling
reduced
distilled
be
boiling
point
mixtures
depending
efcient
pressure
separated
is
atmospheric
than
used
on
which
the
repeated
to
distil
by
distillation.
have
either
a
mixture.
simple
distillations.
compounds
which
may
pressure.
119
10.7
Steam
distillation
Learning outcomes
Steam distillation
Immiscible
On
completion
of
this
section,
two
should
be
able
immiscible
do
not
liquids
mix.
the
understand
the
principles
vapour
pressures
of
the
pure
o

how
So
nitrobenzene
phenylamine
can
be
puried
the
total
steam
understand
distillation
the
use
of
of
in
simple
examples
distillation
industries
of
is
oils
and
equal
to
water
.
the
For
sum
of
components:
e.g.
than
p
B
pressure
The
o
p
is
higher
temperature
that
of
either
than
at
o
= p
+
T
p
H
O
2
the
which
vapour
the
component
oil
pressure
mixture
alone.
We
boils
can
of
either
is
take
of
and
oils from
of
in
with
to
distil
water
plant
and
oils
have
or
other
other
substances
contaminating
which
are
compounds
in
calculations
the
application
the fragrance
in
this
steam
them.
give
alone.
lower
immiscible

plant
distillation
advantage

+
A
vapour
component
therefore
by
is
pressure
o
= p
T
distillation
understand
and
example
vapour
of
p
steam
An
total
to:
the

liquids
you
the
This
through
a
increased
(Figure
extraction
process
liquid
and
is
called
which
the
is
steam
distillation .
immiscible
mixture
boils
at
a
with
When
water
,
the
temperature
steam
vapour
lower
is
bubbled
pressure
than
is
100 °C
10.7.1).
plants.
steam
p
total
condenser
)mta(
p
H
0
2
1
atm
steam
erusserp
generator
p
L
ruopav
X
100
substance
temperature
immiscible
(°C)
heat
with
water
water
Figure 10.7.1
Vapour pressure–boiling
e.g.
oil
in
lemon
peel
point curves for two immiscible liquids, L
oil
and water. The boiling point of the
mixture, X, is below that of water.
10.7.2
We
Steam distillation of a plant oil
can
from
Cut

Put

Bubble

Condense

Collect

Use
part
of
the
Bhutan,
a
small
state
in
the
H
6
peel
the
Mountains,
grass
steam
to
is
120
distillation
make
a
ask
mixture
plant
separating
distil
and
of
plant
oil
such
as
limonene
is:
sections.
add
just
enough
water
to
cover
the
peel.
mixture.
steam
oil/water
a
procedure
small
the
funnel
to
The
into
through
the
and
mixture
(see
plant
in
Section
a
oil.
receiver
.
10.8)
to
separate
the
plant
oil
water
.
distillation
is
used
to
purify
and
nitrobenzene,
dependent
perfumes.
of
lemon
C
2
Distillation
decomposition.
on
peel.
peel
into
steam
the
NH
5
points.
Himalayan
a
lemon
the
distillation
orange
compounds
such
as
phenylamine,
economy
C
of
the
from
Steam
large
the
steam
or

Did you know?
A
apply
lemon
H
6
at
a
lower
NO
5
,
which
have
relatively
high
boiling
2
temperature
reduces
the
risk
of
thermal
Chapter
Calculations
We
can
calculate
comparing
each
the
involving
the
mass
component
of
molar
of
the
of
and
mixture
a
liquid
liquid
in
from
present
steam
steam
in
the
distillation
distillation
distillate.
we
can
use
techniques
by
Since
behaves
o
independently,
Separation
steam distillation
mass
water
10
Raoult’s
law
and
the
equation
o
p
p
T
+
=
H
p
O
A
2
to
develop
a
third
equation:
n
p
H
O
H
2
____
O
2
_____
=
p
n
A
p
are
n
partial
are
the
pressures
number
of
mass
of
liquid
moles
of
of
liquid
A
A
A
and
and
water
water
.
( m)
_______________________
Since
n
=
molar
we
can
write
mass
this
of
liquid
equation
( M)
as:
p
m
H
O
/M
H
2
____
O
H
O
2
2
__________
=
p
m
A
Worked
When
nitrobenzene
mercury),
pressure
water
example
the
of
and
is
steam
distilled
distils
at
10 g
nitrobenzene.
is
of
733 mm
=
at
99 °C.
mercury.
nitrobenzene.
(M
A
1
mixture
water
/M
A
a
At
pressure
this
The
Calculate
of
distillate
the
1 atm
temperature,
(760 mm
the
contains
relative
vapour
40 g
molecular
of
mass
of
18).
water
Step
Step
1:
2:
Calculate
the
760 – 733
=
Substitute
vapour
27 mm
the
pressure
gures
p
into
m
nitrobenzene:
the
equation:
/M
water
water
_________
of
mercury.
water
___________________
=
p
m
nitrobenzene
733
/M
nitrobenzene
nitrobenzene
40/18
____
_____________
=
27
10/
M
Key points
nitrobenzene
733
18
____
So
M
=
×
10
________
×
=

122
Steam
distillation
is
used
to
nitrobenzene
27
40
separate
liquids
Worked
example
mixtures
or
to
of
extract
immiscible
oils from
2
plants.
Phenylamine
was
steam-distilled
at
98.6 °C
and
a
pressure
of
760 mm

mercury
(1 atm).
The
720 mm
mercury.
vapour
pressure
of
water
at
this
temperature
Steam
purify
The
distillate
contained
25 g
water
.
Calculate
the
phenylamine
in
the
is
used
to
high
boiling
point
liquids
mass
such
of
distillation
was
as
phenylamine
and
distillate.
nitrobenzene.
=
(M
18,
M
water
=
93)
phenylamine

Step
1:
Calculate
760
–
the
720
=
vapour
40 mm
pressure
of
For
two
total
phenylamine:
the
mercury.
immiscible
vapour
vapour
liquids
pressure
pressures
=
of
the
sum
the
of
pure
components.
Step
2:
Substitute
the
gures
into
the
equation:

p
m
water
be
M
phenylamine
720
masses
can
calculated from
the
moles,
n,
/M
phenylamine
phenylamine
of
each
immiscible
distillate
25/18
____
molecular
water
___________________
=
p
Relative
/M
water
_________
by
the
liquid
in
the
equation:
____________
=
40
m
/93
p
phenylamine
n
water
water
_____
_____
=
p
n
A
25
m
=
A
40
___
So
____
×
×
93
=
7.2 g
phenylamine
18
720
121
10.8
Solvent
Learning outcomes
On
completion
should
be
able
of
this
extraction
Introduction
section,
Solvent
extraction
solvent.
A
understand
which

based
the
solvent
undertake
on
principles
extraction
simple
on
is
based
calculation
partition
out
an
describe
simple
experiments
partitioning
two
be
solvent
used
to
which
separate
is
two
immiscible
solutes
with
dissolved
the
rst
is
in
used
a
chloride
immiscible
a
the
solutes
separating
solution
(soluble
on
solute
Put
the
in
from
funnel
of
the
(see
iodine
water)
aqueous
solvent
separation
a
using
of
rst
Figure
(very
and
solvent.
we
10.8.1).
slightly
want
The
to
extraction
For
soluble
example,
in
separate
water)
the
is
to
if
we
and
iodine
carried
have
sodium
we:
coefcients
based
of
one
aqueous


second
to:
extract

can
you
which

immiscible

a
mixture
in
the
separating
funnel
then
add
another
is
with
water
between
good
solvent
for
iodine,
e.g.
hexane.
solvents.

Shake
The
the
the
will
sodium

Run

Repeat
off
been

contents
iodine
The
the
the
go
of
chloride
bottom
process
removed
solvent
the
into
separating
the
funnel
component
remains
in
the
in
then
which
aqueous
let
it
the
is
layers
more
settle.
soluble
and
layer
.
layer
.
with
from
the
(hexane)
fresh
solvent
aqueous
is
until
nearly
all
the
iodine
has
layer
.
evaporated,
leaving
the
iodine
as
a
solid.
separating
funnel
solution
shake
hexane
of
iodine
in
solution
solution
of
of
salt
and
in
Figure 10.8.1
hexane
iodine
in
salt
water
water
When an aqueous solution of salt and iodine is shaken with hexane, the
iodine moves to the hexane layer
The distribution
Solvent
extraction
immiscible
between
The
immiscible
concentrations
equal
depends
solvents.
two
coefficient
volume
present.
of
on
the
amount
solvents
For
relative
of
solubility
solute
depends
example,
trichloromethane,
if
on
we
the
shake
,
CHCl
which
in
a
is
of
a
solute
in
partitioned
two
(divided)
equilibrium
aqueous
ammonia
separating
funnel,
with
an
ammonia
3
molecules
move
between
the
two
layers
(CHCl
NH
3
The
concentration
titration.
The
distribution
of
coefficient
in
NH
layer
for
partition
equilibrium
is
established.
(aq)
3
each
constant
or
Y
an
3
ammonia
equilibrium
)
until
this
can
be
process
coefficient ,
K
determined
is
.
called
The
by
the
value
of
D
vary
with
temperature.
Most
values
[NH
are
quoted
at
K
may
D
298 K.
(aq)]
_____________
3
For
this
equilibrium
K
=
=
23.3
D
[NH
(CHCl
3
Note
that
partition
expression
122
which
coefcients
has
the
are
higher
)]
3
usually
quoted
concentration
on
for
the
the
equilibrium
upper
line.
Chapter
Calculations
using the distribution
10
Separation
techniques
coefficient
Exam tips
Worked
example
1
In
A
solution
of
butanedioic
acid
(BDA)
in
ether
contains
3
BDA
ether
.
This
solution
is
shaken
with
the
mass
of
BDA
extracted
into
the
of
water
BDA(ether)
Y
BDA(water)
1:
Calculate
the
concentration
in
each
is
6.7
the
to
m
is
Step
2:
the
layer
(4.0
×
mass
so
Substitute
m
values
1000
concentration
of
volume
are
as
the
long
same.
is
because
So,
as
long
are
the
the
1000
cancels.
as
the
units
of
same,
the
expression
volume
can
be
1000
[BDA(ether)]
–
like
this.
m)
=
×
1000
20
in
is
the
_________
=
50
ether
the
units
simplied
m
(if
ignore
component.
___
[BDA(water)]
can
layer
.
D
Step
you
water
.
This
for
K
2,
relating
50 cm
as
Calculate
Step
in
3
of
20 cm
4.0 g
the
water
,
this
subtracted
into
the
must
from
the
equilibrium
have
mass
come
in
from
the
the
ether
layer)
expression.
m
___
Exam tips
50
[BDA(water)]
____________
K
=
6.7
=
D
[BDA(ether)]
(4.0
–
m)
_________
Remember
20
m
=
the
3.8 g
mass
two
example
of
extractions
using
single
a
solvents
A
using
larger
and
B,
small
volume
where
of
portions
solvent.
for
K
[B]/[A]
of
solvent
We
=
can
see
are
more
this
by
efcient
than
comparing
two
we
the
have
15 g
amount
of
of
solute
solute
in
3
50 cm
transferred
m
=
of
to
(15
___
4
lot
in
of
do
not
solute for
as
solute
the rst
use
3
If
are
calculating
extracted
use
the
using
the
same
second
you
will
used
have
in
the rst. A
been
extraction. You
removed
should
4.
D

you
2
extraction
Several
if
solute
extractions,
amount
Worked
that
of
A
B
–
and
is
shake
given
it
with
50 cm
of
B,
the
rst
amount
extraction
removed
by:
in
of
solute
MINUS
the rst
in
the
the
amount
extraction.
m)
________
÷
=
50
12 g
50
3

If
we
extract
extraction
the
solute
using
two
portions
(15
m
___
the
rst
second
–
m)
________
÷
=
=
50
the
25 cm
gives:
4
and
of
extraction
10 g
25
gives:
Key points
m
(5
___
4
=
the
total
extracted
is
m)
÷
=
50
So
–
_______
10
3.3 g

25
+
3.3
=
Solvent
the
13.3 g
in
Some
uses of
solvent
extraction

two
The
the

Ether
extraction
is
often
used
in
chemistry
to
separate
products
extraction
relative
immiscible
distribution
constant
synthesis
from
water
.
The
ether
layer
oats
above
the
The
evaporate
useful

Cosmetic
cosmetic
In
the
the
is
separated
organic
product
the
creams
metallurgy
are
often
different
and
ideas
chemistry
the
ether
behind.
volatile
have
to
they
The
or
take
use
(very
ammable)
technique
unstable
account
in
the
to
of
is
is
left
immiscible
relative
formulation

of
between
uses
are
molten
ideas
of
used
metals
relative
to
determine
and
solid
solubility
from

The
how
readily
industrial
food
pollutants
are
taken
up
into
the
a
relates
of
a
solute
how
if
metals.
between
the
two
of
solute
solvent
can
distribution
extracted
solution
be
by
calculated
coefcient
is
known.
when
Several
extractions
using
small
groundwater
portions
of
efcient
than
solvent
are
more
wastes.
industry
of
is
particular
which
particular
uses
solvent
extraction
to
analyse
the
compounds
in
fats
and
aqueous
using
a
single
larger
relative
volume
solubility
coefcient
a
solvents.
amount
from

deducing
The
another
extraction
on
solute
liquids.
concentration
partitioned
especially
heat.
the
a
to
colourings.
solvent
distributed
Environmental
is
solvents
hair
of
and
product
required
manufacturers
in
impurities

layer
leaving
when
solubility

ether
at
of
aqueous
the
layer
.
based
of
temperature
organic
is
solubility
of
solvent.
solutions.
123
10.9
Distillation
and
solvent
extraction:
applications
Learning outcomes
Distillation
Rum
On
completion
of
this
section,

be
give
of
able
examples
the
of
in
the
the
rum
understand
can
be
molasses
(a
by-product
of
sugar
rening)
or
from
sugar
juice.
application
Y
east
and
water
are
added
carbohydrates
for
the
producers
particular
to
yeast
the
to
molasses
feed
on)
to
(which
start
contains
the
the
fermentation.
Different
petroleum
industry
use
strains
of
yeast
but
many
use
the
foam
from
and
previous
the fragrance

from
industry
to:
distillation
industry,
made
rum
you
cane
should
is
in the
fermentations.
industry
how
acids
separated
by
and
H
C
bases
6
O
12
(aq)
→
2C
6
H
2
OH(aq)
+
2CO
5
(g)
2
solvent
When
fermentation
is
complete
the
aqueous
mixture
is
distilled.
extraction
Some

select
appropriate
methods
pot
separation
when
given
producers
still
and
the
of
the
and
chemical
components
of
a
avours
producers
materials
vapours.
that
The
which
are
higher
up
use
The
fermentation
Many
rings.
Did you know?
of
the
earliest
is
in
a
give
a
rising
cooler
.
the
references
to
‘The
of
too
Either
to
high.
they
extract
make
. . .
distilled,
in
this
the
is
island
made
of
vapours
reach
a
area
which
condenses
they
like
surface
vapour
directly
rum
to
the
its
is
in
for
is
of
a
type
pot
in
alcohol
higher
levels
progressively
Section
of
fractional
stills.
condensation
higher
the
become
(see
This
series
It
of
than
of
is
the
the
richer
lled
with
rising
the
column,
in
alcohol
the
10.5).
industry
are
oily
volatile
hydrocarbon-based
in
nature.
oils
or
solvent
extraction
for
the
Some
oils
are
extraction
compounds
plants
or
contain
easily
steam
often
only
denatured
if
distillation
with
very
aromatic
small
temperature
is
commonly
is
used
a
hot,
hellish
a
time
to
the
raw
extract
material
the
is
aromatic
immersed
in
compound.
the
solvent
Hexane
and
and
is
ether
a
lot
are
of
two
water
,
of
the
two
solvents
layers
are
most
commonly
formed
–
an
used.
aqueous
If
the
layer
plant
(arising
and
the
water
present
in
the
plant
material)
and
an
organic
layer
which
liquor’.
contains
the
extracted
or
desired
from
distillation.
fragrance
material
Steam
leaves
and
as
it
waxy
rose
is
oil.
Other
lower
low
is
of
to
of
be
in
which
extracted
Ethanol
is
not
Some
remains
with
fragrances
after
ethanol,
usually
used
solvent
e.g.
to
can
be
extraction
jasmine
extract
fresh
plant
water
.
used
for
plants,
than
compounds.
‘concrete’
can
soluble
stems
sufciently
extracting
since
100 °C.
prevent
the
oil
The
oils
and
distils
fragrances
off
with
temperature
decomposition
of
the
of
the
from
water
distillation
fragrance
owers,
at
is
molecules.
methods
V
acuum
which
the
mixture
These
distillation
and
temperatures
124
the
sugar
from
terrible
applied
fragrances.
solvent
contains
canes
is
giving
chief fuddling
dimethyl
Rumbullion
Heat
document from
shaken
(drink)
are
distillation.
behaves
large
The
still
fragrances
Many
column
mixture
amounts
In
Barbados.
stills).
compounds
evaporate.
column
The fragrance
(1651)
(pot
aroma
mixture.
distillation.
rum
batches
and
properties
Other
One
in
alcohol
the
characteristic
physical
work
of
distillation:
are
easily
This
denatured
can
if
be
used
fractional
to
extract
some
distillation
is
components
used.
Chapter
Fractional
to
remove
distillation:
If
the
contaminating
fragrance
molecules
molecules
with
less
are
stable,
pleasant
this
is
10
Separation
techniques
used
odours.
Petroleum distillation
Crude
oil
different
is
a
mixture
components

Some
of

Primary
the
distillation
fractional
is
separated
the
middle
into
a
number
of
distillation:
removed
separates
distillate,
fractionation
solvents to
salts
larger
then
are
It
of
by
oil
simple
into
distillate
distillation.
several
and
groups
residue)
of
by
are
discussed
extract
generally
organic
is
soluble
molecules
tend
in
to
further
acids
water
.
be
in
and
in
12.1.
bases
Neutral
insoluble
Section
molecules,
retaw
Ionic
(light
gases
types
distillation.
Petroleum
Using
hydrocarbons.
several
dissolved
components

of
by
especially
water
.
B
ionic
ni
a
as
phenylamine,
mixture
of
an
organic
the
acid
following
–
H
C
6
If
we
OH
Y
C
5
add
H
6
a
slightly
phenylamine,
the
such
as
phenol
equilibria
and
an
organic
+
+
H
and
C
5
H
6
stronger
such
exist:
+
O
base
base
phenylamine
to
a
ytilibulos
In
NH
5
+
H
Y
C
2
mixture
remains
+
of
H
6
phenol
uncharged
but
NH
5
3
A
molecular
molecular
and
the
7
phenol
pH
becomes
but
the
deprotonated.
phenylamine
The
is
phenol
present
is
only
present
as
in
the
form
of
an
ionic
salt
Figure 10.9.1
molecules.
The molecular and ionic
forms of organic acids (A) and bases (B) at
H
C
6
OH
+
OH
→
+
OH
→ C
C
5
H
6
O
+
H
+
H
5
different pH values
O
2
+
H
C
6
If
we
add
an
acid,
phenylamine
NH
5
the
3
phenol
becomes
H
6
remains
protonated.
in
The
NH
5
its
2
O
2
molecular
phenylamine
form
is
in
but
the
the
ionic
form.
+
C
H
6
O
+
H
+
H
→ C
5
H
6
OH
5
+
H
C
6
We
can
separate
the
NH
5
ionic
+
→ C
2
form
H
6
from
the
NH
5
3
molecular
form
by
solvent
extraction:

A
mixture
solvent

The

An
of
e.g.
organic
acid
and
dichloromethane
mixture
is
poured
into
a
organic
or
base
is
dissolved
ethoxyethane
separating
(an
in
a
suitable
ether).
Key points
funnel.

aqueous
solution
of
another
acid
(or
base)
is
added
to
adjust
Distillation
fractional
pH
so
that
the
molecular
or
ionic
form
you
want
is
The
water/solvent
mixture
is
shaken
and
the
phase
containing
in
either
the
molecular
form
(in
non-aqueous
solvent)
form
(in
the
aqueous
layer)
is
separated
production
and
suitable
method of
depends
of
spirits
such
as
Many
perfumes
extracted
and fragrances
or
using
steam
solvent
extraction.
separation

This
or
in
whisky.
distillation
a
used
off.
are
Selecting
is
or

ionic
process
the
rum
compound
batch
distillation
present.
the

by
the
on:
Acids
or
and
bases
puried
using
can
be
extracted
solvent
extraction.


Solubility:
An
dissolving
the
Boiling
be
points:
separated
insoluble
latter
A
by
solid
then
mixture
fractional
can
be
separated
from
a
soluble
solid
by
ltering.
of
liquids

with
different
boiling
points
can
The
selection
method
depends
distillation.
boiling

Solubility
in
different
solvents:
Use
solvent
of
of
a
suitable
separating
on
substances
properties
points
and
such
solubility
as
in
extraction.
particular
solvents.
125
Exam-style
Answers to
all
exam-style questions
–34
h
=
6.63
×
10
8
J s;
c
=
3.0
×
10
can
questions
be found on the
–
Module
2
accompanying CD
–1
m s
ii
The
equilibrium
system
can
be
represented
by
the
equation
Multiple-choice questions
Br
Y
Br
2(H
O)
2
1
The
diagram
hydrogen
n
=
is
3
to
shows
some
atom. An
energy
of
the
electron
level
the frequency
of
n
=
the
1,
energy
levels
moves from
emitting
emitted
a
of
a
energy
iii
level
At
a
temperature
partition
2(CHBr
above
coefcient
)
3
25 ºC,
would
the value
of
change from
the
66.7
.
photon. What
A
only
C
ii
i
B
i
D
i,
and
ii
radiation?
and
iii
ii
and
iii
–19
n = 3
2.40
×
10
J
6
n
The
actual
a food
–19
amount
sample
was
of
potassium
ions
4.25%. The food
present
sample
in
was
J
analysed
by four
different
approaches,
four
different
experimenters,
who
repeated
times. The
results
are
given
experimenter’s
results
show
each
using
test
below. Which
–19
n
J
14
A
8.27
×
10
C
3.29
×
10
15
Hz
B
2.93
×
10
Hz
D
3.65
×
10
15
2
What
is
the
wavelength
3.40
×
Hz
15
energy
of
of
nm?
650
a
light
photon
and
the
highest
degree
A
5.21,
5.22,
5.21,
B
5.45,
4.
11,
4.25,
C
4.25,
4.24,
D
4.20,
4.
15,
5.21,
5.23
4.84,
6.43
a
4.23,
4.35,
4.26,
4.30,
4.27
4.25
–29
10
J
B
1.44
×
D
6.63
10
J
3
–19
C
3.06
×
7
–19
10
J
×
10
In
a
There
are four
types
of
back-titration,
–3
of
25.0 cm
1.00 mol
dm
HCl
J
was
3
of
precision?
Hz
with
–36
A
accuracy
electromagnetic
radiation
in
added
to
an
agent CaCO
in
antacid
a
containing
conical ask. The
the
active
excess
HCl
was
3
the
list
–3
below:
titrated
with
0.55 mol dm
NaOH
solution
and
it
3
i
X-ray
ii
infrared
iii
microwaves
iv
ultraviolet
was found
a
that
complete
a volume
reaction.
agent CaCO
,
does
of
How
the
27
.3 cm
many
antacid
was
moles
required for
of
the
active
contain?
3
Which
of
the
lists
below
gives
the
radiation
in
order
–2
A
of
increasing
1.5
×
–3
B
10
5.0
×
10
wavelengths?
–2
C
A
i,
iv,
C
iv,
ii,
iii
B
ii,
iv,
D
iii,
iii,
i,
ii
i,
ii
×
10
D
7
.5
×
10
i
8
iii,
2.5
–3
A
1.5234 g
sample
of
impure
BaCO
was
reacted
with
3
iv
excess
dilute
hydrochloric
acid. The CO
liberated
2
4
For
a
system
where
a
solute
R
is
distributed
between
was
two
solvents,
and
R
has
the
same
absorbed
both
solvents,
the
equilibrium
process
may
is
Y
solvent
of
to
weigh
the
%
of
barium
in
the
sample?
0.
1425 g.
[Relative
mass C
=
12.01; O
=
16.00;
Ba
=
137
.33]
as:
R
Which
and found
be
atomic
represented
NaOH
molecular form
What
in
by
41.94
%
C
29.
19
A
solution
B
9.35
%
D
90.65
R
1
these factors
A
solvent
would
2
affect
the value
of
the
%
%
–3
9
of
of
KMnO
molarity
0.
102 mol dm
4
partition
3
coefcient?
required
30.35 cm
to
react
completely
with
3
i
the
mass
of
ii
the volume
iii
the
the
of
solute
the
originally
in
solvent
1
22.24 cm
What
solvents
is
MnO
i
and
C
i,
ii
B
ii
and
and
iii
D
only
1
mole
of
molarity
ratio for
the
0.348 mol dm
reaction
.
between
and X?
MnO
:
2 X
B
2
MnO
4
iii
C
ii
the
solution X
4
temperature
A
A
–3
of
0.4
:
MnO
1 X
D
5
MnO
4
iii
10
Propanone
:
5 X
:
2 X
4
4
shows
absorption
maxima
at
λ
max
5
The
partition
coefcient for
between
Br
water
and
2
189 nm
and
λ
279 nm. What
type
of
transition
max
tribromomethane
at
25 ºC
is
66.7
,
where
the
bromine
responsible for
is
in
the
same
molecular form
in
both
solvents
a
higher
these
i
If
solubility
statements
the
is
in
tribromomethane. Which
of
true?
concentration
of
in CHBr
Br
2
,
then
the
these
189
nm
λ
max
279
max
A
π
→
π*
n
B
σ
→
π*
σ
C
n
→
π*
n
D
n
→
π*
σ
→
→
π*
σ*
is
3
–3
0.250 mol dm
of
concentration
in
H
O
is
→
σ*
2
–3
3.75
126
×
10
–3
mol dm
absorptions?
and
λ
has
each
→
π*
nm
is
Module
iv
Structured questions
11
a
Distinguish
between
the
terms
What
would
drops
of
and
‘titrimetric
analysis’.
identities
and
the
of
liquid
questions
the rst few
remaining
in
distillation ask,
if
the following
mixtures
[2]
are fractionally
b
the
distillate
Exam-style
‘gravimetric
the
analysis’
be
2
distilled?
A sample was prepared by mixing a number

0.79
mole fraction
of

0.25
mole fraction
acetone.
acetone
[2]
of substances and the entire sample was then
[2]
dissolved in distilled water in a 250 ml volumetric
ask. Two students, Julia and Jenny, were then
13
a
UV-visible spectroscopy and IR spectroscopy are
asked to determine the mass of calcium present in
two of the spectroscopic methods of analysis.
the 5.524 g sample by using different approaches.
Compare these methods in terms of the type of
Julia titrated three 25.0 ml aliquots of the solution
information that can be obtained from their use. [4]
–3
with 0.
100 mol dm
EDTA and found that the
2+
b
3
mean titre was
37 . 10 cm
The
concentration
of
in
FeSCN
a
solution
is
. Jenny placed 150 ml in
a beaker and added excess Na
CO
2
to
be
at
λ
determined
by UV-visible
spectroscopy,
solution. She
3
580 nm
and
using
a
1.00 cm
cell. A
max
then collected, dried and weighed the precipitate,
calibration
curve
was
plotted for
the
system
and
which had a mass of 2.403 g.
the
[Relative
atomic
mass Ca
=
40.078; O
=
molar
absorptivity
3
=
was found
to
15.999;
be
C
coefcient
7
.00
×
10
3
dm
–1
mol
–1
cm
.
Five
students
each
12.011]
3
diluted
i
Based
on Julia’s
approach,
what
is
the
mass
ii
in
the
Julia’s
iii
sample?
Calculate
What
the
%
the
iv
Based
of
calcium
in
the
sample from
[1]
identity
of
the
of Ca
in
the
placing
10.0 cm
100 cm
water
up
volumetric ask
of
each
the
and
the
to
the
graduation
and
adding
diluted
results
are
mark. The
distilled
solution
shown
was
in
the
then
absorbance
determined
table
below.
precipitate
by Jenny?
on Jenny’s
by
3
a
Student
obtained
solution,
[4]
approach.
was
original
of
in
Ca
the
1
2
3
4
5
0.552
0.564
0.550
0.554
0.540
[1]
approach,
what
is
the
mass
sample?
Absorbance
[4]
at
λ
580 nm
max
v
The
actual
mass
of Ca
in
the
sample
prepared
i
was
1.518 g.
From
a
consideration
of
Explain
how
coefcient,
relative
error,
comment
on
the
accuracy
and Jenny’s
results.
Suggest ONE factor
that
could
have
mass
obtained
of
molar
absorptivity
determined from
the
curve.
[1]
Calculate
by Jenny
to
be
the
mean
absorbance
and
use
this
caused
to
the
was
[2]
ii
vi
ε,
of
calibration
Julia’s
the value
the
higher
determine
the
average
concentration
in
than
–3
mol
the
expected value.
in
dm
the
diluted
solution.
[2]
[1]
2+
iii
12
a
Explain
what
is
meant
by
the
vapour pressure
of
liquid.
a
i
How
does
the
an
increase
boiling
in
point
external
of
a
pressure
concentration
of
FeSCN
in
the
[3]
liquid?
Explain
why
this
Find
the
standard
deviation
of
the
students’
results.
[2]
[1]
c
c
the
solution?
[2]
affect
ii
is
original
iv
b
What
occurs.
[2]
The
IR
spectrum for
the
compound
ethyl
ethanoate
O
For the two-component system acetone and
carbon disulphide, an azeotrope is formed at mole
CH
C
C
CH
3
CH
2
3
fraction 0.36 of acetone, and has the boiling point
–1
shows
absorption
bands
at
3000–2850 cm
,
of 312 K. The boiling point of pure acetone is 329 K
–1
1742 cm
–1
and
1241 cm
.
and the boiling point of pure carbon disulphide is
Identify
319 K.
rise
i
Sketch
this
the
boiling
point

intermolecular forces

total volume
these
Would
the
happens
of
two
the
to
of
bands.
bonds
that
most
likely
give
[3]
the:
attraction
liquid
liquids
mixing
exothermic
these
of
[3]
Explain
when
what
to
type
curve for
mixture.
ii
iii
composition
the
be
process?
are
an
mixed.
endothermic
[2]
or
[1]
127
11
Aluminium
11.
1
Locating
Learning outcomes
chemical
industry
Factors that
influence the
location of
chemical
industry
On
completion
should
be
able
of
this
section,
you
to:
In
recent
the

understand
inuence
the
industrial

describe
the factors
location
some
general
in
the
of
there
has
been
aluminium
much
smelting
discussion
plants.
in
There
the
are
Caribbean
many
about
factors
that
that
of
inuence
the
location
Nearness
to

ores
of
chemical
industry,
some
are
discussed
here:
an
plant
requirements
years,
building
safety
Metal
chemical
and
the
takes
source
are
a
of
heavy,
lot
of
raw
so
materials
to
(including
transport
them
a
water
long
supply):
distance
is
expensive
energy.
industry.

W
ater
is
used
manufacture
close.
This
Bromine
being
Did you know?
are
The
traditional
chemical
often found
near
ports
easy
import
of
raw
export
of
plants
products. The
which
produce
such
as
less
affected
mentioned
by
So
plants
seawater
,
bromine
used
in
heating
water
are
so
it
near
makes
the
In
So
be
sea.
to
set
addition
industries
most
acid
should
the
sense
sea.
chemical
medium.
sulphuric
supplies
located
near
most
e.g.
up
a
to
for
chemical
plants
rivers.
network:
the
products
away
T
o
from
transport
needed.
For
environmental
the
the
factory,
raw
good
materials
road
and
to
rail
the
links
reasons,
heavy
materials
such
as
metal
siting
are
best
transported
by
rail
rather
than
road,
to
minimise
pollution.
speciality
metal
ores
are
transported
by
ship,
so
the
nearness
to
a
port
or
pharmaceutical
specially
is
near
communications
Many
chemicals
or
is
a
and
ores
of
sea
as
processes,
ethanol.
from
water
or
many
materials
are
and
solvent
the
of
chemical
manufacturing
material,
a
in
which
factory
allow
some
manufactured
raw
near
material
production
why
plant
as
raw
industry
Good
is
a
cooling,
a
and
is
is
chemical
as
built
harbour
is
very
important.
the factors
Labour:
here.
those
Employees
in
many
chemical
provide
plant
such
Availability
out
at
high
in
other
the
chemical
areas
should
be
of
industry
tend
manufacturing.
near
enough
to
a
to
The
be
more
location
centre
of
skilled
of
than
the
population
that
can
people.
of
cheap
energy:
temperatures,
Many
e.g.
chemical
smelting
reactions
metals.
Many
can
only
others
be
need
carried
heat
to
Chemical industry in the Caribbean
give
Cuba
Trinidad
Nickel
and
Tobago
Petroleum
Ammonia
an
economic
synthesis
of
separation
rate
of
ammonia
processes
conversion
and
also
making
require
of
reactants
sulphuric
heating,
to
acid.
e.g.
products,
e.g.
Purication
and
distillation.
and
Gas
and
oil
are
used
often
used
as
heat
sources
in
industry.
Although
gas
fertilisers
and
oil
can
be
transported,
it
makes
more
economic
sense
to
site
a
Pitch
factory
or
plant
near
an
oil
renery
or
close
to
a
gas
pipeline.
Most
oil
Petroleum
reneries
are
near
the
coast
because
the
petroleum
is
transported
from
Methanol
the
producing
countries
in
ships.
Iron
Jamaica
Guyana
Iron
Bauxite
Bauxite
to
and
and
make
steel
the
plants
coke
are
often
necessary
sited
for
the
near
deposits
reduction
of
of
the
coal
iron
which
are
used
ore.
alumina
Electrolysis
the
of
aluminium
electrolyte
energy
is
sources
molten.
expensive,
of
The
If
128
it
plant
is
(i)
and
power
social
should
the
is
requires
provided
aluminium
hydroelectric
Environmental

so
oxide
This
or
smelting
close
to
amounts
electrical
plants
the
of
energy
heating.
are
often
to
keep
Electrical
sited
near
coast.
factors:
preferably
process
large
by
carried
not
out
be
built
should
in
be
an
in
area
the
of
natural
national
beauty.
interest
Chapter
(ii)
there
restore
should
the
area
be
no
alternative
when
the
factory
sites
is
(iii)
no
there
longer
should
be
is
a
plan
to
Safety
in the
11
Aluminium
chemical
viable.
industry

It
should
affected
not
by
be
the
transporting
sited
fumes
raw
so
close
or
noise
material
to
and
a
(i)
centre
from
of
the
population
factory
(ii)
that
from
people
are
Care
lorries


It
should
the
be
factory
sited
to
damage
minimise
the
the
possibility
environment,
e.g.
that
waste
waste
products
products
do
not
from
rivers
and
harm
the
area,
it
people
were
and
historical
makes
and
it
the
to
set
environment
established
near
to
production.
the
If
up
is
there
a
is
new
industry
factory
minimised.
coalelds,
where
already
because
In
the
there
the
past,
were
existing
impact
many
already
in
country
grants
Political
also
play
a
and
tax
part
on

factories
aluminium
centres
factors
such
as
the
availability
the
Government
in
the
in
incentives
the
to
location
develop
of
a
of
T
rinidad
of
vapours/waste
particular
and
T
rinidad
T
obago
near
regions
of
coastal
the
to
set
up
of
an
La
of
the
ammable,
pipes
and
chemical
weakening
pressure
Problems
town
in
be
radioactive
of
the
plant
structure
vessels.
a
can
access
to
be
overcome
proper
including
and Tobago?
wanted
the
may
or
of
factory.
smelter for Trinidad
south
or
of
safety
protective
and
access
by:
clothing
suits,
to
face
oxygen
aluminium
and
smelter
harmful
of
corrosion
masks
The
of
which
vessels

An
prevent:
reactants/products
leakage
explosive
the
of
government
to
get

industrial
taken
wildlife.
factors:
easier
be
leakage
gases
Political
to
poisonous

into
has
products.
Brea.
chemicals
to
neutralise
This
spillages
would
this

be
of
advantage
location
The
raw
to
the
economy
of
the
country.
The
advantages
of

regular
checking

checking
materials
can
be
sourced
nearby;
puried
aluminium
be
corrosion.
transported
from
Jamaica
and
bauxite
ore
is
available
the
conditions
of
oxide
pressure
can
for
are:
vessels
from

monitoring
the
working
Guyana.
environment

It
is
near
the
sea
so
water
is
readily
available
and
raw
materials
can
using
specic
be
sensors
transported
by
ship.


There
is
already
industry
present
in
the
area
–
the
T
rinidad
Lake
checking
that
instrumentation
of
is
working
correctly.
Pitch.

Finance
and

a
was
loan
The
project
port
and
required
This
available
from
the
would
provide
new
power
were
going
project
has
from
the
Chinese
work
station
to
be
currently
Chinese
company
Government
to
for
many
provide
was
people
the
involved
also
huge
in
the
deal
available.
especially
amount
of
as
a
new
electricity
built.
stalled
Key points
however
,
for
various
reasons:


Environmentalists
surrounding


Some
local
The
material
arsenic

people
the
The
plant
and
is
roads
about
the
damage
to
the
coastline
and
are
worried
close
lines
are
other
to
the
to
about
the
about
substances
the
site
are
the
town
smelter
worried
toxic
leading
on
materials,
too
that
people
and
worried
location
depends
land.
that
time
are
The
pots
the
in
not
pollution
of
La
in
needs
a
the
fumes
and
replacing
from
the
from
time
to

cyanide,
pots.
suitable
and
scale
chemical
industry
the
Caribbean
has
some
these
are
not
present
in
a
large
scale.
The
main
reserves
worthwhile
large-scale
alumina
ease
production
industries
and
natural
production
of
metals
such
as
nickel
in
gas
petroleum/
in Trinidad
are
and Tobago.
The
chemical
amounts
to
merit
chemical
industry
is
industry
should
and
tight
safety
requirements
extraction
to
on
energy,
environmental
production
have
copper
,
raw
in the Caribbean

Although
industry
of
ammonia/fertiliser
important
Large
and
important
Jamaica,
condition.
source
social factors.
Bauxite
are
chemical
available
transport,
and
Brea.
dangers
the
from
of
of
the
eliminate
possibilities
of res,
processing
explosions
or
release
of
toxic
bauxite.
materials.
129
11.2
Aluminium
Learning outcomes
production
Introduction
Aluminium
On
completion
of
this
section,
7.5%
should
be
able
describe
of
the
the
crust
most
and
abundant
is
present
metal
the
processes
involved
slate.
It
aluminium
is
extracted
oxide,
e.g.
from
bauxite
gibbsite
O
Al
2
in
the
production
of
its
the
Earth’s
with
silica
crust.
in
It
clay
,
forms
shale,
about
granite
ores,
·3H
3
which
O,
contain
boehmite
Al
2
hydrated
O
2
·H
3
O.
2
aluminium
Aluminium
from
in
combined
to:
and

is
you
is
obtained
from
bauxite
in
two
stages:
ores

describe

explain
how
why
bauxite
is

Purication

Electrolysis
of
bauxite
to
make
aluminium
oxide
(alumina).
puried
of
the
puried
alumina.
aluminium
impurities
production
requires
a
high
energy
consumption.
alumina
Al
O
2
3
electrolysis
bauxite
aluminium
production
Did you know?
NaOH
cryolite
electrical
energy
It
has
that
been
much
contains
known
of
an
associated
It
about
was
1943
recognised
land
the
not,
that
and
the
red
earth
limestone
however,
its
until
signicance
the Jamaica
started
to
1820s
in Jamaica
aluminous
with
rocks.
company
the
since
The
main
of
extracting
bauxite’
3–25%
iron( III)
these
has
in
bauxite
1–4%
oxide
and
silica
are
oxides
and
1–7%
very
of
silicon,
little
iron.
iron
‘Red
and
titanium.
bauxite’
has
silica.
Alumina
production
the
hydroxide
is
used
to
dissolve
the
aluminium
oxide
from
the
ore
aluminium
and
from
impurities
‘White
Sodium
possibility
Steps in the extraction of aluminium from bauxite
was
Bauxite
investigate
Figure 11.2.1
separate
the
impurities.
Approximately
2.5 tonnes
of
bauxite
are
rocks.
needed
to
make
1 tonne
of
puried
alumina,
O
Al
2
iron
oxide
O
(Fe
2
(SiO
)
),
titanium
dioxide
(TiO
3
present,
)
and
.
In
order
to
remove
the
3
most
of
the
silicon
dioxide
2
the
bauxite
is
treated
with
concentrated
sodium
hydroxide.
2
Aluminium
oxide
basic
do
oxides
Stage
is
not
1: Powdered
pressure
amphoteric,
dissolve
bauxite
(4 atm)
in
is
at
so
it
dissolves
sodium
mixed
with
140 °C.
in
hydroxide
This
10%
sodium
and
are
NaOH
takes
about
hydroxide.
ltered
and
1–2
The
off.
heated
hours
under
to
complete.
O
Al
2
+
2NaOH
→
2NaAlO
3
Silicon
dioxide
reaction
Stage
with
is
sodium
silicate
2: The
sodium
aluminate
settle
3: The
and
and
sodium
agitated
Slow
cooling
H
formed
metal
are
is
is
during
aluminate
then
soluble
oxides
ltered
with
either
O
2
aluminate
or
prior
to
this
step
by
hydroxide.
The
to
Stage
removed
sodium
contaminating
+
2
sodium
are
removed
in
not.
sodium
The
by
precipitation.
hydroxide
impurities
but
are
allowed
off.
is
‘seeded’
with
pure
aluminium
oxide
air
.
produces
a
precipitate
of
pure
aluminium
oxide
trihydrate.
+
2NaAlO
2
Stage
4: After
36 hours
dehydrated
recycled.
130
in
O
→
Al
2
the
a
4H
alumina
rotary
O
2
kiln
·3H
3
O
+
2NaOH
2
is
removed
by
at
1000 °C.
The
vacuum
ltration
sodium
then
hydroxide
is
Chapter
Electrolysis of
pure
11
Aluminium
aluminium oxide
Exam tips
Compounds
molten
or
in
electrolyte.
would
as
it
be
is
and
solution.
oxide
impossible
require
too
soluble
cryolite,
in
solution
much
AlF
Na
considerably.
the
melting
cryolite
used
is
melts
The
alone.
This
cryolite
calcium
or
is
takes
the
very
energy
conduct
alone
high
this
and
electricity
cannot
melting
be
used
point
temperature
special
it
will
aluminium
1000 °C
calcium
or
in
a
when
as
In
an
(2040 °C).
for
containers.
dissolve
uoride
and
so
uoride
mixture
helps
a
long
It
time
Aluminium
mixture
calcium
of
to
reduced
about
be
or
the
aluminium
lowered
energy
5%
reduces
further
than
consumption.
aluminium
oxide
So
this
is
is
the
in
tanks
baking
cathode
is
If
it
not
undergo
you
added
its
will
to
the
to
read
that
aluminium
melting
true,
a
main
purpose
dissolve
were
not
break
up
oxide
point. Although
the
of
dissolved,
into
the
aluminium
ions
it
or
electrolysis.
electrolyte
little
(cells
anthracite
or
‘pots’)
and
lined
pitch.
The
with
carbon.
carbon
lining
This
of
the
siphon
tanks
is
lower
could
causes
books
adding
the
and
to
oxide.
costs
uoride
cryolite
cryolite
uoride.
energy
many
uoride.
place
by
a
maintain
and
containing
made
oxide
However
about
aluminium
Electrolysis
carbon
of
only
6
at
added
point
has
to
water
.
3
This
non-metals
Aluminium
Aluminium
not
molten
metals
nearly
would
oxide
of
(negative
electrode).
The
anodes
(positive
tube
electrodes)
+
are
20
blocks
anodes
into
the
of
carbon
each
cell
as
dipping
about
the
into
400 mm
electrolysis
the
wide.
molten
The
electrolyte.
anodes
can
be
Large
cells
lowered
have
+
further
proceeds.
carbon
The
of
cells
are
40 000 amps
electrolytic
It
linked
takes
a
lot
of
for
a
requires
about
are
series.
required.
reactions
1000 °C
smelters
is
in
and
energy
long
to
period
built
voltage
About
the
rest
keep
of
15 kilowatt
usually
A
the
hours
where
5 V
one-third
is
time.
of
used
to
is
of
the
keep
temperature
The
of
of
a
huge
is
of
of
1 kg
this
of
current
used
electrolyte
electrolyte
For
amounts
and
electricity
the
production
electricity.
large
used
at
in
cathode
(–)
molten
aluminium
molten.
nearly
aluminium
reason,
electricity
molten
aluminium
are
cell
oxide
lining
power
that
cheaply,
station.
some
of
e.g.
The
O
Al
2
hydroelectric
reactions
at
power
.
each
Many
electrode
are
3+
the
cathode
uncertain.
It
their
is
own
An electrolysis cell for the
production of aluminium
possible
3
O
2
aluminium
have
ionises:
Al
At
smelters
cryolite
available
Figure 11.2.2
relatively
aluminium
and
aluminium
→
3–
Al
+
AlO
3
3
ions
accept
electrons
and
are
converted
to
atoms:
3+
+
Al
The
molten
each
cell
aluminium
and
is
which
siphoned
is
3e
→
99.9%
Al
pure
collects
at
the
bottom
Key points
of
off.

At
the
anode
a
possible
reaction
Bauxite
the
3–
4AlO
→
2Al
3
O
2
+
3O
3
+
is
often
simplied
as
a
puried
ore
reaction
in
sodium
precipitating
12e
by
dissolving
the
hydroxide,
impurities
and
2
then
This
is
is:
in
which
oxide
ions
form
oxygen
precipitating
the
puried
by
alumina from
the
solution.
2–
loss
of
electrons:
2O
→
O
+
4e
2

During
anode
the
electrolysis,
which
periodically.
gets
The
the
‘burnt
carbon
oxygen
away ’
and
dioxide
produced
therefore
formed
is
reacts
has
led
with
to
be
away
the
Aluminium
electrolysis
calcium
or
process
aluminium
is
continuous.
uoride
is
Regular
required
to
of
fume
composition.
These
additions
are
additions
necessary
oxide
cryolite
of
in
alumina
and
with
the
of
voltage
aluminium
required
for
oxide
the
falls,
dangerous
electrolysis
electrolysis
anodes
and
cathodes.
constant
because
when
Cryolite
is
added
uorine
gas
is
to
dissolve
the
the
lowers
the
melting
evolved
point
and
using
carbon
alumina. This
concentration
a
aluminium
hoods.

electrolyte
molten
replaced
through
maintain
extracted from
mixture
cells
The
is
carbon
of
the
mixture.
rises.

Large
amounts
needed
to
alumina
keep
of
energy
the
electrolyte
are
cryolite–
molten.
131
11.3
More
about
Learning outcomes
aluminium
Uses of
The
On
completion
should
be
able
of
this
section,
uses
describe
relation
to
uses
its
of
aluminium
physical
and
in
density:
metals.
used
describe
fuselages,
properties
the
impact
of
reect
its
physical
and
chemical
properties:
industry
on
Aluminium
mass
is
there
in
car
lighter
has
one-third
is
and
wooden
in
density
that
energy-saving
bodies
than
lower
of
of
of
the
advantages,
parts
ones.
compared
steel
of
ships.
with
same
e.g.
(as
an
alloy)
Aluminium
High-tension
most
other
volume.
So
for
ladders
electricity
cables
it
is
aircraft
are
between
the
pylons
aluminium
Its
where
much

aluminium
to:
the
chemical
of
you
Low

aluminium
are
usually
made
of
aluminium,
since
it
is
less
dense
and
cheaper
the
than
copper
.
These
cables
have
a
steel
core
because
aluminium
would
environment.
break
under
Good
strength/
(tensile
its
making
its
aircraft,
drinks
than
foils
of
relatively
ratio:
7–11
many
cheap.
The
alone.
strength
to
50
lightweight
materials.
metals
the
of
of
is
aluminium
So
cars
is
the
and
easily
similar
foil
so
advantages
readily
stretching
is
can
useful
for
lorries.
shaped,
price
to
aluminium
aluminium
Aluminium
additional
Aluminium
pure
Alloying
times.
Aluminium
roong
has
10
and
other
it
used
megapascals.
ductility:
and
where
if
strength
ladders
and
cans
packaging
is
tensile
Malleability
weight
mass
strength)
increase
for
own
can
that
machined,
so
is
be
it
cast
it
can
more
used
is
be
used
exible
for
food
non-toxic
and
drawn
and
into
wires.
Good
electrical
electricity
as
copper),
aluminium
its
electrical
good
especially
Good
High
is
mirror
is
It
power
of
and
few
This
is
Aluminium
is
and
not
corroded
Corrosion
surface
it
is
of
metal
alloys
is
car
plane
as
a
why
is
it
used
oxide
is
are
bodies.
It
agent:
is
for
is
are
agent.
used
conductor
of
conductivity
with
its
electrical
very
has
of
low
density,
wiring,
is
well
is
Because
of
the
light
magnetic
its
if
metal
the
not
the
used
in
the
and
chemical
thin
when
oxide
off.
alloying
roong
cans
a
ake
resistance
frames,
drinks
because
So
does
it
elds.
made
reactive.
because
to
materials
food
acidic.
is
is
when
paints,
equipment
layer
of
boilers,
ghting.
resistant
window
of
reectance
corrosion
very
for
(92%
freshly
oxide
corrosion
useful
by
to
the
not
the
make
also
re
navigational
on
parts
silver-coloured
for
resistant
iron,
make
conductivity.
excellent
in
clothing
in
to
thermal
used
forms
Aluminium
reducing
a
the
T
ogether
signicantly
less
to
is
light
aluminium.
used
contents
good
useful
that
oxide
Unlike
than
it
good
reects
Aluminium
aluminium
whose
its
metals
Aluminium
reactive
reducing
industries
air
.
of
affected
aluminium
aluminium
and
containers
not
corrosion.
of
less
corrosion,
Good
to
prevents
Some
and
resistance:
layer
exposed
layer
is
as
59%
cheap.
makes
heat-resistant
Non-magnetic:
not
has
Aluminium
because
the
powdered.
(it
lines.
Aluminium
one
reectors
silver
comparatively
conductivity:
is
Although
and
conductivity
cookware
reflectivity:
nely
gold
overhead
and
reected).
it
in
thermal
cookers
132
conductivity:
copper
,
and
steel
Chapter
Aluminium
industry
Aluminium
very
is
a
useful
and the
metal
and
Did you know?
environment
the
production
of
aluminium
from
The
bauxite
employs
many
thousands
of
people
throughout
the
world.
thousands
making
of
such
window
others
are
different
frames.
But
employed
things
as
producing
in
cars,
industries
electrical
aluminium
which
cables,
has
an
use
aluminium
drinks
price
the
bauxite
metals
cans
the
world
bad
effect
Quarrying
may
which
can
either
be
used
for
and
on
is
an
area
of
natural
beauty,
e.g.
forest
or
hilly
of
a
world
metals
The
quarries
are
unsightly,
noisy
and
can
the
explosives
and
vehicles
used
to
produce
extract
W
aste
rocks
from
the
ore
may
produce
dust
and
of

Breaking

The
waste
This
‘red
Plants

are
The
(furnaces)
kilns
The
of
dust
of
and
unsightly
The
reaction
‘pots’
lifetime.
the
to
the
is
soil
by
transport
spoil
1980s
and
ores
dropped
of
its
exports
badly
were
the
led
with
to
bauxite. The falling
25%
of
the
workforce
ore.
with
this
business
losing
heaps.
jobs.
fumes.
reaction
and
the
remove
and
saturated
present
greenhouse
also
of
of
in
get
sodium
sodium
into
hydroxide.
waterways.
concentrations
the
the
gas,
then
high
with
with
of
sodium
sludge.
water
carbon
from
the
dioxide
hydrated
and
a
certain
produced.
alumina
in
the
gas,
uses
the
carbon
carbon
broken
which
of
may
vast
amounts
greenhouse
producing
(electrolysis
When
produced
used
quantities
formed
greenhouse
into
poisoned
dust
from
which
materials
the
is
electrolysis
therefore
early
alumina
Considerable
The
other
produce
produces
residue
drain
animals
and
Electrolysis

can
ore
precipitated
a
hydroxide
amount

bauxite
products
mud’
alumina

the
produces
and
the
alumina
up
hydroxide
In
fumes
their
Production
very
recession. The
affected Jamaica
75%
connected

a
area.
prices
from
have
countries
agriculture
connected

can
individual
individuals.
was
because
or
ores
cost:
price
land
metal
and
environmental
ore
destroy
market
on
rapidly. This

and
for
there
Quar rying
of
Hundreds
on
of
11
the
gas
of
electricity.
carbon
dioxide
are
electricity.
anodes
with
the
oxygen
also
produces
the
dioxide.
cells)
up
used
or
to
produce
recycling
contain
the
aluminium
walls/
cyanides,
arsenic
and
as
have
electrodes,
and
other
a
nite
dust
is
toxic
compounds.

Fluorine
oxide

in
gas
the
is
produced
cells
Peruorocarbons
between
uorine
powerful
more
decreases.
are
produced
and
greenhouse
the
more
Fluorine
is
during
carbon
a
the
toxic
the
amount
gas
of
which
electrolysis
aluminium
is
very
due
to
reactive.
reaction
electrodes.
Peruorocarbons
it
making
are
very
gases.
Key points

The
properties
cables,
cookware

The
its


of
aluminium
window frames,
and
drinks
properties
corrosion
Quarrying,
of
the
which
toxic
are
aluminium
high
production
affect
The
production
and
other
on
(or
of
car
useful for
and
aeroplane
overhead
bodies,
electricity
mirrors,
cans.
resistance,
particular
make
roong,
the
that
especially
strength
of
alumina
environment
potentially
aluminium
greenhouse
are
mass
and
by
useful
ratio
the
and
are
high
electrolysis
producing
its
dust
low
density,
reectance.
of
alumina
noise
and
have
materials
toxic).
results
in
the
production
of
carbon
dioxide
gases.
133
12
Petroleum
12.
1
The
petroleum
Learning outcomes
Crude oil
Crude
On
completion
of
this
industry
section,
oil
and
(petroleum)
be
able
describe
the
separating
crude

method
the
used
in
components
of
oil
rst
the
from
understand
oil
wells.
fractions.
how fractional
kerosene
separates
crude
16
removed
undergoes
distillation
its
state
the
uses
of
obtained from
and
as
a
mixture
of
hydrocarbons.
compounds
whose
It
relative
contains
alkanes,
molecular
to
by
more
simple
The
Each
than
crude
has
Some
distillation.
oil
is
then
distillation.
fraction
fraction
400.
has
a
of
This
dissolved
‘stripping’
transported
This
to
separates
particular
components
the
with
range
an
the
of
boiling
is
natural
masses
often
oil
oil
done
renery
into
boiling
points
gases
are
near
where
it
different
points
e.g.
the
between
oil
while
the
light
gas- oil
fraction
has
components
with
boiling
component fractions
points

is
aromatic
fractional
160–250 °C,
into
and
to:
range

components
you
cycloalkanes
should
its
raw
250–300 °C.
the fractions
crude
oil
materials for
petrochemical
between
as fuels
the
The
names
12.1.1,
of
which
the
different
also
shows
fractions
where
and
they
their
come
off
uses
are
from
shown
the
in
Figure
distillation
column.
industry.
under
40 °C
bottled
and
bubble
as
gas for
heating
cooking
cap
40–100 °C
gasoline
– fuel for
cars
(petrol)
80–180 °C
naphtha
–
making
chemicals,
especially
plastics
160–250 °C
kerosene
(paraffin)
– fuel for
jet
aircraft
and
heating
250–300 °C
light
gas
oil
– fuels,
including
diesel,
petroleum
for
(crude
lorries,
tractors
oil)
and
cars
300–350 °C
heavy
gas oil
– fuel for
power
stations,
home
furnace
ships
lubricating
lubricants,
and
and
heating
oil
–
waxes
polishes
residue
bitumen
road
sealing
Figure 12.1.1
making
and
roofs
The fractions arising from the distillation of crude oil. The diagram is
simplified and does not show all the reflux pipes in the tower.
134
–
surfaces
Chapter
The
table
boiling
below
point
shows
range
of
the
Fraction
Boiling
approximate
some
of
the
/°C
below
Number of C
of
carbon
atoms
Petroleum
and
fractions.
gas
points
number
12
40
1–4
gasoline
naphtha
kerosene
gas
oil
residue
40–100
80–180
160–250
250–350
above
350
4–8
5–12
10–16
16–25
above
25
atoms
The
naphtha
leads
to
the
chemical
fraction
is
formation
syntheses,
especially
of
e.g.
important.
unsaturated
ethene
for
Further
compounds
making
treatment
which
are
of
this
important
Did you know?
in
poly(ethene).
Crude
for
oil
has
been
thousands
deposits
of
have
known
about
years. Oily
been
written
surface
about
in
Separating the fractions
ancient
The
fed
crude
into
a
oil
is
heated
in
fractionating
containing
bubble
a
furnace
tower
caps
(see
at
about
(column)
Figure
400 °C.
which
12.1.1).
The
contains
These
vapour
about
allow
40
is
then
‘trays’
thorough
this
the
vapour
with
descending
liquid.
In
modern
reneries
the
crude
medical
are
replaced
by
jet
trays
which
are
metal
sheets
with
oil for
lighting
rich
used
and for
purposes. About
1600
years
the Chinese
were
collecting
bubble
crude
caps
tablets. The
mixing
ago,
of
Persian
depressions
oil
using
bamboo
pipes.
in
them.
There
is
cooler
than
a
temperature
gradient
in
the
fractionating
tower
.
The
top
is
Exam tips
with
the
higher
base.
boiling
Near
points
the
base
of
condense.
the
The
tower
,
heavier
lighter
hydrocarbons
hydrocarbons
have
lower
Make
boiling
points
and
so
move
further
up
the
tower
.
As
they
move
up
sure
confused
tower
,
each
hydrocarbon
condenses
at
the
point
where
the
that
temperature
between
tower
falls
just
below
the
boiling
point
of
the
hydrocarbon.
The
the
ascending
vapour
to
come
into
contact
with
the
The
and
separation
theory
behind
occurs
this
is
through
given
in
successive
Section
trays
and
bubble
caps
allow
better
liquid-vapour
in
and
Petroleum
is
of
crude
separation
petroleum
oil.
Petrol
used
as
is
a fuel
equilibria.
10.5.
mixing
petrol.
name for
cars.
It
is
its fraction
The
and
descending
a fraction
liquid
get
words
tower
another
allows
don’t
the
in
petroleum
the
you
the
of
better
name
to
as
remember
it
by
crude
oil
gasoline.
the
components.
After
a
component
condenses
on
a
particular
tray
it
moves
down
to
the
Key points
tray
below.
whose
When
the
temperature
ascending
is
below
the
vapour
reaches
boiling
point
a
of
tray
the
containing
vapour
,
the
liquid
vapour

starts
to
condense.
As
it
condenses,
the
vapour
heats
the
liquid
in
Fractional
separates
tray
and
the
more
volatile
components
in
the
liquid
evaporate.
The
components
pass
up
the
tower
with
the
remaining
process
occurs
in
each
tray,
the
least
volatile
vapour
condensing
most
volatile
evaporating.
The
result
is
that
each
tray
has
a
boiling
components
with
a
narrow
range
of
boiling
The
main fractions
points.
and
with
lower
components
relative
with
molecular
higher
mass
relative
products
molecular
move
mass
up
move
The
under
from
vacuum.
the
crude
Lowering
oil
the
which
pressure
has
not
reduces
passed
the
up
tower
boiling
is
point
distilled
the
components
distil
below
their
decomposition
Section
oil.
petroleum
reduced
residue
is
pressure
distilled
to form
lubricating
oil
and
bitumen
and
Fractional
distillation
separates
temperatures
the
(see
and fuel
fractions.

ensures
kerosene
residue
the
residue
are
gasoline,
the
under
The
gases,
down.

Separating the
obtained
distillation
So
naphtha,
tower
into
ranges
fraction
petroleum
components
distinct
points.
by fractional
containing
components
and

the
the
having
vapour
.
of
This
of
more
fractions
volatile
distillation
the
crude
oil
into fractions
by
a
10.6).
series
which
of
gas-vapour
are
adjusted
temperature
equilibria
as
the
decreases
up
the
column.
135
12.2
More
about
Learning outcomes
petroleum fractions
Cracking
Most
On
completion
of
this
section,
But
should
be
able
describe
the
some
fractions
are
more
we
get
useful
from
than
the
distillation
others
because
of
petroleum
there
is
a
are
greater
useful.
demand
to:
for

of
you
catalytic
cracking
and
them.
from
the
We
use
more
fractional
gasoline
distillation
(petrol)
of
and
diesel
petroleum
(see
than
Figure
can
be
supplied
12.2.1).
reforming
Petroleum

describe
the
impact
of
companies
hydrocarbons,
petroleum
industry
on
solve
this
problem
by
breaking
down
larger
,
less
useful
the
to
smaller
,
more
useful
hydrocarbons.
They
do
this
by
a
the
process
called
cracking.
Cracking
is
the
thermal
decomposition
of
alkanes.
environment.
When
large
alkane
alkene
molecules
alkane
can
molecules
are
undergo
are
formed.
cracking
cracked,
T
wo
of
the
smaller
many
alkane
possible
molecules
ways
that
and
an
are:
50
supply from
refinery
H
C
10
demand from
40
customers
→
C
30
H
10
C
22
→
H
6
dodecane
C
22
+
H
5
C
14
+
H
4
hexane
8
butene
C
12
H
2
+
C
4
H
3
6
%
dodecane
pentane
ethene
propene
20
The
alkanes
formed,
e.g.
C
H
6
are
used
to
make
more
gasoline.
The
14
10
alkenes
seudiser
lio
leuf
leseid
enesorek
ahthpan
sag
/enilosag
yrenfier
0
their
a
used
double
making
as
are
or
chemical
bonds.
many
fuel
in
new
for
They
are
products
making
the
including
H
2
They
starting
ammonia)
C
Figure 12.2.1
synthesis.
→
can
C
6
are
compounds
plastics
also
H
2
very
be
and
reactive
(feedstock)
ethanol.
produced
+
because
by
of
for
Hydrogen
cracking
(used
ethane.
H
4
2
Demand and supply for
ethane
ethene
hydrogen
some petroleum fractions
How
is
cracking
Naphtha
Figure
using
or
gas
12.1.1,
a
catalyst
cracking
is
oil
p.
carried out?
from
134)
in
called
a
fractional
are
the
catalytic
catalytic
distillation
feedstocks.
cracking
cracking .
in
an
Cracking
unit
The
(cat
oil
is
renery
usually
cracker).
vapours
from
This
the
(see
carried
type
gas- oil
out
of
or
cracked
alkanes
and
alkenes
kerosene
aluminium
be
dirty
oxide
continuously
This
catalyst
fractions
frees
the
are
at
passed
through
400–500 °C.
recycled
catalyst
to
the
from
The
cat
any
a
catalyst
catalyst
cracker
carbon
of
is
a
silicon(
ne
through
deposited
a
on
iv)
oxide
powder
and
regenerator
its
surface.
and
has
to
tank.
Modern
reactor
catalysts
include
compounds
called
zeolites
which
are
aluminosilicates.
(cat
cracker)
The
main
products

Renery

A
gas
of
catalytic
containing
cracking
ethene
and
are:
propene.
powdered
catalyst
liquid
with
aromatic
higher
a
high
yield
hydrocarbons.
grade
of
branched-chain
This
is
used
to
alkanes,
make
more
cycloalkanes
petrol
and
(especially
petrol).
catalyst
clean

A
high-boiling
point
residue.
This
is
used
as
fuel
oil
for
ships
and
regenerator
catalyst
home
heating.
long-chained
Long-chain
alkanes
can
also
be
cracked
at
a
high
temperature
(between
alkanes
450
Figure 12.2.2
and
800 °C).
This
type
of
cracking
produces
a
larger
percentage
of
Simplified diagram of a
alkenes
and
is
called
thermal
cracking.
catalytic cracking unit
Reforming
Refor ming
arenes.
136
is
the
conversion
of
alkanes
to
cycloalkanes
or
cycloalkanes
to
Chapter
When
the
gasoline
and
naphtha
fractions
are
passed
over
a
catalyst
above
12
Petroleum
CH
3
500 °C,
the
process
is
straight-chain
alkanes
are
converted
to
ring
compounds.
This
CH
2
called
cyclisation.
See
Figure
12.2.3.
CH
CH
2
The
catalyst
aluminium
is
platinum
oxide.
The
or
Pt
vi)
molybdenum(
or
oxide
catalyses
MoO
the
deposited
3
onto
dehydrogenation
CH
while
CH
2
2
3
the
aluminium
oxide
catalyses
any
rearrangement
of
the
carbon
skeleton.
CH
2
More
modern
diameter
plants
deposited
use
onto
bimetallic
metal
aluminium
clusters
between
1–5 nm
in
oxide.
CH
3
A
catalyst
containing
platinum
and
iridium
atoms
converts
straightCH
chain
alkanes
to
arenes.
CH
CH
2
2
+
H
2
CH
CH
3
CH
2
CH
2
CH
2
CH
2
+
3
4H
2
CH
CH
2
2
CH
2
A
catalyst
from
containing
platinum
methylcyclohexane
to
and
form
rhenium
atoms
remove
hydrogen
methylbenzene.
CH
3
CH
CH
3
+
3H
3
2
+
3H
2
Petroleum
Crude
oil
and
industry
its
rened
and the
products
are
environment
responsible
for
various
types
of
Figure 12.2.3
Cyclisation
pollution.
Oil
Oil
spills
Did you know?
spillages
from
oil
wells
or
tankers
can
kill
wildlife,
especially
sea
birds
The
and
sh.
T
ar
on
the
birds’
feathers
reduces
their
ability
to
y
and
rig
their
insulation
and
ability
to
oat
on
water
.
Even
a
thin
layer
of
worst
oil
sea
results
in
a
large
reduction
of
oxygen
in
the
water
spill from
took
underneath,
of
place
in April
Mexico
die.
Birds,
sh
and
other
animals
also
die
through
ingesting
drilling
the
when
2010
a
in
the
drilling
rig
so
exploded. The
sh
a
on
Gulf
the
oil
reduces
oil
gushed
out for
toxic
three months. Tens
of
thousands
of
components.
sea
Incomplete
combustion
birds
were
jobs.
Incomplete
combustion
of
petroleum
products
results
in
toxic
and sh
taken
So
and
many
large
was
the
being
hydrocarbons.
Section
formed
The
as
latter
well
two
as
can
carbon
particles
contribute
to
and
lost
oil
their
slick
that
carbon
countries
monoxide
died, shermen
ill
in
the Caribbean
were
on
unburnt
photochemical
smog
(see
high
alert
in
case
the
oil
reached
the
region.
14.8).
Lead
Key points
Lead
compounds
agent
in
gasoline
from
the
(petrol)
addition
can
result
of
tetraethyl
in
damage
lead(
to
the
iv)
as
an
nervous
‘antiknock’
system
in

children.
Although
most
gasoline
does
not
now
contain
lead
Cracking
of
fractions
many
people
are
worried
that
the
arenes
put
into
petrol
to
less
useful
oil
compounds,
replace
it
produces
more
useful
are
alkanes
and
alkenes. The
alkanes
poisonous.
are
Acid
used
alkenes
rain
to
to
products
The
in
sulphur
the
are
present
air
to
form
burnt
in
vehicle
in
acid
trace
rain.
amounts
The
engines
in
nitrogen
also
fuels
reacts
oxides
contribute
to
with
formed
acid
rain
oxygen
when
(see
and
fossil
Section
make
make
petrol
a
wide
including
and
the
range
of
plastics.
water
fuels

14.7).
Reforming
chain
converts
hydrocarbons
cycloalkanes
or
straight-
to
arenes.
Plastic

Plastics
made
from
petroleum
products
cause
problems
in
terms
of
Crude
oil
products
disposal
in
the
environment
and
their
effect
on
wildlife
(see
Section
and
its
rened
their
can
be
responsible for
14.11).
various
types
to
accidents
or
transport
of
pollution
during
due
extraction
Metals
Some
of
the
metals
used
as
catalysts
in
the
petroleum
industry
into
the
air
during
catalyst
as
a
result
of
can
combustion
escape
or
of fuels.
change.
137
13
The
13.
1
Ammonia
chemical
Learning outcomes
industry
synthesis
The
Haber
Ammonia
On
completion
of
this
section,
be
able
outline
by
the
Haber
Process.
The
stages
in
this
are:
to:


manufactured
you
process
should
is
Process
the
steps
in
A
mixture
of
nitrogen
(1
volume)
and
hydrogen
(3
volumes)
is
the
compressed.
manufacture
of
ammonia from

its
The
compressed
contains

gases
pass
into
a
converter
(reactor
vessel),
which
elements
describe
the
Haber
the
of
catalyst:
Process

including
trays
The
catalyst
is
iron
(Fe)
or
a
mixture
of
iron
and
III)
iron(
oxide
(the
manufacturing
oxide
gets
reduced
by
the
hydrogen
to
iron).
The
iron
is
porous,
so
conditions
it

understand
the
Haber
Process
has
a
large
of
chemical
for
the
gases
to
react
on.
A
promoter
potassium
hydroxide)
is
added
to
increase
the
equilibrium
effectiveness
and
area
in
(usually
terms
surface
of
the
catalyst.
kinetics.

The
temperature

The
pressure
(but
200 atmospheres
Under
these
converted
to
in
in
the
the
conditions
converter
converter
up
is
to
is
can
usually
range
about
from
common).
15%
of
the
nitrogen
and
N
(g)
+
3H
2

The
here

The
they
(g)
Y
2NH
2
passes
not
(g)
into
condenses.
unreacted
are
are
∆H
–1
=
92 kJ mol
3
mixture
and
hydrogen
ammonia:
Ø

400–450 °C
25–200 atmospheres
an
The
nitrogen
expansion
ammonia
and
is
chamber
.
removed
hydrogen
are
The
as
a
returned
ammonia
cools
liquid.
to
the
converter
so
wasted.
unreacted
N
(g)
2
and
H
(g)
2
recycled
N
(g)
expansion
2
chamber
H
(g)
2
converter
packed
liquid
with
Figure 13.1.1
Exam tips
Different
chemical
synthesis
of
plants for
ammonia
use
the
The
conditions.
If
you
are
an
exam for
the
answer
is:
conditions,
200 atm
materials for the
hydrogen
Haber
is
from
made
the
either
fractional
from
natural
distillation
natural
gas
by
reaction
with
steam
of
450 °C
of
gas
or
crude
by
cracking
oil.
It
can
ethane
also
in
the
presence
of
a
be
made
nickel
catalyst.
pressure,
heat
temperature
Process
the
from
best
An outline of the Haber Process
asked
obtained
in
ammonia
catalyst
slightly
The
different
raw
Fe
and
Fe
(g)
CH
+
+
Ni
O(g) → CO(g)
H
4
+
3H
2
(g)
2
catalyst.
The
carbon
Process
is
monoxide
removed
by
which
can
reaction
CO(g)
+
H
poison
with
O(g)
the
more
→
CO
2
The
nitrogen
distillation
hydrogen.
138
of
for
the
air).
Haber
The
Process
oxygen
catalyst
(g)
+
2
is
from
in
the
Haber
air
is
H
(g)
2
extracted
the
used
steam.
from
the
removed
air
by
(by
fractional
reaction
with
Chapter
The
best
Effect of
conditions for the
Haber
13
in
pressure
The
production
pressure
formed.
Section
fewer
shifts
This
8.5)
is
higher
favoured
because
the
they
plant.
are
by
used
increase
Le
the
in
pressure.
right.
Chatelier ’s
shifts
pressure
Although
not
to
pressure
A
an
towards
according
the
molecules.
on
yield
is
equilibrium
increasing
gaseous
depending
the
the
between
pressures
More
and
above
An
Haber
in
(see
Book
favour
200 atm
is
rst
is
A
lot
lot

At
more
more
1,
is
used,
200 atmospheres
early
to
the
compressors.
pressures
would
withstand
the
the
have
to
extra
reaction
be
spent
vessels
to
are
make
less
them
safe.
strong
A
This
lot
named
Fritz
after
Haber,
the
give
a
catalysts
costs
is
in
a
who
in
improved
testing
order
result
the
process
the
century. The German
Bosch
after
ones. As
power
is
this
twentieth
process
because:
required
chemist
chemist Carl
of
to nd
the
the
thousands
the
of
best
process’s full
Haber–Bosch
Process.
a
money.
higher
money
energy
Process
discovered
name

industry
increase
product
Principle
equilibrium
25
chemical
Did you know?
Process
German
Ammonia
The
Haber
and
Nobel
prizes for
Bosch
were
their
awarded
work.
more
enough
to
pressure.
Effect of temperature
Ammonia
the
production
reaction
is
favoured
decreases
the
For
by
an
value
lower
temperature.
exothermic
of
so
K
reaction
decreases
the
This
an
is
because
increase
yield
of
100
200 °C
in
ainomma
temperature
is
exothermic.
the
p
forward
Le
reaction,
Chatelier ’s
i.e.
the
yield
of
ammonia.
This
is
because
according
to
principle:
80
300 °C
60
fo
decrease

the

energy
in
temperature
reaction
goes
in
the
decreases
direction
the
in
energy
which
of
the
energy
dleiy

surroundings
is
released
%
is
released
in
the
exothermic
reaction.
This
favours
40
400 °C
20
500 °C
the
reactants.
0
50
0
Effect of
A
at
catalyst
which
catalyst
does
the
not
150
100
200
pressure /atmospheres
affect
product
the
yield
(ammonia)
of
is
ammonia
but
does
increase
the
rate
Figure 13.1.2
The yield of ammonia
depends on both the temperature and the
formed.
pressure
The
best
Figure
When
conditions overall
13.1.2
the
shows
how
temperature
the
is
yield
varies
with
temperature
and
pressure.
increased:
Key points

the
rate
of
reaction

the
equilibrium
increases
yield

decreases.
Ammonia
Haber
There
is
a
decreases
which
conict
with
between
increase
increases
with
in
the
between
temperature
increase
in
the
and
best
the
temperature.
equilibrium
best
So
rate
we
use
of
yield,
a
temperature
of
about
420–450 °C
is
used
with
an
iron
catalyst
to
give
a
N
reaction
(g)
+
3H
2
(g)
Y
2NH
2
(g)
3
The
conditions
of
the
Haber
at
reasonable
yield
at
a
are
200 atm,
450 °C
and
fast
catalyst.
rate.

Removing
ammonia
by
condensing
it
also
helps
improve
the
yield.
The
because
removing
equilibrium
to
the
ammonia
right
in
as
favour
a
liquid
of
fewer
shifts
the
position
molecules.
yield
of
ammonia
decreases
This
as
is
the
compromise
Fe
enough
by
Process:
Process
200 atmospheres
manufactured
which

conditions;
is
the
temperature
increases.
of

The
of
rate
of
production
ammonia
temperature

The
increases
conditions
Haber
Process
between
a
and
rate
high
as
increases.
used
are
high
of
a
in
the
compromise
equilibrium
yield
reaction.
139
13.2
The
impact
Learning outcomes
of
The
ammonia
uses of
Ammonia
On
completion
of
this
section,

be
able
describe

describe
uses
and
the
ammonia
85%
of
the
on
a
huge
ammonia
scale
and
produced
has
is
many
used
to
uses
(see
make
Figure
13.2.1).
fertilisers.
to:
the
agriculture
made
you
About
should
is
ammonia
of
ammonia
other
in
industry
impact
industry
of
on
uses
cleaners
including
and
nitric
the
making
household
nylon
dyes
acid
the
making fertiliser
(ammonium
environment.
and
Figure 13.2.1
Apart

The main uses of ammonia
from
making
Making
Nitric
other
acid
nitrogen

As

As

In
a
In

T
o
to
of
make
in
pH
main
of
as
a
textiles
of
ammonia
compounds,
cleans
cleaners
without
on
source
a
of
large
shiny
scale,
nitrogen
fermentation
(especially
for
and
leaving
for
and
dye
acid.
organic
industries.
surfaces
for
nitric
many
‘streaky ’
e.g.
are:
especially
explosives
pharmaceutical
household
the
uses
fertilisers,
the
especially
fermentations
treating
make
Ammonia
refrigerant,
the
the
nitrogen-containing
used
compounds
ovens.
adjust

is
fertilisers,
components
and
salts
nitrate)
such
as
glass
marks.
cooling
ice
microorganisms
rinks.
and
to
mixture.
cotton
and
wool)
to
alter
their
properties.
dyes.
Manufacturing fertilisers
Plant
roots
absorb
plants
convert
When
farmers
not
usually
depleted
into
in
soil,
nitrates.
future
to
When
This
Ammonia
Exam tips
readily
nitrate,
When
writing
equations for
formation
of
ammonia,
remember
ammonium
the
are
are
be
the
from
the
used
soil.
as
So
grow
and
as
such
back
more
nitrates.
needed
taken
of
for
up
as
the
are
should.
manure
soil
minerals
nitrogen,
so
plant
soil
fertilisers
plants
plants
grow
to
and
(mainly
in
ammonium
the
the
compounds
relevant
USA)
such
as
phosphate
but
(aq)
+
HNO
3
as
a
product.
it
evaporates
are
used.
acid.
2NH
(aq)
+
H
3
SO
2
(aq)
SO
2
NO
(aq)
3
ammonium
nitrate
(aq)
+
H
PO
3
(aq)
4
→
(NH
)
4
PO
3
(aq)
4
(aq)
4
ammonia
140
NH
4
acid
→
3
)
4
nitric
4
3NH
(NH
(aq) →
3
e.g.
ammonia
and
ammonium
water
NH
is formed
are
grow.
faster
e.g.
no
modern
available
salts from
that
back
the
not
is
becomes
put
In
are
for
the
the
minerals)
The
growth.
by
years,
they
to
of
yield.
fertiliser
sulphate
are
other
well
essential
provide
crop
form
number
(and
as
ammonium
ammonia
a
nitrogen
other
the
nitrogen
fertilisers
add
a
Over
in
which
the
nitrates
not
to
soil
proteins
soil.
and
used
ammonium
made
to
nitrates
the
crops,
natural
increases
can
from
the
will
quantities
fertilisers
bigger
.
to
Unless
crops
provide
from
their
to
industry,
sufcient
used
nitrates
harvest
returned
agricultural
in
the
nitrogen
phosphoric
acid
ammonium
phosphate
These
Chapter
The
solutions
blown.
the
Hard
soil.
each
are
evaporated
pellets
Fertiliser
other
of
the
and
sprayed
fertiliser
factories
often
are
have
into
a
formed.
several
tower
These
into
which
dissolve
chemical
plants
air
is
slowly
next

nitric
by
Trinidad
to
is
fertilisers
the
Haber
chemical
of
the
in
the
largest
from
largest
nitrate
or
phosphate
fertilisers
phosphorus
plant
are
and
and
is
exporters
3-plant
ammonia
ammonia
fertilisers
from
the
ammonia
and
nitric
acid.
central Trinidad
of
Most
of
Process
and fertiliser factory

exporter
the Caribbean
world’s
of fertilisers. The
acid
industry
Did you know?
one
ammonia
The
in
making:

13
called
NPK
potassium,
fertilisers
all
three
of
because
which
they
are
contain
needed
for
its
at
Savonetta
exports
nearly
in
99%
production.
nitrogen,
healthy
growth.
water
air
Ammonia
and the
phosphate
rock
environment
natural
gas
sulphuric
acid
Eutrophication
Overuse
excess
of
fertilisers
quantities
overgrowth
organisms.
of
of
algae
The
causes
eutrophication .
fertilisers
and
stages
pollute
bacteria
rivers
leading
to
This
and
the
is
process
lakes
death
and
of
by
cause
which
an
aquatic
ammonia
phosphoric
factory
acid factory
are:
potassium

Rainwater
elds
dissolves
into
rivers
fertilisers
and
and
the
solution
runs
off
(leaches)
chloride
from
compound
lakes.
nitric
acid
fertiliser

The
concentration
of
nitrates
and
phosphates
in
the
river
or
factory
lake
factory
increases.

Algae
algal

The
in
the
bloom
dense
water
use
covering
growth
of
these
the
nutrients.
surface
algae
of
blocks
the
They
grow
very
fast
causing
an
water
.
sunlight
ammonium
from
reaching
plants
nitrate
below
factory
the
water
surface.
NPK

These
plants
die
from
lack
of
sunlight.
The
algae
also
die
when
the
fertiliser
nutrients

Bacteria

The

Without
are
feed
bacteria
used
on
up.
the
use
up
dead
the
plants
oxygen
and
algae
dissolved
and
in
multiply
the
rapidly.
water
.
ammonium
oxygen,
sh
and
other
water
animals
die.
nitrate
fertiliser
Other
Smog:
effects of
Ammonia
sulphur
oxides
contribute
Human
to
ammonia
in
from
the
atmosphere
vehicles
and
can
combine
industry
to
with
form
ne
nitrogen
and
particles
which
Figure 13.2.2
A ow chart for making
NPK fertilisers
smog.
health:
Ammonia
itself
can
irritate
the
lungs
and
inhibit
the
Key points
uptake
of
oxygen
Ammonia
salts.
can
These
by
react
exist
as
haemoglobin
by
with
the
acids
small
in
particles
altering
the
pH
atmosphere
(particulates).
to
of
the
form
When
blood.
ammonium
breathed
in

Most
ammonia
is
used
to
make
over
fertilisers.
a
period
of
time,
these
can
cause
bronchitis,
asthma,
coughing
ts
and

‘farmer ’s
Fertilisers
replace
Soil
acidication:
When
ammonia
in
the
atmosphere
reacts
with
the
soil
it
is
converted
to
added
to
nitrogen
the
taken
soil
up
to
by
plants
and
to
increase
crop
+
ions.
NH
the
water
crop
+
in
are
lung’.
NH
4
ions
are
also
present
in
4
yield.
+
fertilisers.
Excess
ions
NH
are
converted
by
bacteria
to
nitrites,
nitrates
4
+
and
ions.
H

+
The
H
ions
make
the
soil
acidic
and
plants
may
not
The
on
able
to
grow
main
impact
of fertilisers
be
the
environment
is
well.
eutrophication.
Changes
to
plant
diversity:
Ammonia
gas
can
settle
on
plant
leaves
and

stems
and
cause
damage
because
of
its
alkalinity
especially
in
Ammonia
can
react
with
acids
in
alpine
the
air
can
be
to form
particulates
which
plants.
damaging
to
health.
141
13.3
Ethanol
Learning outcomes
The
production of
alcoholic
beverages
Fermentation
On
completion
should
be
able
of
this
section,
you
to:
The
drinks
example

explain
the
importance
in
fermentation
and
distillation
exports.
manufacture
of
industr y
is
Jamaica,
the
big
business
r um
in
industr y
many
is
parts
worth
of
the
about
world.
For
45 million
Alcoholic
drinks
include
beer,
wine
and
spirits
such
dollars
as
r um,
in
whisky
the
in
of
and
gin.
Fer mentation
has
been
used
by
humans
for
centuries
alcoholic
to
produce
alcohol.
Fer mentation
is
the
conversion
of
carbohydrates
to
beverages
alcohols

describe
the
fuel
in
uses
of
ethanol
as
the
organic
acids
using
yeast
or
bacteria
in
the
absence
of
air.
a
Almost
and
or
any
vegetable
material
can
be
used
as
starting
materials
as
long
pharmaceutical
as
industry.
they
sugars
acts
contain
such
on
as
sugar
or
glucose.
glucose
or
starch
In
the
sucrose
in
which
can
production
the
absence
be
of
broken
down
alcoholic
of
air
to
to
drinks,
produce
simple
yeast
and
CO
2
ethanol.
From
glucose:
C
H
6
From
sucrose:
C
O
12
H
12
(aq)
→
2C
6
O
22
H
2
(aq)
+
H
11
OH(aq)
+
2CO
5
(g)
2
O(l)
→
4C
2
H
2
air
OH(aq)
+
4CO
5
(g)
2
lock
(CO
can
escape
but
2
air
cannot
fermentation
Figure 13.3.1
Glucose
between
is

T
oo
mixed
and
T
oo
low
a
high
proteins
Exam tips
higher
It
Remember
example
occurs
a
of
in
absence
student
(aerobic
If
oxygen
error
were
respiration),
might
is
oxygen).
to
is
plant
yeast
control
temperature
the
a
will
possibility
temperature
will
have
the
temperatures,
important
to
and
water
(according
keep
of
is
to
material,
water)
air
and
the
alter
the
at
a
temperature
alcoholic
bacterial
cell
structure
proteins
of
of
enzymes
unwanted
out
left
type
will
work
to
to
too
slowly
and
fermentation.
structure
of
catalyse
become
apparatus
to
the
the
yeast
and
reaction.
At
denatured.
prevent:
(it
It

oxidation
of

unwanted
ethanol
to
ethanoic
acid
is
side
reactions
due
to
bacterial
action
in
the
presence
of
air
.
suggest
involves
present
Fermented
used
in
the
drinks
are
generally
fermentation.
For
classied
according
to
the
plant
example:
ethanoic
be formed
of
beverage
important:
incorrect
the
the
cause
will
rather

Beers

Wines
are

Mead
made
from
cereals
and
other
starchy
than
and
ciders
are
made
ethanol.
142
liquor
( yeast,
an
respiration
of
alcoholic fermentation
oxygen.
acid
anaerobic
the
common
that
that fermentation
with
40 °C
T
emperature
increases

in)
vessel
fermentation
sugar,
back
Simple fermentation apparatus
15
required).
get
is
made
from
honey.
from
fruit
juices.
material.
material
Chapter
13
The
chemical
industry
Distillation
There
is
a
limit
fermentation.
than
15%
it
will
fermentation
alcohol
by
the
is
kill
in
the
some
to
characteristic
Other
the
pot
producers
still
use
and
alcohol
In
the
column
a
can
made
by
in
distillation
of
batches
alcohol
and
produced
rises
distilling
alcoholic
than
in
be
content
suitable
higher
the
work
that
alcohol
are
reaches
much
avours
the
Spirits
it
is
ethanol.
rum
its
when
producers
directly
of
when
yeast.
spirits
volume
rum,
amount
because
mixture
content
35–40%
make
to
This
(pot
wines
the
more
the
content.
beers,
fermented
stills).
aroma
or
by
to
Heat
is
compounds
The
e.g.
liquor
to
applied
giving
the
evaporate.
distillation.
See
Section
10.9
for
further
information.
T
wo
important

Rum
from

Whisky
Uses of
Ethanol
The
has
Ethanol

use
cereal
or
sugar
cane
juice.
grains.
of
ethanol
ethanol
of
sugar
is
as
fuel
a
fuel
or
industry
cane
in
residues.
In
a
fuel
the
additive
world.
the
USA,
It
for
is
vehicles.
produced
ethanol
is
Brazil
by
largely
made
(maize).
can
Ethanol
used
fermented
molasses
a fuel
largest
corn
fermented
ethanol
fermentation
from
are:
distilling
from
as
main
the
spirits
either
be
used
containing
for
vehicles
on
4.9%
that
its
own
water
run
on
is
as
a
fuel
produced
ethanol
or
by
mixed
with
gasoline.
distillation.
This
Did you know?
is
only.
It

W
ater
is
removed
by
an
adsorbent,
such
as
a
zeolite
or
starch,
is thought that the word
rst
ethanol
for
mixed
petrol-ethanol
engines
is
came
uses of

Alcoholic

In
the

Ethanol
in

It
is
paints
is
a
beverages
acid

As
an

As
an
language
an Arabic word
in
‘al-ghul’.
above).
to
make
halogenoalkanes,
esters,
ethers,
amines.
(usually
as
methylated
spirits)
as
an
industrial
solvent
adhesives.
commonly
evaporates
(see
industry
and
used
and
English
ethanol
chemical
ethanoic
into the
required.
1543 from
Other
alcohol
if
used
solvent
in
perfume
industry
because
it
rapidly.
antiseptic:
antidote
it
to
is
used
in
poisoning
medical
by
other
wipes
and
alcohols,
antibacterial
e.g.
ethylene
hand
gels.
glycol
poisoning.
Key points

Fermentation

In
order
mixture

to
is

Ethanol
make
can
has
perfume
used
to
produce
alcoholic
drinks
alcoholic
such
as
drinks.
rum
and
whisky,
the fermentation
distilled.
Ethanol from
material
is
the fermentation
be
used
other
as
uses
of
sugar
cane
residues
or
other
plant
a fuel.
including
as
a
solvent,
as
an
antiseptic
and
in
manufacture.
143
13.4
The
impact
Learning outcomes
of
The
ethanol
effect of
Although
On
completion
of
this
section,
be
able
social
describe
impact
the
of
occasions,
in
alcoholic
ethanol
is
beverages
classed
as
a
tends
to
make
psychoactive
people
drug
relax
(one
which
to:
acts

ethanol
body
you
on
should
the
ethanol on the
social
ethanol
and
economic
production
and
we
the
view
small
As
consumption
on
central
things,
amounts
the
nervous
understanding,
we
amount
system
of
may
get
alcohol
a
in
and
and
in
behaviour).
feeling
the
results
of
general
bloodstream
changes
If
we
in
drink
well-being
increases
mood,
alcohol
and
how
in
relaxation.
(measured
as
–3
blood

describe
the
changes
caused
alcohol
content,
BAC,
in
),
g dm
the
ethanol
has
a
progressively
physiological
bad
by
effect
on
us.
The
short
term
effects
are:
alcohol
–3

consumption
BAC
0.5 g dm
:
feeling
of
relaxation,
increased
talkativeness,
impaired
judgement.

describe
the
impact
of
the
–3

ethanol
industry
on
BAC
1.0 g dm
:
difculty
moving
properly,
giddiness,
feeling
of
not
the
being
in
control,
nausea,
vomiting,
symptoms
of
intoxication,
e.g.
environment.
slurred
speech,
aggressive
behaviour
.
–3

BAC
3.0 g dm
:
Not
knowing
what
is
happening
to
oneself,
loss
of
consciousness.
–3
At
blood
alcohol
concentrations
of
above
about
,
1 g dm
ethanol
acts
as
a
Did you know?
depressant,
it
lowers
the
activity
of
particular
parts
of
the
brain.
At
blood
–3
alcohol
The
Latin
saying
‘in
vino
veritas’
blood
wine,
the
truth)
suggests
that
concentrations
to
more
likely
to
tell
the
the
truth
have
had
a
glass
of
wine
leading
to
loss
of
decreases
consciousness
and
the
ow
of
eventually
–3
or
death
at
concentrations
above
4 g dm
effects
of
excessive
consumption
of
alcohol
(alcoholism)
can
two
lead
to
brain,
when
Long-term
they
ethanol
1.4 g dm
people
possible
are
above
(in
to
many
social
and
health
problems.
Although
small
amounts
of
drink!
ethanol
energy,
can
one
be
carcinogenic
body
may
Excessive
metabolised
product
(causes
result
in
alcohol
alcohol
syndrome
various
birth
The
of
the
in
cancer).
liver
the
alcohol
A
and
can
buildup
of
be
is
such
used
as
ethanal
toxic
a
source
and
this
substances
of
is
in
the
cancer
.
consumption
in
body
metabolism
which
the
in
pregnant
child
of
the
women
can
alcoholic
result
mother
in
foetal
can
have
defects.
social
and
economic
impact of
ethanol
Did you know?
These
When
used
as
a
solvent
about

methanol
is
often
added
to
include:
10%
Social
killed
to
‘denature’
the
alcohol
consequences
so
that
as
a
not t for
drinking. This
is
called
methylated
alcoholics,
afford
however,
alcoholic
to
can
drinking
result
in
death.
More
methylated
blindness
Because
manufacturers
of
now
add
methylated
emetics
up
spirits
the
to
of
the
families
driver
under
of
those
the
of
individuals
help
from
the
who
have
an
alcohol
habit
and
who
community.
of
in
hospitals
expensive
required.
liver
In
many
transplants
countries
required
due
to
in
the
world
long-term
consumption
is
increasing
rapidly.
Many
working
hours
are
lost
when
people
do
not
turn
up
for
impact
on
production
work
this,
of
a
‘hangover ’.
This
has
an
economic
methylated
to
there
is
nobody
to
take
their
place.
the
make
people
production
and the
environment
alcohol.
When

It
ethanol
helps
used
144
a
spirits.
Ethanol
vomit
for
of
and
if
spirits
more
treatment
number
because
some
or
drinks,

eventually
injured
judgement
drink.
isolation
require
alcohol
This
individuals
impaired
who
the
resort
the
spirits.

cannot
of
Long-term
may
Some
of
alcohol

mixture
result
it
inuence
is
for
ethanol
as
is
made
conserve
an
by
the
fermentation:
world’s
alternative
fuel.
diminishing
supply
of
crude
oil
as
it
is
Chapter

The
process
is
‘carbon
neutral’.
The
sugar
cane
absorbs
CO
as
13
The
chemical
industry
it
2
grows
and,
although
this
is
CO
returned
to
the
atmosphere
when
2
ethanol
just
burns,
puts
the
into
CO
two
the
processes
are
atmosphere,
in
see
balance.
Section
(Burning
fossil
fuels
14.4.)
Did you know?
2

CO
(a
greenhouse
gas)
is
produced
when
harvesting,
transporting
and
still
and
2
processing
better
and
for
the
the
sugar
cane
and
environment
fractionally
distilling
distilling
than
it.
But
extracting
this
is
petroleum
cheaper
from
the
ground
Ethanol
wood
it.
When
combusted
gases.
an
But
engine
relatively
petrol

The
or
the
as
engine.
less

Food
much
These
Some
can
crop
be
more

The
of
are
destroy

displace

decrease
There
are
of
for
or
low
forests
people
the
level
as
of
cane
or
plant
living
carbon
or
in
get
made from
sawdust
Enzymes
cellulose
have
and
other
which
been
in
produce
sugars
which
can
used
then
to
be
fermented.
with
of
to
for
a
petrol
activity
to
expensive.
cane
make
food,
in
or
diesel
the
smog.
increased
sugar
or
approximately
with
leading
more
feed
The
in
recent
and
biofuels.
food
years.
vegetable
will
If
oils
crop
become
scarcer
.
other
may
plants
areas
of
habitats
these
sinks
so
has
(maize),
ethanol
other
formed
produces
comparison
produces
compared
photochemical
instead
or
also
in
be
greenhouse
amounts
It
particulates
ozone,
areas
the
diesel.
engines
animal
some
than
or
ethanol
corn
food,
and
car
produces
also
straw,
oil.
ethanal
decrease
as
less
and
undergo
biofuels
in
sugar
animal
in
such
such
as
are
ethanol
(petrol)
crude
and
production
grow

Comparing
might
either
grown
destruction
ethanol
biofuels
increased
to
from
aldehydes
expensive
cleared
formed
methanal
plants
engine,
monoxide
generating
used
plants
of
car
gasoline
derived
production
production
on
carbon
diesel
atmosphere
the
amounts
running
combustion
twice
in
in
material.
digest

can
cellulose
(see
lead
to
being
more
countryside
and
lead
land
grown.
to
is
being
The
likely
species’
increased
to:
extinction
areas
Section
14.4)
and
cause
soil
erosion.
methods
two
main

fermentation

hydration
of
ways
of
ethane
producing
CH
=
CH
2
ethanol:
(g)
+
H
2
O(g)
→
CH
2
CH
3
OH(l)
2
Key points
When
have
comparing
to
consider
these
the
methods
and
their
effect
on
the
environment
we
following:

Ethanol
which
Fermentation
Hydration of
is
a
psychoactive
depresses
the
drug
nervous
ethene
system.
Easy
to
set
up
Complex
to
set
up

Drinking
of
Requires low temperatures, e.g. 15–40 °C
Requires
temperature
of
control,
other
natural
catalyst
( yeast)
Requires
phosphoric
acid
ethanol
concentration
so
of
about
15%
distillation
Produces
very
pure
are
plants
alcohol
period
not
being
vomiting
of
and
intoxication.
can
to
excess
lead
to
over
a
death.
required
The
use
rather
materials
nausea,
symptoms
Drinking
long
ethanol

Raw
to feeling
of
catalyst

Produces
leads
300 °C
in
Requires
alcohol
giddiness, feeling
and
yeast
Raw
materials from
distillation
of
ethanol
than
as
gasoline
a fuel
or
diesel
is
of
better for
the
environment
as
petroleum
less CO
is
produced
in
making
2
ethanol
Y
ou
can
see
that
the
energy
requirements
for
the
production
of
ethanol
making
hydration
more
of
ethene
are
(greenhouse
CO
likely
gas)
is
to
be
higher
likely
to
be
than
for
fermentation
by fermentation
than
in
by
petrol
or
diesel.
and
emitted.
2
145
13.5
The
electrolysis
Learning outcomes
The
of
brine
electrolysis of
The diaphragm
On
completion
should
be
able
of
this
section,
to:
describe
the
Brine
involved
in
chemical
is
a
concentrated
from
electrolysis

using
describe the
of
chlorine
diaphragm

the
describe
sodium
diaphragm
economic
production
cell
the
solution
dissolving
of
sodium
rock
salt
in
chloride.
water
.
It
is
The
of
brine
Fig
is
13.5.1
used
to
shows
produced
a
chlorine,
diaphragm
cell
hydrogen
used
to
and
sodium
electrolyse
brine.
cell
advantages
by the
production
of
by

The
cell
is
divided

The
electrolyte

The
anodes

The
cathodes

A
is
into
a
a
series
of
concentrated
cathode
solution
and
of
anode
brine
compartments.
(sodium
chloride).
method
hydroxide
electrolysis
or
of
hydroxide.
brine
aqueous
seawater
processes
electrolysis
the
cell
you
obtained

brine
by
of
are
titanium
are
steel
rods.
grids.
the
porous
diaphragm
separates
the
cathode
and
anode
compartments.
brine.
This
can
is
made
pass
of
a
through
a
mixture
the
asbestos
and
polymers.
W
ater
and
ions
diaphragm.
b
chlorine
X
Ti
of
out
hydrogen out
anode
brine
in
porous
diaphragm
perforated
NaOH/NaCl
solution
electrolyte
diaphragm
Ti
steel
anode
Figure 13.5.1
(+)
cathode
(–)
A diaphragm cell; a The arrangement of the electrodes from above; b A simplified diagram of the cell across X-X in a
The
ions
present
in
the
electrolyte
are:
+

Sodium,
Na

Chloride,

Hydrogen
–
Cl
+
ions,
H
,
from
the
self
ionisation
of
water
–

Hydroxide
ions,
,
OH
from
the
self
ionisation
+
H
O(l)
Y
H
of
water
.
–
(aq)
+
OH
(aq)
2
The
At
electrode
the
reactions
anode
–
Both
Cl
This
is
–
and
OH
–
ions
move
to
the
anode.
Only
Cl
ions
undergo
oxidation.
–
because
chlorine
gas
is
they
are
pumped
in
off
far
greater
from
the
concentration
top
of
the
anode
–
2Cl
than
the
OH
ions.
The
compartment.
–
(aq)
→
Cl
(g)
+
2e
2
At
the
cathode
+
Both
Na
This
is
+
and
H
because
electrochemical
from
the
top
of
+
ions
move
hydrogen
series)
the
is
cathode.
lower
than
cathode
to
in
sodium.
the
Only
H
discharge
The
ions
hydrogen
compartment.
+
2H
(aq)
–
+
2e
→
H
(g)
2
+
The
146
Na
ions
remain
in
the
cathode
undergo
series
compartment.
gas
(and
is
reduction.
the
pumped
off
Chapter
Formation of
sodium
hydroxide
13
The
chemical
industry
Did you know?
+
The
removal
of
H
ions
causes
the
following
equilibrium
to
shift
to
the
A
more
modern
way
of
making
right.
chlorine
+
H
O(l)
Y
H
and
sodium
chloride
is
–
(aq)
+
OH
to
(aq)
use
a
special
ion-permeable
2
membrane
rather
Membrane
cells
than
a
diaphragm.
+
As
more
and
more
H
ions
are
removed,
the
concentration
of
OH
ions
in
produce
a
higher
+
the
cathode
compartment
increases.
So
Na
and
OH
ions,
the
components
concentration
of
sodium
hydroxide
are
present.
The
electrolyte
level
in
the
is
kept
higher
than
in
the
cathode
compartment.
diaphragm
that
the
ow
of
electrolyte
is
towards
the
cathode
compartment
reduces
the
possibility
of
NaOH
moving
to
cathode
H
are
enough,
the
solution
containing
10%
NaOH
and
by
mass
is
run
off
from
the
cathode
compartment.
This
evaporated
more
soluble
The
economic
A
lot
of
and
NaOH
sodium
as
the
a
NaCl
50%
removed
weight/
advantages of
hydroxide
and
by
volume
chlorine
crystallisation
solution
cell
(Castner
cell)
see
‘Did
you
possibility
also
reduced
the
membranes
are
longer
is
than
the
diaphragms.
the
still
cell
manufactured
Exam tip
using
a
You
mercury
is
solution.
a diaphragm
is
leaving
mixing
2
lasting
partially
in
15%
and
NaCl
costs
reduced. The
and Cl
2
concentrated
so
NaCl/NaOH
compartment.
of
When
cells
the
and
mixture
so
hydroxide
This
concentrating
ensures
sodium
anode
than
compartment
of
know?’
do
not
have
to
know
the
box.
details
of
the
mercury
overvoltage. You
Did you know?
on
the
economic
diaphragm
cell
cell
should
or
about
concentrate
advantages
over
the
of
the
mercury
cell.
In the mercury cell method, puried brine flows through the cell in the same
direction as the mercury. Cl
is formed at the Ti anode. At the mercury cathode
2
+
Na
+
ions are discharged in preference to H
ions because of a high overvoltage.
The mercury/ sodium mixture (amalgam) is then sent to an amalgam
Mercury
cell
Diaphragm cell
decomposer, where the sodium reacts with water to form a solution of sodium
hydroxide.
Expensive
titanium
to
cheaper
to
construct
Works at 4.5 
Works
(more expensive
(slightly
to run)
expensive
chlorine
anode
saturated
brine
at
3.8 
less
to
out
run)
brine
Toxic
waste
mercury
mercury
Much
construct
in
sodium
No
must
toxic
mercury
amalgam
be
removed
decomposer
No
asbestos
diaphragm
The
diaphragm
advantages
and
cell
has
several
disadvantages
advantages
are
over
summarised
the
in
mercury
the
cell.
Asbestos
diaphragm
The
needs
table.
to
renewed
often
be
quite
and
asbestos
dust
is
Key points
toxic

The
diaphragm
cell
has Ti
anodes
and
steel
cathodes
and
an
electrolyte
of
Sodium
brine
(concentrated
aqueous
hydroxide

In
the
diaphragm
cell Cl
Sodium
NaCl).
is formed
at
the
anode
and
H
2
at
the
purer
hydroxide
less
cathode.
2
pure
The
solution
from
which
in
the
the
cathode
NaOH
is
compartment
is
a
solution
of
NaOH
and
NaCl
separated.
Needs

The
diaphragm
does
not
cell
contain
works
toxic
at
a
lower
mercury.
voltage
than
the
mercury
cell
and
purity
work
high
brine
Works
to
brine
low
with
of fairly
purity
147
13.6
The
halogen
Learning outcomes
The
The
On
completion
of
this
section,
be
able
importance of the
manufacture
chlor-alkali
describe the industrial importance
of the halogens and their
chlorine
industry
.
materials
solvents
different
compounds

of
industry
chlor-alkali
and
sodium
industry
Both
chlorine
hydroxide
and
sodium
together
is
hydroxide
known
are
as
the
to:
starting

chlor-alkali
you
the
should
and
the
describe the uses of the halogens
end
and
for
aerosols
many
chemical
amongst
chlorine-containing
of
the
last
century
,
chlorine
due
to
solvents
and
plastics.
the
other
compounds
there
increased
Before
processes
things.
was
use
of
this
a
which
There
which
huge
are
was
about
used
growth
chloro - organic
there
produce
are
in
plastics,
15 000
commercially!
the
demand
compounds
always
an
excess
such
of
At
for
as
NaOH
in making bleaches, PC,
produced
by
the
mercury
diaphragm
cells.
The
uses
of
chlorine
and
sodium
halogenoalkanes, solvents,
hydroxide
produced
by
the
chlor-alkali
industry
are
shown
in
Figure
13.6.1.
aerosols, refrigerants and
anaesthetics

The
describe the impact of the chlor-
use
of
decreasing
chlorine
because
environmental
in
of
making
the
problems
solvents
toxicity
(see
of
and
the
halogenoalkanes
products
made
is
now
and
below).
alkali industry on the environment.
Uses of the
a
chloroethene for
halogens
PVC
Fluorine
propene
oxide

T
o
make
uranium

T
o
make
sulphur
hexauoride
for
the
production
of
nuclear
‘fuel’.
solvents
hexauoride,
which
is
an
inert
medium
for
some
inorganics
electrical
e.g.
work.
HCl,

T
o
make
PTFE,
which
is
a
‘non-stick’

T
o
make
hydrouoric

T
o
make
hydrouorocarbons
plastic
for
cooking
pans,
etc.
NaOCl
halogenoalkane
water
acid
for
etching
glass.
purification,
for
anaesthetics.
insecticides,
anaesthetics
Chlorine

b
chemicals
NaCN,
Na
T
o
make
bleaches,
which
often
contain
sodium
chlorate( I)
(sodium
O
2
2
hypochlorite).
paper

T
o
make
vinyl
chloride,
the
monomer
for
the
plastic,
polyvinyl
neutralisation
chloride
(PVC).
soap,
oil

T
o
make
halogenoalkanes

T
o
make
anaesthetics

T
o
make
for
chemical
syntheses.
detergents
refining
rayon
(which
often
have
uorine
in
them
as
well).
and
aerosols
(although
the
production
of
chlorine-containing
acetate fibres
aerosols
other
of
recently
due
to
their
effect
on
the
ozone
layer).
T
o
make
solvents
such
as
trichloroethane
(the
production
of
these
is
purification
also
bauxite
decreasing
layer).
Fig 13.6.1
decreased
uses,

e.g.
has
Some
of
due
to
these
their
toxicity
solvents
are
as
still
well
as
their
used
in
dry
effect
on
the
ozone
cleaning.
Uses of a chlorine and
b sodium hydroxide

T
o
make
refrigerants.
Chlorine-
(chlorouorocarbons)
in
recent
make
years

T
o

Sterilisation
(see
good
Section
insecticides
in
are
and
and
uorine-containing
refrigerants
but
their
use
hydrocarbons
has
declined
14.3).
dyestuffs.
swimming
pools
and
water
treatment
works.
Bromine

Polymers

Making
pesticides,

Making
bromoethene
to
148
containing
combust
bromine
dyes
properly
and
as
in
a
an
atoms
some
are
ame
pharmaceutical
antiknock
car
good
engine
agent
to
(although
retardants.
products.
allow
gasoline
becoming
(petrol)
rarer).
Chapter
Iodine

As
13
The
chemical
industry
Did you know?
a
catalyst
in
the
production
of
ethanoic
acid
by
the
Monsanto
Salt
(sodium
chloride)
was
very
process.
important

As
an
additive
to
the
feed
for
cows,
sheep
and
pigs
(nutrient
to
the
preserving food
Romans for
and
tanning
leather.
supplement).
The

T
o

disinfect
Often
water
added
to
and
table
in
salt
water
(to
treatment.
help
prevent
Romans
soldiers
the
disease
called
salary
goitre).
money
‘salt’
‘connected
chlor-alkali
Chlorine-containing
chlorine
may
Mercury
Mercury
the
can
is
toxic.
and
cell
and
escape
sh
compounds
an
impact
of
and the
as
well
the
as
About
which
mercury
into
the
poison
the
method
of
production
one-third
has
a
of
compounds
air
or
people
water
.
who
the
owing
eat
chlorine
mercury
formed
Even
the
produced
cathode
during
small
the
(see
is
made
Section
operation
amounts
of
of
mercury
using
the
can
cell
kill
‘Minamata
mercury
after
sh.
used
be
in
the
changed
diaphragm
regularly.
of
the
When
it
diaphragm
dries
out,
cell
(see
asbestos
into
the
air
.
Tiny
amounts
of
these
bres
can
cause
the
in
which
breathing
becomes
very
increased
risk
of
lung
Minamata
the
hydroxide
environment
base
and
some
hence
in
evaporation
alter
the
difcult
of
the
the
banned
in
1997
This
litter
may
is
used
industries.
and
and
an
in
(see
was
of
leak
from
process.
water
the
cell
Sodium
or
get
into
poisonous
hydroxide
sufciently
to
cause
is
a
of
the
was
central
nervous
by
people
in
the
was
area
eating
as
tetrachloromethane
solvents,
are
aerosols
and
ozone-destroying
destroy
huge
is
ozone.
poisonous
death
to
(For
and
refrigerants
chemicals.
details
see
were
Other
Section
14.3).
Key points
amounts
not
in
the
biodegradable
Section
recycling
dioxins
the
14.11).
PVC
construction,
so
is
waste
PVC
sometimes
packaging
and
contributes
burnt

to
Chlorine
and
as
a
source
of
energy.
These
and
acidic
hydrogen
chloride
into
used
PC,
to
make
halogenoalkanes,
in
processes
the
is
bleaches,
aerosols,
refrigerants
can
anaesthetics.
atmosphere.
Environmental
the
problems
chlor-alkali
related
industry
emissions
include
efuents
from
the
paper
industry,
which
can
use
chlorine
as
mercury
bleaching
agent,
may
contain
halogenocarbon
compounds
(which
asbestosis
depletion)
and
dioxins
(which
are
very
and
ozone
non-
may
biodegradability
ozone
poisoning,
a
depletion,
cause
In
unknown
reported. This
containing
to
The
by sh.
an
strong

Dioxin
of
mercury.
the
and
put
absorbed
‘epidemic
solvents,
waste
1932. The
there
(PVC)
PVC
landll
controlled
since
layer
they
also
chloride
plastic
other
used
because
halogenoalkanes
Polyvinyl
pH
chlorouorocarbons,
1,1,1-trichloroethene
Bay
water
.
Depletion of the ozone
Many
ethanal
water
cancer
.
occasionally
the
can
organisms
the
leaks
can
from
waste
made
into
in
lung
sh
Sodium
Minamata
which
seeping
of
named
are
caused
hydroxide
of
was
Section
bres
system’
Sodium
(a form
Mercury-containing
a factory
disease
an
town
been
1956
‘asbestosis’
disease’
poisoning)
chemical
is
meaning
with’.
Did you know?
in
to
condition
‘arius’
word
‘sal’
13.5).
from
asbestos
released
latin
of
had
has
the
environment.
Asbestos
13.5)
and
their
salt. The
environment
Japan.
The
buy
gave
waste
Castner
Mercury
have
industry
to
comes from
meaning
The
sometimes
of
PC.
poisonous).
149
13.7
The
production
Learning outcomes
On
completion
should

be
able
describe
of
this
section,

manufacture of
Most
sulphuric
the Contact
manufacture
terms
of
equilibria
acid
is
acid
sulphuric
made
by
the
acid
Contact
Process .
The
raw
materials
you
for
this
process

sulphur
are:
to:
understand
in
sulphuric
The
of
sulphuric
the Contact
the
and
(from
sulphur
deposits
beneath
the
ground,
from
sulphide
Process for
ores
the
of
or
from
hydrogen
sulphide
from
petroleum
or
natural
gas)
acid

air
(from

water
.
the
atmosphere)
Process
chemical
kinetic factors
There
involved.
are
three
conversion
stages
and
in
the
absorption.
sulphur
sulphur
process:
These
sulphur
are
shown
burning,
in
Figure
sulphur
dioxide
13.7.1.
dioxide
98%
H
SO
2
as
+
air
+
2%
4
H
O
2
absorber
recycled
air
beds
water
sulphur
converter
burner
sulphur
trioxide
99.5%
H
SO
2
4
H
SO
2
4
for
Fig 13.7.1
The manufacture of sulphuric acid by the Contact Process
Sulphur
A
spray
burning
of
molten
sulphur
is
burned
S(l)
+
O
in
(g)
a
→
furnace
SO
2
The
gas
sulphur
mixture
dioxide
which
and
Sulphur dioxide
This
a
is
the
reaction
(usually
key
of
out
oxygen
of
by
converter
a
current
(the
in
the
vanadium( V)
the
The
oxide
dioxide
of
the
reaction
catalyst
by
heat
air
.
(g)
burner
contains
about
The
sulphur
converter
is
catalyst,
converted
V
to
dioxide
contains
10%
O
,
on
a
+
O
(g)
Y
2SO
2
is
(g)
is
passed
several
silica
into
layers
support.
In
5
sulphur
trioxide.
Ø
(g)
2
Since
dry
volume.
process.
converter).
sulphur
2SO
of
conversion
reaction
vessel
four)
comes
10%
in
2
2
the
industry
–1
∆H
=
–98 kJ mol
3
exothermic,
exchangers.
the
The
heat
is
removed
percentage
between
conversion
of
each
layer
to
SO
SO
2
is
between
3
96–99.5%.
Did you know?
Absorption
The
idea
Process
was
not
behind
was
discovered
until
demand for
the Contact
much
high
in
later,
quality
1831.
when
and
The
It
the
This
sulphur
ceramic
very
water.
concentrated
sulphuric
acid
that
it
was
is
is
absorbed
tower
The
because
called
sulphur
a
mist
developed
on
trioxide
reacts
with
into
an
a
trioxide
of
98%
absorber.
is
cor rosive
solution
The
not
of
tower
absorbed
sulphuric
sulphuric
is
packed
directly
acid
is
acid.
with
into
for med
water
and
this
does
not
condense
when
ver y
an
The
sulphur
trioxide
scale.
a
150
a
was
easily.
industrial
in
material.
This
sulphur
required,
trioxide
happens
thick
liquid
called
oleum.
dissolves
in
the
98%
sulphuric
acid
to
for m
Chapter
SO
(g)
+
H
3
SO
2
98%
(l)
→
H
4
S
2
sulphuric
acid
O
2
oleum
is
mixed
with
a
little
water
,
The
of
this
acid
is
returned
to
the
Exam tips
98%
sulphuric
acid
is
run
off
an
exam,
absorber
.
The
rest
is
as
concentrated
sulphuric
make
sure
that
to
between
a
question
be
asks for
the
best
conditions
acid.
for
converting
SO
to
SO
2
H
S
2
O
2
(l)
+
H
7
O(l)
→
2H
2
SO
2
which
(l)
to
best
asks for
the
conditions for the Contact
Process
the Contact
the former
high
The
key
reaction
in
the
Contact
Process
pressure
answer
is
low
the
answer
temperature,
and 
to
O
catalyst.
5
latter
is
450 °C,
is:
atmospheric
pressure
and 
O
2
Ø
2SO
(g)
+
O
2
Effect of
Sulphur
When
right.
shifts
however
,
slightly

the
for
At
operate
is
1
Study
extra
very
higher
corrosive
in
either
percentage
the
formed.
at
yield
The
(g)
5
–1
∆H
=
–98 kJ mol
catalyst.
Guide,
of
Section
pressure.
the
there
the
is
is
are
moist
in
Le
the
molecules.
or
at
pressure.
shifts
to
increasing
pressure
This
increase
according
8.5)
to
the
Chatelier ’s
pressure
Most
plants,
temperatures
only
because:
very
increased
use
an
equilibrium
gaseous
reaction
plants
by
of
because
fewer
requirements
pressures,
of
is
atmospheric
of
scale
nature
favoured
position
This
marginally
energy
large
be
the
favour
atmospheric
pressure.
Only

Unit
will
increased
equilibrium
above
The
is
product
(see
the
2SO
3
production
pressure
More
principle
Y
pressure
trioxide
the
(g)
2
one
conditions
Process. The
2
The
and
3
actual
4
in
The
you
reformed.
that
used
industry
(l)
7
distinguish
Some
chemical
oleum
In
When
13
high
yield
needed
to
pressures
additional
without
would
not
produce
above
increasing
compensate
higher
pressure.
atmospheric
problems
because
pressure.
of
the
gases.
Effect of temperature
Sulphur
because
increase
trioxide
the
in
production
reaction
is
is
favoured
exothermic.
temperature
decreases
For
the
by
lower
an
temperature.
exothermic
value
of
so
K
This
reaction
decreases
is
an
the
yield
of
p
the
forward
The
the
reaction,
temperature
reaction
temperature
Effect of
The
the
rate
range
the
in
the
exothermic,
so
that
the
yield
of
sulphur
converter
heat
is
between
exchangers
catalyst
is
within
trioxide.
are
its
450–580 °C.
used
to
working
try
to
Because
decrease
the
range.
catalyst
catalyst
below
is
i.e.
at
does
which
about
not
it
is
370 °C.
affect
the
formed.
It
works
yield
The
best
of
sulphur
vanadium(
at
about
trioxide
V)
oxide
but
does
catalyst
is
increase
Key points
inactive

410 °C.
The
key
Process
The
best
reaction
(g)
+ O
2
the
temperature
is
increased:

The

the
rate
of
reaction

the
equilibrium
conditions
yield
of
no
point
in
yield
trioxide
is
high
at
atmospheric
pressure,
extra
energy
pressurising
the
converter
.
of
rate
is
maintained
in
the
in
the
450 °C,
and
region
at
about
where
450 °C
the
so
catalyst
that
is
there
most
is
a
vanadium(V)
Sulphur
trioxide
oxide.
there
is
absorbed
in
The
sulphuric
acid
rather
than
good
water
reaction
are
pressure
catalyst
98%
temperature
(g)
3
decreases.
sulphur
wasting
2SO
increases

is
Y
used
Process
atmospheric
the
(g)
2
Contact
Since
the Contact
conditions overall
2SO
When
in
is
to
make
oleum.
More
efcient.
sulphuric
add
a
acid
little
is
then
water
to
made
the
by
oleum.
151
13.8
The
importance
Learning outcomes
Sulphur
About
On
completion
of
this
section,
be
able
0.1%
in
describe
the
importance
industrial
of
used
compounds
of
The
describe
dioxide
the
use
in food
of

describe
acid
the
sulphuric
the
salt
preservation
compounds of
Earth’s
crust
consists
of
sulphur
domes
in
the
USA
and
sulphur
.
Mexico
and
It
is
found
associated
as
the
with
of
the
the
various
production
sulphur
other
parts
10%
is
is
of
rst
used
of
sulphuric
burnt
to
processes
Europe.
to
make
and
in
About
acid.
make
90%
In
of
the
for
sulphur
production
sulphur
chemicals
the
other
dioxide
of
(see
agriculture,
mined
is
sulphuric
Section
13.7).
dyestuffs,
in
vulcanisation.
and
Vulcanisation:
manufacture
impact
acid
in
woodpulping
sulphur

sulphuric
in
acid,
sulphur

of
some
acid
to:
minerals

and
sulphuric
you
element
should
of
rubber
to
‘accelerator ’
the
industry.


In
make
is
powder:
as
and
Carbon
manufacture
tyre
also
Sulphur
vines
the
the
harder
.
added
This
is
to
of
The
speed
used
as
a
tyres,
rubber
up
the
sulphur
is
becomes
added
less
to
the
sticky.
An
process.
fungicide
for
dusting
on
plants
such
strawberries.
disulphide:
This
used
for
making
the
polymers
rayon
and
cellophane.

Pharmaceuticals:
e.g.

Some
drugs
and
medicines
are
sulphur
compounds,
sulphonamides.
Organic
sulphur
compounds:
Some
dyes
and
agrochemicals
contain
sulphur
.
Exam tips
When
answering
questions
about
The
the
uses
of
the
concentrate
compounds,
on
a few
important
ones
so
a
detail,
of
that
uses of
the
most
you
can
Sulphuric
more
e.g.
rather
acid
is
burnt
the
make
drugs’,
answer
a
‘sulphur
better
is
used
answer
‘sulphur
make
compounds
sulphonamide
are
drugs’.
of
air
to
produce
sulphuric
acid
by
the
the
sulphur
Contact
dioxide
for
the
to
used
preservation
to
Sulphur
any
as
dioxide
bacteria
wine
and
general,
such
it
as
which
is
dried
is
may
used
present.
be
The
to
preserve
Sulphur
fruits
sulphites
packaged
released.
such
such
meats
caused
sulphur
by
as
as
and
food
dioxide
sodium
bacterial
be
in
drinks.
added
order
sulphite,
ready-made
dioxide
and
can
apricots
the
it
is
The
+
wood
dioxide
pulp.
It
damaged
Other
is
2
agent.
is
2H
by
acid
agent,
drink
(aq)
used
as
especially
stronger
(in
killing
them.
added
to
such
In
foods
conditions,
sulphur
dioxide
(g)
O(l)
is
→
SO
+
H
a
2
food)
sulphur
reacting
action of
is
are
acidic
by
drinks
dioxide
with
the
also
acts
as
an
antioxidant,
air
.
sulphur dioxide
bleach
useful
during
for
bleaches
the
bleaching
such
as
manufacture
silk,
wool
of
and
paper
straw
from
which
chlorine.
uses
Sulphur
SO
and
preserve
2
ion
reducing
bleaching
Sulphur
are
a
food
this
to
+
(aq)
sulphite
preventing
to
In
does
bacteria.
3
Because
It
directly
which
meals.
fermentation,
kills
2–
SO
152
required
Process.
would
Food
be
in
than
manufacture
given
manufacture
give
Sulphur
bit
sulphur dioxide
just
dioxide
used
as
was
an
formerly
inert
used
solvent.
as
a
Sulphur
refrigerant.
dioxide
gas
In
is
chemistry
a
good
liquid
reducing
Chapter
The
uses of
sulphuric
acid
13
paints
The
chemical
plastics
and
industry
phosphate
fertilisers
Figure
13.8.1
Among

to
shows
other
make
the
things,
main
uses
sulphuric
phosphoric
acid.
of
acid
sulphuric
is
acid.
used:
Sulphuric
acid
is
added
to
calcium
other
uorophosphate
rocks
to
produce
the
acid.
Phosphoric
acid
is
used
to
cleaning
fibres
make
phosphate
metals
fertilisers
other
soaps

to
make
ammonium
fertilisers
sulphate
which
is
a
and
uses
fertiliser
detergents

as
a
cleaning
agent
for
metal

as
the

as
a

to
make
detergents.

to
make
dyes

to
make
corrosion-resistant
surfaces
Figure 13.8.1
electrolyte
catalyst
in
in
lead/acid
various
and
car
chemical
Many
of
processes
these
are
sulphonates
Did you know?
paints
concrete.
Jābir
ibn
called
The
impact of the
sulphuric
acid
industry
general
the
are

sulphuric
sulphur
a
In
the
the

(or
acid
which
are
Sulphuric
acid
can
in
result
The
Acid
eyes
The
can
acid
of
acid
hydrogen
sulphide.
used
not
be
acid
environment
to
make
allowed
rain
from
causing
are
(see
escape
Section
various
death
of
toxic
sulphuric
to
about
is
sometimes
discovering
1200
years
is
sulphuric
ago.
However
,
sulphuric
cause
lakes
dioxide
minerals
as
acid,
into
14.7).
industrial
animals
and
sulphur
by
can
cause
acidication
of
soils.
This
leaching.
dioxide
in
the
atmosphere
can
lead
to
irritation
throat.
in
a
metals
sulphuric
acid
the
re
hydrogen
industry
the
and
toxic.
with
who
of Chemistry’
sensitive.
present
of
into
rivers
not
of
must
and
is
as
processes)
toxic
sulphur
of
present
contact
Since
of
and
aerosols
acid
and
loss
presence
the
escaping
acidify
such
trioxide
are
corrosive,
production
other
they
liberation

Process
as
dioxide

the
atmosphere
may
although
compounds
sulphur
Sulphuric
of
in
sulphur
or
plants

used
itself,
dioxide
processes

of
Contact
sulphur

oxides
number
acid
Hayyān,
‘the father
credited
acid
In
The uses of sulphuric acid
batteries
is
with
gas
a
sulphuric
which
used
contributes
atmosphere
which
include
gaseous
sulphur
hazard.
to
could
make
indirectly
acid
spill
explode
phosphate
to
can
and
result
cause
fertilisers,
eutrophication
(see
in
the
res.
the
sulphuric
Section
13.2).
Key points

Sulphur
of

is
burnt
sulphuric
Other
uses
to
make
sulphur
dioxide,
which
is
used
in
the
production
acid.
of
sulphur
are
vulcanisation
of
rubber,
making
polymers
and
in
agriculture.

Sulphur
dioxide
manufacture

The
main

Sulphuric
is
and
use
of
acid
is
used
as
a
as
sulphuric
used
a food
preservative,
in
sulphuric
acid
bleach.
to
acid
make
is
in
making fertilisers.
detergents
and
dyes
and for
cleaning
metal
surfaces.

The
impact
formation
of
of
the
acid
sulphuric
acid
industry
on
the
environment
is
largely
the
rain.
153
Revision
Answers to
1
all
List four factors
industrial
2
revision questions
a
Give
b
i
chemical
the
from
name
which
What
that
ii
that
is
determine
name
some
how
By
writing
dioxide
d
Why
its
e
is
is
is
an
7
List
two
bauxite
ores
8
its
of
red
in
i
the
impurity
showing
the
b
i
added
to
show
is
the
occur
at
the
electrolysis
f
Why
must
g
Why
is
the
cathode
of
the
and
anode
be
electrolytic
bauxite
the
plants
in
two
anode
aluminium
the
i
reactions
during
during
that
out
a
List
three
effects
the
by
Explain
iv
Why
as
aluminium
industry
of
the
What
that
are
the
allow
properties
aluminium
(physical
to
be
used
or
are
the
in
stated
to
a
List
make
the
b
Explain
of
i
overhead
ii
food
iii
cooking
iv
fire fighter
ammonia.
Include
required for
under
the
a
process
balanced
the
a
which
using
the
principle
pressure
and
process
ammonia
Haber
state
yield
is
Process.
the
temperature
maximum
answer
in
c
conditions
c
i
not
ii
of
that
ammonia
above.
used for
exactly
dictated
in
four
electricity
uses
by
in
the
line
process,
with
Le Chatelier’s
c
the
principle,
ii?
10
a
pots
is
crude
oil
the
process
b
name
of
the
process
by
eutrophication
in
and
the
role
contributing
to
Write
a
balanced
What
is
separated
into
its
of
name
equation
glucose
of
the
to
showing
produce
enzyme
process
in
a
used
the
ethanol.
in
the
above?
which
c
is
of
process.
fermentation
clothing
the
ammonia.
cables
packaging
What
of
ammonium-based fertilisers
fermentation
i
Process
chemical)
this
a
Haber
environment.
following:
4
the
has
9
b
on
process.
your
stated
as
on
nitrogen
produce
this
iii
the Caribbean?
that
has
answer.
industrially
conditions
3
industry
required for
methane?
your
Le Chatelier’s
would
the
carried
of
conditions
conditions
periodically?
not
the
the
Using
using
replaced
equation for
hydrogen
in
produced
oxide.
process
is
State
ii
equations for
petroleum
obtained?
c
electrolysis?
Write
How
silicon
oxide
the
production
the
equation
bauxite.
aluminium
balanced
obtained from
is
how
a
How
ii
equations,
that
environment.
colour?
above
effects
Write
bauxite.
the
three
a
extracted.
impurity
the
balanced
of
and formula
removed from
cryolite
of
the
bauxite
the
removed from
c
location
accompanying CD.
plant.
aluminium
gives
be found on the
the
and formulae
the
Describe
can
questions
Theoretically,
higher
temperatures
would
components
increase
the
rate
of
production
of
ethanol
using
called?
this
ii
Describe
the
principles
upon
which
process,
method
mentioned
in
a
lower
temperatures
are
the
chosen. Give
separating
however
i
above
a
reason for
this.
is
d
State
two
other
conditions
(besides
the
based.
temperature
b
List four fractions
of
crude
oil
and
state
the
a
i
Define
ii
Why
‘cracking’
do
process
b
presence
of
the
enzyme)
are
required for
the fermentation
process.
each.
e
5
the
uses
that
of
and
An
alkane
and
petroleum
of
state
the
companies
two
types.
carry
out
of
the
of
12
carbon
cracking
hydrocarbon
with
to
10
produce
carbon
a
process
ethanol
by
which
produced
the
concentration
by fermentation
is
f
List
three
a
Why
b
State
uses
of
ethanol.
atoms
11
undergoes
the
the
increased.
cracking?
consisting
Name
is
ethanol
classified
as
a
drug?
saturated
atoms
and
three
short-term
effects
of
ethanol
on
the
an
body.
unsaturated
hydrocarbon.
i
equation
c
Write
an
to
show
this
State
two
long-term
effects
of
ethanol
on
the
reaction.
body.
ii
Name
the
unsaturated
hydrocarbon formed.
d
6
a
What
b
Why
is
is
reforming?
reforming
petroleum
154
a
State
of
useful
industry?
process
in
the
one
social
ethanol.
and
one
economic
consequence
Chapters
12
Write
the
the
equations for
anode
and
production
13
a
Why
is
of
the
cathode
in
reactions
the
chlorine from
the
industry
11–13
Aluminium,
taking
diaphragm
place
cell for
petroleum
and
the
chemical
industry
–
revision
questions
at
the
brine.
called
the
chloro-alkali
industry?
b
State
c
Why
does
have
to
d
Under
of
14
four
Sodium
The
iii
Polyvinyl
Dioxins
three
of
equations for
a
Explain
c
State
a
List
two
b
List
four
c
State
on
stages
used
the
the
diaphragm
basis?
discuss
on
the
the
impact
environment:
principle
of
sulphur
answer
uses
uses
the
temperature
yield
of
in
industrial
acid. Write
balanced
stage.
conditions
two
products.
chloride
and
your
the
chlorine
sulphuric
maximum
b
in
regular
headings,
of
Le Chatelier’s
pressure
used
a
its
layer
each
production
16
on
or
hydroxide
ozone
iv
of
asbestos
production
i
Using
chlorine
the following
the
the
of
changed
ii
State
a
the
be
preparation
15
uses
in
of
would
produce
above.
the
industrial
dioxide.
sulphuric
of
conditions
trioxide.
sulphur
effects
that
the
trioxide.
used for
sulphur
of
a
state
the
acid.
sulphuric
acid
industry
environment.
155
14
Chemistry
and
14.
1
The
cycle
water
Learning outcomes
The
On
On
completion
of
this
section,
the
be
able
describe
water

the
importance
of
the
cycle
describe
purication
cycle
planet,
ice
water
caps
only
or
stays
when
in
the
stored
in
same
place
aquifers
when
(huge
frozen
in
natural
reservoirs
surface
of
and
a
methods for
absorbed
in
the
water
into
porous
atmosphere
cycle
(Figure
is
rocks).
The
constantly
water
on
evaporating
the
and
the
condensing
to
form
14.1.1).
energy
wind
carries
clouds
water falls
as
(desalination, fractional
rain,
distillation,
or
explain
the
dissolved
importance
oxygen
to
hail
transpiration
electrodialysis)
and

Earth
purifying
solar
water
of
to:
water

water
you
permanent
should
and
water
our
environment
snow
respiration
of
aquatic
clouds
life.
water
into
evaporation from
aquifers
sea,
land,
lakes
water
and
in
rivers
rivers
returns
to
sea
wells
water
waste
in
Fig 14.1.1
Fresh

The
water

When
water
The
In
is
into
rivers
this
home
kept
get
carried
or
and
lakes
onto
nds
the
seas,
by
colder
larger
sea
and
from
condenses
falling
way,
is
reaches
and
the
water
and

air
cools
droplets
back

purified for
human
works
evaporates
vapour
this
vapour
The
sewage
treated
use
or
in
industry
The water cycle


water
its
of
or
falls
back
into
in
the
sea
seas,
air
,
water
surface.
the
to
Some
the
through
the
Earth’s
colder
of
snow.
on
soil.
the
or
droplets
drains
water
the
across
rain
some
land
way
amount
as
and
masses
tiny
fall
and
the
winds
land
to
lakes
water
form
of
the
clouds.
water
falls
land.
the
to
soil
start
the
into
the
streams
cycle
atmosphere
again.
and
land
constant.
Did you know?
Dissolved oxygen
If
the
is
too
total
dissolved
gases
in
Aquatic
high sh
can
get
‘gas
affects
is
rather
deep
like
sea
of
and
can
block
the
blood
this
through
eventually
gas form
in
life
such
as
sh,
the
oxygen
crabs
(DO)
and
for
plankton
respiration.
(tiny
If
animals
there
is
not
in
the
sea)
sufcient
‘bends’
dissolved
in
the
water
,
aquatic
animals
will
die.
Oxygen
gets
into
divers.
rivers,
Bubbles
life
dissolved
oxygen
which
aquatic
bubble
need
disease’. This
and
water
the
and
the
sea
by:
blood
the flow
vessels.
lakes
of
It
blood
can

diffusion
through

diffusion
from
be fatal.
over
waterfalls
the
water
bubbles
or
from
of
surface
air
from
trapped
in
photosynthesis
the
air
fast-owing
of
aquatic
water
as
it
goes
plants.
–3
At
20 °C
amount

156
The
and
of
at
DO
DO
atmospheric
in
water
decreases
pressure
depends
as
on
there
several
temperature
is
about
9.5 mg dm
DO.
The
factors:
increases
and
as
pressure
decreases.
Chapter

Salt
water

Degree
of
has
less
DO
agitation
of
than
the
freshwater
.
water
14
Chemistry
owing
Stagnant
water
has
less
The
and Tobago
of
bacteria
and
water
plants
removing
oxygen
from
in
eutrophication
(see
Section
in
amount
example
survive
of
sh
DO
such
than
huge
needed
as
small
trout
by
an
and
organism
salmon
invertebrates.
The
depends
need
plant
and
it
is
one
the Americas. The
of
plant
the
is
13.2).
located
The
a
the
largest
e.g.
has
water
.
number
water
environment
DO
desalination

the
Did you know?
surface.
Trinidad
than
and
on
relatively
minimum
DO
the
species.
higher
level
For
amounts
to
support
the
to
near
water
purposes
an
can
as
industrial
be
well
used for
as for
estate
so
industrial
drinking
a
water. Water
is
taken
in from
the
–3
healthy
sh
population
is
.
4–5 mg dm
When
the
DO
levels
fall
below
this,
sea
and
has
to
be
pre-treated
–3
aquatic
life
is
put
under
stress.
At
DO
below
sh
1–2 mg dm
will
die.
extensively
is
Purifying
Pure
water
brackish
for
of
or
(slightly
salts
fresh
seawater
drinking
water
removal
where
water
from
water
is
the
in
this
water
is
can
be
expensive
countries
where
over
of
one
of
is
60%
end
of
all
a
it
water
,
large
compartments
from
a
from
seawater
important
e.g.
having
those
in
low
by
or
Desalination
especially
of
are
warmed.
each
of
by
fractional
energy.
cheap.
water
exchangers)
At
obtained
desalination .
seawater
lot
supplies
and
(heat
lower
.
is
be
is
before
there
which
is
desalination. This
a
has
sedimentation
lot
to
of
be
silt
in
the
removed
and ltration.
the
countries
rainfall.
and ash distillation
desalinated
tank
it
by
supply,
requires
energy
can
water)
short
obtained
as
the
successively
industry
salty
Fractional distillation
Pure
because
in
It
the
stages,
is
distillation
most
suited
distillation
world.
then
where
these
Flash
the
is
This
Seawater
pumped
of
produces
is
fed
through
pressure
some
and
the
but
to
a
in
at
series
temperature
seawater
turns
seawater
to
steam
and
condenses
again,
so
forming
pure
water
(see
Figure
14.1.2).
Electrodialysis
+
Electrodialysis
is
used
to
transport
the
ions
in
salt
purified
(Na
and
Cl
)
from
one
water
solution
of
a
a
to
another
voltage.
positively
The
through
ions
Cl
charged
an
ion-exchange
move
towards
anion-exchange
the
membrane
anode.
membrane
under
These
but
are
ions
the
pass
prevented
through
waste
migration
to
the
anode
by
the
negatively
charged
water
from
Fig 14.1.2
further
out
inuence
Simplied diagram of a ash
cation-exchange
distillation unit (* shows where the water
+
membrane.
The
ions
Na
move
to
the
cathode
but
are
prevented
migrating
condenses)
further
one
Ion
by
part
an
of
anion-exchange
the
cell
leaving
membrane.
the
other
part
So
the
ions
depleted
in
are
concentrated
in
ions.
exchange
Ion-exchange
columns
have
been
used
in
commercial
and
household
Key points
water
an
purication
ion
on
the
units
resin
for
swaps
many
with
years.
an
ion
These
in
are
solution.
based
In
on
order
the
to
idea
that
remove

sodium
and
chloride
ions
from
water
a
series
of
three
columns
is
The
amount
atmosphere,
one
which
acts
as
the
desalination
column
and
another
two
which
maintain
a
specic
balance
of
anions
and
is

Reverse osmosis
kept
a
region
forced
of
low
membrane,
solution
by
gets
from
a
solute
region
high
concentration
applying
more
of
a
pressure
concentrated
solute
as
concentration
through
on
the
the
a
high
water
in
the
and
constant
by
the
the
cycle.
Dissolved
aquatic
is
seas
cations.
water
W
ater
water
the
serve
land
to
of
used,
selectively
(salt
from
side.

The
is
essential for
to
permeable
concentration
passes
solution)
oxygen
life.
salt
Temperature,
bacteria
it.
oxygen

Water
all
salt
affect
dissolved
can
be
and
the
in
number
amount
of
of
water.
desalinated
by
Freeze desalination
distillation,
When
salty
water
freezes,
the
ice
separates
leaving
a
solution
with
a
exchange,
concentration
of
salts.
The
ice
is
taken
from
the
solution
and
repeating
this
process
several
times,
ice
free
of
salts
is
ion
reverse osmosis
and
re-melted.
freeze
By
electrodialysis,
high
desalination.
formed.
157
14.2
Water
pollution
Learning outcomes
The
sources of
W
ater
On
completion
of
this
section,
pollution
be
able
describe
the
pollution
heavy
sources
(nitrates,
metals
cyanide,
water
phosphates,
(lead
trace
of
and
metals,
mercury),
rivers
them.
end
herbicides,
petroleum
suspended
particles)
describe
experiments
selected
pollutants
sites.
lead
and,
in
the
of
wastes
chemical
are
often
or
biological
discharged
often
also
Material
pollutants
treated,
contains
may
also
still
have
synthetic
leach
into
toxic
into
substances
seas
detergents
rivers
in
which
from
waste
may
disposal
include:
from
the
leaching
of
fertilisers
(see
Section
13.2).
residues,
Phosphates:
to
test for
phosphates
from
from
the
leaching
of
fertilisers
and
sewage
disposal
including
detergents.
(nitrates,
ions,
metals:
e.g.
mercury
from
the
chlor-alkali
industry,
lead
from
old
cyanide)
pipes
the
effect
of
and
from
anti-knock
agents
from
petrol,
cadmium
from
the
aquatic
water
batteries.
from
metal
extraction
industries,
e.g.
silver
,
gold,
the
iron
and
environment
steel
describe
and
pollutants
Cyanides:
industry
and
from
the
discharge
of
material
from
the
preparation
of
treatment.
organic
Other
chemicals.
metals:
leaching
into
e.g.
through
Pesticides
and
paints
from
reaching
plant
of
T
oxicity
levels
of
in
are
washes
extraction,
from
these
from
trace
elements
by
industry.
crops
and
leaches
them
in
the
water
of
clay
sites,
the
fertiliser
and
other
quarries
and
material
storm
such
as
sewers.
environment
can
may
disturbs
inorganic
mercury
reduce
inhibit
food
the
amount
of
photosynthesis
chains
run- off
Phosphates
waste.
and
the
world.
with
(see
from
and
in
the
even
lead
water
.
Section
sewage
sunlight
and
and
13.2)
can
lead
detergents
to
also
consequent
effect
on
spillages.
If
effect
Section
they
on
of
result
leak
in
food
into
wildlife,
12.2).
water
Diseases
the
metals
are
concentrations
poisonous,
can
reach
e.g.
high
water
.
herbicides
can
heavy
Their
e.g.
is
responsible
such
contaminated
water
harmful
of
contamination
in
Many
lead.
bodies
in
(see
particles
This
through
pesticides
presence
Oil
12.2).
aquatic
organisms.
associated
Many
Small
This
enclosed
Microbial
sickness

clay
discharges
eutrophication.
cadmium,

rain
Section
plants.
death.
death
cause

from
from
construction
solids
water
Eutrophication
the

or
and the
Suspended
to
(See
particles:
washed
Pollutants

soil
herbicides:
residues:
Suspended

aluminium
the
rivers.
Petroleum
158
sewage
sea.
electroplating

introduction
turbidity
describe
on
the
Industrial
although
Common
water

to
water
.
pesticides,
Heavy
phosphates,
and
the
Domestic
up
Nitrates:

into
to:
and

due
pollution
you
materials
should
is
water
as
cholera,
for
80%
of
typhoid
all
and
the
malaria
water
.
are
the
halogenated
death
chain)
water
,
seals
as
of
well
as
petroleum
can
be
hydrocarbons.
invertebrates
infertility
residues
blinded
and
(and
in
Their
its
birds.
may
birds
have
may
a
die
Chapter
Testing for
selected
14
Chemistry
and
the
environment
pollutants
Nitrates
Add
aqueous
zinc
powder
ammonia
sodium
or
gas
hydroxide
aluminium
is
released
to
the
powder
(see
Unit
(or
1
suspected
nitrate
Devarda’s
alloy).
Study
Guide ,
and
On
Section
then
either
warming,
14.3).
Phosphates
Acidify
with
molybdate.
gently
Lead
concentrated
The
nitric
formation
indicates
that
a
of
a
acid
and
bright
phosphate
is
add
yellow
a
little
ammonium
precipitate
on
warming
present.
ions
Did you know?
–3
Add
1 mol dm
redissolves
hydrochloric
in
hot
water
acid.
The
indicates
that
presence
lead
is
of
a
white
present.
A
precipitate
that
conrmatory
test
Mangroves
is
to
add
aqueous
potassium
iodide
to
the
acidied
water
.
A
bright
kinds
precipitate
indicates
the
presence
of
are
areas
where
various
yellow
of
trees
grow
in
several feet
lead.
of
water
tropical
along
and
the
coast
subtropical
in
some
areas.
In
Cyanide
mangrove
Add
If
a
iron( ii)
deep
sulphate
blue
to
complex
the
ion
solution
is
then
formed,
acidify
cyanide
with
ions
hydrochloric
are
acid.
present.
is
needed
some
swamps
in
the
high
water
young sh from
preserve
the
turbidity
to
protect
predators
and
ecosystem.
Turbidity
T
urbidity
simplest
through
use
a
a
to
to
the
column
using
greater
scattering
a
the
and
cloudiness
measure
to
detector
the
the
measure
number
of
turbidity
containing
nephelometer
particles
The
refers
way
on
of
greater
to
the
under
light
same
suspended
the
test.
scattered
side
of
the
particles,
detector
matter
measure
liquid
the
the
suspended
is
A
by
a
liquid.
as
The
transmitted
better
the
tube
the
in
light
method
is
to
suspended
the
greater
light
is
beam.
the
reading.
Water treatment
W
ater
this
has
to
process
be
to
treated
purify
to
make
dirty
it
water
safe
for
drinking.
The
main
steps
in
Key points
are:


Screening:

Aeration:
Removes
large
oating
Common
include
Removes
volatile
substances
such
as
hydrogen
sulphide
nitrates,
metals,
Flocculation
and
together
sedimentation:
and
are
then
The
water
removed
after
is
agitated.
Small
particles
Filtration:
Removes
nely
suspended
particles
from
the
Coagulation:
There
ne
Iron
sulphate
suspended
or
particles
aluminium
clump
sulphate
are
Disinfection:
Chlorine
is
added
to
specic
chemical
added
to
phosphates,
tests
lead
help
and
cyanide.
together
.


are
nitrates,
ions
very
particles.
water
.
for

pesticides,
and
settling.


phosphates,
cyanide,
residues
suspended
clump
water
oils.
petroleum

in
and
heavy
volatile
pollutants
objects.
kill
bacteria
and
Turbidity
is
measured
by
the
other
ability
of
a
suspension
to
scatter
microorganisms.
light.

Adsorption:
Activated
charcoal
is
used
to
adsorb
organic
chemicals

which
might
give
a
bad
odour
and
taste
to
the
Water
is
treated
processes

Oxidation:
Undesirable
substances,
e.g.
are
oxidised
with
ozone
to
form
less
harmful
Desalination:
(see
Section
the
of
aeration, ltration,
disinfection
and
products.
charcoal

using
cyanide-containing
coagulation,
compounds,
by
water
.
adsorption.
14.1).
159
14.3
Ozone
in
Learning outcomes
the
Ozone
The
On
completion
of
this
atmosphere
section,
in the
stratosphere
atmosphere
is
the
part
of
the
atmosphere
about
20–50 km
above
the
you
Earth.
Ozone,
,
O
is
present
in
the
stratosphere
in
a
‘layer ’
which
varies
in
3
should
be
able
to:
thickness.

explain
ozone
how
in
the
the
concentration
atmosphere
of
per
The
million,
ozone
absorbs
which
is
harmful
present
at
ultraviolet
a
concentration
(UV)
radiation
of
about
from
the
10
parts
Sun.
is
maintained
The

understand
the
importance of the ozone
The
‘photodissociation’
ozone
light

describe
the
signicance
describe
of CFCs
some free
reactions
in
human
health
layer
reaches
is
important
surface
of
for
human
health
because
if
too
much
UV
Earth:
environmental
in
the
ozone
layer

layer to
term
the
radical

there
is

the

people

we
an
skin
increased
ages
are
risk
of
sunburn
and
skin
cancer
faster
more
likely
to
get
cataracts
in
their
eyes
upper
may
have
reduced
resistance
to
some
diseases.
atmosphere

describe
the
effects
of
ozone
on
Ozone formation
human
life
(referring
stratosphere
and
to
in the
stratosphere
the
troposphere).
In
the
on
stratosphere,
oxygen.
light
(usually
enough
free
This
(see
ozone
a
to
cause
which
Section
is
formed
naturally
photodissociation
ultraviolet
energy
radicals,
ssion
is
light)
causes
oxygen
are
very
bond
molecules
reactive.
by
the
reaction
a
action
is
The
dissociate
an
of
reaction
breaking.
to
This
–
to
example
UV
in
UV
light
form
of
light
which
has
oxygen
homolytic
2.1).
UV
light
2O•(g)
(g) →
O
2
oxygen
An
oxygen
radical
can
react
with
O
(g)
an
+
oxygen
O•(g)
→
molecule
O
2
Ozone
is
oxygen
also
free
broken
radical
down
are
by
UV
Dutch
scientist
Martin
the
absence
was
the rst
person
to
distinctive
machinery
later found
smell
was
to
when
due
to
of
ozone
is
ozone
‘ozein’
comes from
which
means
to
the
Sun.
Oxygen
an
factors
(g)
+
O•(g)
2
in
balance
decomposing
with
the
rate
of
the
ozone,
the
breakdown.
rate
So
of
the
of
ozone
in
the
atmosphere
remains
constant.
was
ozone. The
chemicals
the Greek
smell.
Chlorofluorocarbons
toxic
and
are
atmosphere
reach
the
A
cycle
Section
(CFCs)
unreactive
for
Highly
involving
2.1).
We
of
reactive
use
the
free
as
refrigerants
normal
years.
where
initiation,
shall
used
under
hundreds
stratosphere,
molecules.
After
UV
many
light
radicals
CFC
by
Initiation:
not
the
The
C—F
F
UV
light
is
strong
enough
to
break
the
UV
CCl
F
2
2
light
→
Cl•
+
•CClF
2
not
the
may
these
homolytic
CCl
bond.
in
molecules
ter mination
chlorouorocarbon,
are
persist
decompose
formed
and
aerosols
They
years,
can
are
propagation
the
and
conditions.
2
160
and
light
(g) → O
other
Ozone-depleting
word
from
electrical
working. This
be
any
(g)
record
amount
a
of
ozone.
van
formation
Marum
light
3
In
1785
form
3
UV
In
to
formed.
O
Did you know?
radical
ssion.
occurs
as
an
(see
example.
2
C—Cl
bond
but
Chapter
Propagation:
Cl
free
radicals
can
Cl•
+
then
O
→
attack
ClO•
ozone
+
+
result
of
these
reactions
is
O
→
Cl•
ozone
(g)
→
+
In
Cl•
these
100 000
radicals
to
radical
chain
ozone
high
jet
present
Earth’s
Other
in
surface)
may
low
the
can
because
chlorine
before
a
of
it
radical
2O
converted
is
to
constantly
may
termination
CFCs
and
in
the
break
oxygen.
reaction
compounds
to
ozone
being
down
reformed.
about
between
atmosphere
trichloroethane.
contribute
two
therefore
may
also
Nitrogen
free
leads
have
oxides
this
from
depletion.
level ozone
troposphere
be
e.g.
(g)
chloro - organic
also
environment
2
catalyst
a
presence
aircraft
effects of
Ozone
a
tetrachloromethane
ying
The
The
depletion .
e.g.
as
molecules
occurs.
ozone
effect,
acts
reactions,
is
3O
3
The
the
2
that
2O
and
2
3
The
Chemistry
O
3
ClO•
molecules,
14
toxic
to
(the
plant
layer
and
of
the
animal
atmosphere
life.
It
next
to
can:
Exam tips

irritate
the
respiratory
been
linked
have
a
to
system
increased
and
cause
incidences
of
breathing
asthma
and
difculties.
It
has
bronchitis.
The

bad
affect
cholesterol-like
cardiovascular
on
the
heart
compounds
problems
and
to
such
blood
form
as
in
vessels.
the
It
lungs.
atherosclerosis
may
These
cause
may
(hardening
effect
depletion
cause
of
the
the
of CFCs
of
the
production
troposphere
as
on
the
ozone
of
a
layer
ozone
result
in
of
and
the
the
arteries).
interaction
Ozone
is
dioxide
one
from
reactions
and
in
of
the
car
the
nitrogen
factors
exhausts
presence
dioxide
is
contributing
(see
of
Section
UV
light.
to
photochemical
14.8)
can
Ozone
is
undergo
formed
smog.
Nitrogen
examples
photolytic
during
this
cycle
sure
that
related
UV
NO
+
nitric
dioxide
oxide
+
→
O
chain
you
to
light
nitrogen
are
reactions.
know
and
these
with
exhausts
the
both
Make
initiation,
termination
steps
reactions. We rst
O•
came
nitrogen
O•
car
light
→
2
of
propagation
regenerated.
NO
of UV
oxides from
oxygen
across
these
in
Section
2.
1.
free
radical
O
2
3
ozone
NO
+
O
→
NO
3
When
hydrocarbons
disrupted
organic
and
ozone
radicals.
photochemical
and/or
reacts
These
smog
are
(see
+
O
2
carbon
with
2
monoxide
unsaturated
responsible
Section
for
are
present,
this
hydrocarbons
many
of
the
to
cycle
gets
produce
harmful
effects
of
14.8).
Key points

The
concentration
involving free
radical

Photodissociation

CFCs
can
radicals
deplete
and
Stratospheric

Tropospheric
nitrogen
is
the
ozone
ozone
oxides
ozone
in
the
atmosphere
is
maintained
by
a
cycle
reactions.
the
initiated

of
of
breaking
ozone
by
layer
and
be
a
by
ultraviolet
protects
can
of
bond
catalytic
light,
usually UV
reactions
light.
involving free
light.
humans from
produced
subsequent
by
by
the
the
reaction
harmful UV
photochemical
of
an
rays
of
the
Sun.
decomposition
oxygen free
radical
with
oxygen.

Ozone
is
harmful
to
plant
and
animal
life.
161
14.4
The
carbon
Learning outcomes
cycle
Carbon
The
On
completion
of
this
section,
oceans,
be
able
explain
the
importance
maintaining
carbon

explain
of
the
dioxide
the
sources
atmosphere
carbon
and
rocks
reservoirs
or
all
contain
carbon
sinks .
carbon.
The
We
call
amount
of
these
carbon
to:
in

the
you
carbon
should
sinks
balance
in
the
carbon
equilibrium
of
of
cycle
in
is
terms
of
these
because
carbon
atmosphere
concepts
each
This
from
mainly
as
reservoirs
there
these
carbon
is
a
has
not
balance
reservoirs.
dioxide,
is
changed
between
The
the
much
the
reservoir
one
which
of
over
uptake
carbon
can
millions
and
in
the
undergo
of
release
years.
of
atmosphere,
most
rapid
changes.
and
reforestation.
Releasing
There
are
several
Respiration:
complex
dioxide
oxygen
carbon
This
series
is
ways
is
of
the
into
H
6
CO
when
of
the
process
the
O
12
to
which
produce
(aq)
to
+
do
6O
into
food
such
This
CO
is
energy.
the
atmosphere.
oxidised
During
Aerobic
in
this
the
body
process
respiration
by
a
carbon
removes
this.
(g)
→
6CO
2
2
(g)
+
6H
2
as
coal,
wood
escapes
into
O(l)
2
and
the
hydrocarbons
atmosphere.
produce
When
this
2
happens,
be
in
gets
atmosphere.
Fuels
burn.
atmosphere
carbon
6
fuels:
they
which
atmosphere
C
Combustion
by
reactions
released
from
into the
due
oxygen
to
is
human
also
removed
activity
(e.g.
from
for
the
atmosphere.
transport)
or
natural
Combustion
activity
(e.g.
can
forest
res).
Other
decompositions:
atmosphere
From
by
oceans:
the
Small
amounts
breakdown
When
of
dissolves
CO
of
carbon
vegetation
in
in
are
released
into
the
swamps.
seawater
various
equilibria
are
set
2
up
involving
hydrogencarbonate
and
carbonate
ions,
e.g.
2–
(aq)
2HCO
Y
CO
3
(g)
+
H
2
O(l)
+
gases
water
in
are
the
less
soluble
oceans
gets
in
(aq)
3
hydrogencarbonate
Most
CO
2
carbonate
water
warmer
as
the
temperature
bubbles
CO
out
of
increases.
solution
and
When
the
2
equilibrium
The
above
is
uptake of
There
are
two
atmosphere:
to
the
right.
carbon from the
main
ways
in
which
photosynthesis
Photosynthesis:
during
shifted
Plants
photosynthesis
remove
to
(g)
6CO
and
+
6H
2
carbon
by
the
carbon
make
atmosphere
dioxide
is
removed
from
the
oceans.
dioxide
from
the
atmosphere
carbohydrates.
O(l)
→
C
2
H
6
O
12
(aq) +
6O
6
(g)
2
glucose
The
energy
pigment
By
in
oceans:
for
this
plants
is
CO
reaction
traps
quite
the
comes
from
sunlight
soluble
in
and
water
sunlight.
acts
and
as
a
large
Chlorophyll,
amounts
2
from
the
atmosphere
when
it
dissolves
in
oceans:
+
CO
(g)
2
162
+
H
O(l)
2
Y
HCO
(aq)
3
+
the
green
catalyst.
H
(aq)
are
removed
Chapter
Balancing
uptake
and
14
Chemistry
and
the
environment
release of CO
2
Exam tips
The
complete
carbon
cycle
is
shown
in
Figure
14.4.1.
The
carbon
two
most
features
in
important
regulating
dioxide
atmosphere
of
the
carbon
cycle
are
100
respiration
and
photosynthesis.
100
3.5
that
increases
the
other
125
120
of
drastically
extent
these
to
takes
reduces
which
place
will
or
one
or
upset
decay
the
1
carbon
cycle.
respiration
burning
(as
Anything
fossil
methane)
fuels
photosynthesis
warmer
water
dead
marshes
oceans
organisms
numbers
show
the
organisms
carbonate
of
carbon
year
transferred
in thousands
millions
of
Did you know?
amount
2–
rocks
sediments
every
HCO
of
tonnes
in
sea. After
the
to
two
processes
which
keep
Respiration
this
cycle
releases
in
CO
balance
into
the
are
air
respiration
and
takes
and
up
Photosynthesis
takes
up
from
CO
the
air
and
puts
oxygen
air
.
These
two
processes
are
carbonate
cycle
approximately
balanced
so
that
sea
animals
can
be
they
(plankton)
die,
bed. Over
plankton
content
of
the
air
remains
fairly
constant.
In
addition,
the
is
dead
millions
of
rocks,
taken
organisms form
e.g.
out
limestone. This
of
the
carbon
unless
the
carbonate
rocks
are
the
heated
CO
tiny
back
2
the
the
these
carbon
2
into
by
The carbon cycle
photosynthesis.
oxygen.
ions
3
up
years
The
and CO
taken
fall
Figure 14.4.1
ions
3
to
make
lime.
large
2
amount
of
taken
CO
up
by
the
oceans
is
balanced
by
that
released
from
2
the
oceans.
Upsetting the
The
burning
dioxide
into
of
fossils
the
If
burnt
would
we
there
are
fuels
only
atmosphere
respiration.
So
balance
fossil
putting
fuels
not
were
be
more
a
releases
compared
being
into
small
the
formed
problem.
CO
a
with
But
the
as
fossil
amount
amount
fast
as
fuels
of
they
are
carbon
released
were
not
by
being
being
formed.
atmosphere.
2
Many
people
are
worried
that
an
increase
in
the
amount
of
CO
in
the
2
atmosphere
warming
will
(see
put
the
Section
carbon
cycle
out
of
balance
and
increase
global
Key points
14.5).

As
the
world’s
population
increases,
many
forests
are
being
The
carbon
level
because
of
an
increased
need
of
land
for
agriculture,
cycle
quarrying
or
of
carbon
deforestation
means
that
less
is
CO
being
removed
from
dioxide
the
in
the
housing.
atmosphere
This
keeps
cleared
relatively
constant.
the
2
atmosphere
and
to
by
photosynthesis.
respiration
replace
those
is
altered.
lost)
is
That
So
is
important
the
why
in
balance
between
reforestation
maintaining
photosynthesis
(replanting
this
of

The
carbon
into
trees
the
balanced
dioxide

released
atmosphere
respiration
balance.
dioxide
in
by
in
living
the
uptake
the
of
is
carbon
photosynthesis.
Burning fossil fuels
deforestation
the
by
organisms
carbon
may
cycle
and
cause
to
become
unbalanced.

Reforestation
the
carbon
helps
to
rebalance
cycle.
163
14.5
Global
warming
Learning outcomes
The
The
On
completion
of
this
section,
be
able
explain
effect’
the
and
terms
‘greenhouse
‘global
if
it
describe
absorbed
effect
by
the
is
a
the
energy from
the
temperature
were
heated
of
the
directly
the
by
which
and
Earth’s
by
re-radiation
of
the
region
infrared
simplied
diagram
of
thermal
re-radiated
surface
radiation
the
some
into
process
atmosphere
in
radiation
all
from
directions
the
so
and
from
the
atmosphere
is
higher
than
Sun.
warming’
A

is
to:
that

greenhouse
effect
you
Sun
should
greenhouse
greenhouse
effect
is
shown
shorter
energy
in
wave
Figure
rays
14.5.1.
–
atmosphere.
escapes
visible
into
the
space
energy
the
radiated
Earth
infrared
as
+
UV
Sun
from
long
wave
rays
carbon
energy
dioxide
+
water
absorbed
in
by
from
the
atmosphere
greenhouse
gases
warms
the
atmosphere
energy
near
Figure 14.5.1
In
the
water
it
not

is
Earth’s
surface
Simplied diagram of the greenhouse effect
greenhouse
and
absorbed
the
vapour
exposed
Ultraviolet
effect,
to
and
wavelengths.
gases
prevent
the
the
Sun’s
visible
The
in
the
Earth
rays.
It
radiation
visible
atmosphere
from
cooling
works
from
radiation
like
the
and
such
down
as
carbon
too
dioxide
rapidly
when
this:
Sun
some
have
of
the
relatively
UV
short
radiation
pass
Did you know?
through
The
term
named
‘greenhouse
because
a
similar
in
a
greenhouse,
radiation
way
it
in
effect’
appears
to
the
letting
through
but
to
glass
was
so

air

short-wave
trapping
by
warming
up
the
air
When
idea
relating
the
surface
the
gains
Earth’s
without
radiation
being
hits
absorbed
the
Earth’s
by
carbon
surface
so
dioxide.
that
the
energy.
surface
absorbs
the
short
wavelength
rays
it
heats
the
Energy
is
lost
from
the
surface
as
radiation
with
a
longer
wavelength.
inside.
The
The rst
atmosphere
wavelength
up.

heat
the
short
Earth’s
work
and
The
radiation
emitted
is
in
the
infrared
region.
insulating

Infrared
radiation
can
be
absorbed
by
greenhouses
gases
such
as
CO
2
properties
of
the
atmosphere
were
and
put forward
by Joseph
Fourier
but
these
ideas
were
experimentally
until
Some
of
the
greenhouse
of fossil fuels
effect
was
to
in
space
The
heat
than
were
is
re-radiated
and
some
would
not
absorbed
the
atmosphere.
back
escapes
to
into
Earth
and
space.
the
Less
lower
layers
radiation
of
escapes
be
the
case
if
greenhouse
gases
such
as
carbon
present.
radiation
raises
the
temperature
of
the
atmosphere.
Svante
natural
1896.
warming.
164
in
the
This
Arrhenius
present
to

burning
naturally
1859
person
dioxide
relate
the
atmosphere
into
by John Tyndall. The rst
are
not
the
proved
which
in

1824
water
,
raising
of
the
atmospheric
temperature
is
called
global
Chapter
Global
14
Chemistry
and
the
environment
warming
Exam tips
Global
that
the
war ming
arises
Earth
reected
from
be
The
atmosphere,
the
to
the
increase
the
in
more
global
the
up
carbon
heat
is
effect.
If
than
and
absorbed
of
the
There
we
because
rather
dioxide
because
more.
temperature
cold,
surface
more
heats
in
extremely
atmosphere
atmosphere
rise
greenhouse
from
atmosphere.
and
the
the
would
away
is
is
of
did
the
the
not
have
water
re-radiated
greenhouse
enhanced
by
back
So
is
to
and
in
the
the
must
Earth
by
A
greenhouse
absorbs

main
Water
and
spectrum.
naturally- occurring
The
distinguish
greenhouse effect
the
then
the
way
Earth’s
close
re-emitted
radiation. Global
refers
to
the
radiation
surface
to
range
greenhouse
the
as
Earth’s
longer
warming
temperature
the
is
and
increase
greenhouse
effect.
gases
gas
electromagnetic
to
atmosphere
arising from
Greenhouse
to
terms
relates
surface,
warming).
able
the
absorbed
the
(an
be
global warming. The
effect
the
warming
You
between
be
the
there
effect.
global
warming,
would
absorbed
vapour
atmosphere
global
radiation
being
and
Earth’s
gases
This
radiation
absorption
greenhouse
greenhouse
vapour:
emits
The
gas,
is
naturally
may
shown
in
present
contribute
in
the
infrared
spectrum
from
of
Figure
in
the
about
part
carbon
of
the
dioxide,
a
14.5.2.
atmosphere
30–60%
of
are:
the
vis
greenhouse
present
in

Carbon
the
by
especially
atmosphere
the
water
dioxide:
in
the
lower
small
layers
amounts,
of
the
which
atmosphere.
are
kept
It
is
relatively
cycle.
is
CO
in
ecnabrosba
constant
effect
naturally
present
in
the
atmosphere.
Although
2
it
is
only
present
contributing

Methane:
to
in
at
This
is
low
least
concentrations,
30%
found
in
of
the
the
it
is
a
potent
greenhouse
atmosphere
at
greenhouse
gas
effect.
much
lower
2
3
10
concentrations
than
,
CO
but
it
absorbs
relatively
more
IR
and
may
contribute
Methane
is
formed
as
by
4
10
10
radiation
2
wavelength
much
the
as
5–10%
action
of
of
the
bacteria
greenhouse
in
the
(nm)
effect.
digestive
system
of
Fig. 14.5.2
The absorption spectrum of
carbon dioxide
animals
paddy
Ozone,
and
by
the
bacterial
decay
in
marshes
as
well
as
from
rice
elds.
CFCs
and
nitrogen
oxides
are
also
effective
greenhouse
gases.
Key points
Enhanced
global
warming
and
climate
change

Over
the
past
150
years
the
amount
of
CO
in
the
atmosphere
has
The
greenhouse
effect
is
a
been
2
process
increasing
stations
because
and
for
of
the
increased
transport.
The
burning
present
of
fossil
percentage
fuels
of
in
in
CO
by
which
thermal
power
radiation
the
is
absorbed
by
the
2
atmosphere
The
is
nitrogen
oxides
atmosphere
in
concentration
warmer

melting


of
0.039%,
of
other
years
for
greenhouse
can
ice
rainfall
50
ozone,
the
gases
affect
caps
low-lying
the
whereas
greenhouse
tropospheric
recent
of
polar
reducing
of
and
atmosphere
ooding

about
concentrations
and
our
same
leads
years
gases,
have
been
reasons.
to
climate
hence
ago
it
such
was
as
about
increasing
The
increased
atmosphere
0.031%.
methane
so
and
in
Earth’s
the
is
increased
global
warming.
A
areas
so
sea
levels
leading
to
increased

increasing
the
rate
of
increasing
species
Global
the
the
weather
the
such
more
violent
temperature
as
corals.
An
of
the
and
unpredictable
oceans
increased
than
by
re-radiated
and
if
it
of
the
atmosphere
were
heated
radiation from
leading
amount
of
to

the
death
will
CO
be
of
also
some
be
warming
A
is
temperature
atmosphere
formation
deserts
making
surface
higher
the
some
and
temperature
the
Sun.
areas
in
the
directly
by:
raising
that
which
greenhouse
greenhouse
emits
part
the
rise
the
in
Earth’s
arises from
effect.
gas
radiation
of
the
of
in
absorbs
the
and
infrared
electromagnetic
2
released
from
the
oceans
leading
to
an
even
further
increase
in
global
spectrum.
warming.
165
14.6
The
nitrogen
Learning outcomes
On
completion
should
be
able
of
this
The
section,
cycle
nitrogen
Nitrogen
gas
chemical
reactivity.
describe

explain
forms
78%
of
the
atmosphere
by
volume,
but
it
has
low
you
Nitrogen
can
be
recycled
at
a
sufcient
rate
in
the
to:
atmosphere

cycle
the
how
nitrogen
the
cycle
diagram
of
to
allow
the
plants
nitrogen
to
grow.
Figure
14.6.1
shows
a
simplied
cycle
atmospheric
N
in
air
2
concentrations
of
the
oxides
of
N
+
O/NO/NO
2
NH
2
/NH
3
nitrogen
may
be
4
altered.
in
air
in
air
fertilisers
agriculture
vehicles
industry
sea
creatures
dissolved
N
run-off from
and
fertilisers
compounds
sediments
Figure 14.6.1
Much
of
the
catalysed
are
Simplied diagram of the nitrogen cycle
shown
catalysed
nitrogen
cycle
conversions
in
by
Figure
in
is
dominated
microbes,
14.6.2.
Many
by
plants
of
the
reactions
and
involving
animals.
reverse
These
reactions
can
enzyme-
reactions
be
microorganisms.
de
d
en
tr
mmoni
cay/a
fic
tion
fica
at
io
n
amino
proteins
N
NH
2
NO
3
nitrogen
nitrogen
NO
2
ammonia
acids
in
amino
+
animals
acids/
3
nitrites
nitrification
nitrates
nitrification
proteins
in
plants
assimilation
fixation
Figure 14.6.2
Exam tips
Reactions

The
nitrogen
You
need
cycle
is
very
Some biological oxidations and reductions involving nitrogen compounds
which
Denitrication:
reactions
biological
learn
below
the
rather
conversions
nitrogen
Denitrifying
into the
bacteria
occur
atmosphere
under
both
aerobic
and
complex.
anaerobic
only
release
conditions
in
the
soil
and
in
the
oceans.
They
use
organic
basic
than
of
all
compounds
to
reduce
compounds
are
nitrates
to
nitrogen
gas.
The
organic
the
oxidised
to
carbon
dioxide.
ammonia
+
O(aq)
5CH
to
+
4NO
2
proteins.
(aq)
+
4H
(aq)
→
2N
3
(where
CH
O
is
a
(g)
+
5CO
2
simplied
formula
for
a
(g)
+
7H
2
O(l)
2
sugar)
2
The
nitrates
remains

or
Ammonium
oxidation
largely
animal
in
The
of
166
sea.
The
and
which
for
fertilisers
fertilisers,
decomposition
nitrogen
gas
fertiliser
This
nitric
run
oxides
can
ammonium
ammonium
ammonia
and
of
Nitrogen
and
remove
Process :
atmosphere
make
oxidation:
the
Haber
from
conversion
ammonia
remains
Reactions

arise
from
ions
be
ions
animal
by
arise
by
bacteria.
from
and
plant
nitrates.
reformed
anaerobic
This
decaying
occurs
plant
off.
nitrogen from the
removes
nitrogen
synthesis.
acid.
of
into
The
atmosphere
directly
nitrogen
is
from
then
the
used
to
and
Chapter

Lightning:
nitrogen
further
which

The
to
reactions
dissolve
Nitrogen
be
aerobic
by
nitrifying
nitrates
Car
or
to
in
Nitrogen
the
the
bacteria
The
are
called
or
into
in
soil.
emitted
to
oxygen
which
and
the
environment
and
can
removed
then
combine.
from
show
the
that
then
be
undergo
as
nitrates
exhaust
of
gases.
convert
bacteria
to
nitrates
a
car
This
of
engine
can
oxides
mixture
gases
are
Some
found
14.6.2).
nitrogen
different
Did you know?
can
dissolved
Figure
inside
mixture
several
the
(see
pressure
A
can
converted
absorb
proteins
and
algae
nitrogen-xing
can
and
temperature
NO
nally
blue-green
The
Plants
acids
to
cause
formed,
being
ammonia
amino
oxygen
are
or
ammonia.
the
lightning
Chemistry
groundwater
.
bacteria
The
in
high
and
which
sometimes
sea
Certain
synthesise
of
oxides
atmosphere,
anaerobic.
nitrogen
formed,
temperatures
nitrogen
engines:
cause
in
xation:
atmospheric

high
combine.
14
is
is
in
swellings
beans
and
swellings
Farmers
beans
formed:
nitrogen-xing
are
on
because
the
are
plant
roots
clover
plants. These
called
root
sometime
or
bacteria
clover
they
nodules.
plough
back
into
increase
crops
the
the
of
soil
nitrogen
x
content
N
(g)
+
O
2
N
(g)
High
temperature
causes
The
The
nitrogen
(g)
+
2O
balance of the
atmosphere
remains
main
more
parts
of
has
or
the
nitrogen
atmosphere
amount
from
exhausts
and
affect
amounts
by
the
removed
removed
not
for
the
of
industry
very
air
due
working
nitrogen
Oxides
of
Nitrous
nitrogen
oxide,
N
to
is
to
form
days
balanced
The
in
these
nitrogen
these
put
by
is
of
its
furnaces
oxides.
the
natural
of
the
is
atmosphere
14.7
as
that
the
the
also
from
present
of
from
same
oxides
the
Sections
processes
nitrogen
presence
the
by
nitrogen
about
at
process,
nitrogen
More
the
concentration
Haber
nitrogen
the
(see
of
now
processes
cycle,
into
so
the
removal
xation.
formation
problems
of
xation
fertilisers
being
being
vehicle
time
may
increasing
by
and
vehicles
and
14.8).
atmosphere
recycled
added
temperature
nitrogen,
the
the
nitrogen
in the
are
of
nitrogen
the
the
oxides
O
were
of
(g)
cycle
roughly
particular
Nitrogen oxides
high
sink
Although
of
2NO
combine
atmosphere.
bacterial
industry
.
poses
was
the
→
2
Before
cycle
production
by
the
large
constant.
into
to
nitrogen
which
back
(g)
The
oxygen
nitrogen
microorganisms,
put
a
less
soil.
2NO(g)
2
furnaces:
and
the
2
2

→
of
in
to
the
the
atmosphere
atmosphere
by
by
natural
processes.
denitrication
2
reactions.
Nitric
oxide,
NO,
and
nitrogen
dioxide,
NO
,
are
produced
2
during
thunderstorms:
Key points
(g)
N
+
O
2
(g)
→
2NO(g)
and
N
2
(g)
+
2O
2
(g)
→
2NO
2
(g)
2

Nitrous
oxide
passes
from
the
lower
atmosphere
to
the
stratosphere,
Processes
from
it
is
converted
to
and
N
NO
by
photolytic
reactions
initiated
by
UV
that
remove
nitrogen
where
the
atmosphere
include
light:
2
the
N
O(g)
→
NO(g)
+
Haber
process,
lightning
and
N•(g)
2
nitrogen xation.
O(g)
N
→
N
2
(g)
+
O•(g)
2

Nitric
oxide
can
form
by
the
reaction
of
N
O
with
the
oxygen
free
radicals
to
2
formed
by
the
latter
reaction
or
from
the
decomposition
of
Processes
ozone:
the
that
add
nitrogen
atmosphere
denitrication
include
and
ammonia
oxidation.
O(g)
N
+
O•(g)
→
2NO(g)
2

The
NO
formed
can
catalyse
the
decomposition
of
ozone.
Some
NO
The
concentration
oxides
also
react
with
either
oxygen
free
radicals
or
ozone
to
form
acidic
of
nitrogen
can
in
the
atmosphere
is
NO
2
increasing
which
can
contribute
to
acid
rain
(see
Section
part
of
the
nitrogen
cycle
is
of
concern
to
many
scientists
are
affecting
it
to
a
considerable
nitrogen
produced
extent
(see
Sections
by
vehicle
because
emissions
humans
of
14.7).
oxides
This
because
14.7
and
high
temperature
and
furnaces.
14.8).
167
14.7
Acid
rain
Learning outcomes
What
Rain
On
completion
of
this
section,
be
able
the
describe
the
products
of
containing

explain
naturally
rain?
air
.
This
slightly
rain
effects
of
the
combustion
of fuels
If
acid
the
rain.
acidity
This
atmosphere
is
of
pH
due
of
to
carbon
about
5.6.
dioxide
But
this
reacting
is
not
with
classed
water
as
rain
caused
by
with
falls
below
oxides
water
of
about
sulphur
pH
5,
and
the
rain
nitrogen
is
acid
in
called
the
vapour
.
sulphur
how
oxides
nitrogen.
acidic
a
the
reacting
acid
rain
is formed
Acidic oxides
from
has
to:
rain.

acid
you
in
should
is
is
of
sulphur
in the
air
and
Coal
also
and
before
to
natural
contain
the
fuel
sulphur
gas
small
is
contain
amounts
sold.
dioxide,
When
which
some
of
is
these
an
S(s)
sulphur
sulphur
,
fuels
acidic
+
are
→
third
of
are
the
Nitrogen
natural
oxides
temperature
nitrogen
a
sulphur
can
also
furnaces.
dioxide
is
source
dioxide
an
formation
Figure
14.7.1
of
acidic
acid
shows
get
rain
it
for
is
transport
removed
sulphur
is
oxidised
(g)
dioxide.
pollutes
the
oxide
air
the
from
and
They
produce
nearly
a
atmosphere.
car
nitric
exhausts
oxide
are
and
not
from
acidic
high
but
gas.
acid
these
the
Fuels
of
2
sulphur
into
Nitrous
The formation of
The
of
which
burnt,
SO
2
V
olcanoes
most
gas:
(g)
O
impurities.
although
rain
involves
two
stages:
oxidation
and
deposition.
stages.
2–
SO
4
+
oxidation
H
H
O
SO
2
4
2
SO
3
dry
SO
reaction
burning
vehicle
acidified
exhausts
surfaces
reactions
by
atmosphere.
trioxide
and
of
2
fossil fuels
dioxide
Oxidation
in
the
nitrogen
Sulphur
nitric
nitric
in the
atmosphere
atmosphere
dioxide:
dioxide
oxide.
oxide
SO
The
with
(g)
+
is
This
reacts
oxidised
can
with
nitrogen
oxygen
NO
2
(g)
in
→
take
then:
2NO(g)
O
(g)
2
a
place
dioxide
the
is
variety
fairly
catalysts.
quickly
dioxide
then
of
to
in
form
reformed
the
sulphur
by
air
.
SO
2
+
by
nitrogen
(g)
+
NO(g)
3
sulphur
168
deposition
The formation of acid rain
Oxidation
Sulphur
wet
NO
2
Figure 14.7.1
deposition
→
trioxide
2NO
(g)
2
nitric
oxide
Chapter
The
NO
which
is
reformed
can
go
on
to
oxidise
another
SO
Chemistry
and
the
environment
molecule.
2
This
14
2
process
can
be
repeated
to
oxidise
many
more
molecules.
SO
The
2
acts
NO
as
a
catalyst.
2
Oxidation
in
the
involving
atmosphere
free
and
radials:
so
do
These
not
reactions
occur
until
often
the
SO
take
has
place
moved
higher
up
to
2
these

levels.
Examples
Oxidation
with
are:
oxygen
SO
free
(g)
+
radicals
O
2

Oxidation
to
formed
the
O
(H
by
+
O•
→
→
ozone:
SO
3
sulphates
action
(g)
or
by
of
OH•
O•
(g)
+
O
3
radicals.
radicals
(g)
2
The
from
OH•
ozone
radicals
with
are
water
2OH•).
2
several
OH•(g)
+
SO
(g)
→
HSO
2
Nitric
oxide
radicals
or
from
ozone
car
to
exhausts
form
the
can
H
react
gas,
with
nitrogen
SO
2
→
also
acidic
steps
•(g)
3
either
4
oxygen,
dioxide,
free
NO
2
NO(g)
+
O•(g)
→
NO
(g)
or
NO(g)
+
O
2
Acid formation
Wet
deposition:
atmosphere
form
acid
a
dilute
with
solution
trioxide
or
of
and
dissolve
NO
(g)
+
O
2
(g)
2
small
water
acid.
particles
vapour
This
of
in
falls
sulphates
the
with
in
the
atmosphere
the
rain
to
to
form
rain.
(g)
+
H
3
Nitrogen
dioxide
atmosphere
to
in
the
from
a
2NO
Some
sulphur
sulphurous
(g)
+
H
of
O(l)
These
nitric
may
when
Small
or
it
→
such
as
and
with
water
vapour
react
in
the
(aq)
+
HNO
(aq)
2
directly
with
water
to
form
raining.
(g)
+
H
O(l)
→
H
2
particles
dry
plants
(aq)
4
acid.
HNO
of
acid
sulphates
reacts
and
SO
and
SO
2
(aq)
3
and
with
SO
2
surfaces
SO
3
also
is
sulphuric
compounds
reacts
nitric
2
deposition:
H
2
SO
when
→
2
atmosphere
solution
dioxide
acid
O(l)
2
2
air
in
sulphuric
SO
Dry
→
(deposition)
Sulphur
react
(g)
3
nitrates
ammonia
gases
can
be
can
in
form
the
in
the
atmosphere.
deposited
on
moist
3
wet
buildings
to
form
acids.
Key points
The
effects of
acid
rain


T
rees
may
forest
have
their
leaves
and
roots
damaged.
This
can
lead
to
When fuels
are
burnt,
containing
sulphur
sulphur
dioxide
is
death.
formed.

Lakes

Soil
and
rivers
become
acidic.
Some
aquatic
organisms
may
die.

may
leached
become
out
of
too
the
acidic
to
grow
crop
plants
and
minerals
may
be
Sulphur
dioxide
atmosphere
Buildings

Metals
made
from
structures
carbonate
such
as
rocks
bridges
may
and
be
eroded.
railings
may
200 km
may
fall
trioxide
from
far
and
their
from
the
nitrogen
sources.
source
oxides
So
the
of
pollution.
can
effects
be
carried
on
the
Sulphur
by
be
obvious
radicals
the
and
Sulphur
trioxide
close
to
the
to form
or
sulphur
sulphates.
vapour
reacts
to form
with
dilute
dioxide,
winds
as
environment
far
will
sulphuric
as
acid
in
the
rain.
not

always
dioxide
trioxide
water
rain
sulphur
by free
in
corrode.

Acid
oxidised
soil.
nitrogen

is
Nitrogen
oxides
can
be
oxidised
sources.
to form
nitrogen
dissolves
nitric
in
dioxide,
water
vapour
which
to form
acid.
169
14.8
Pollution from fuels
Learning outcomes
Primary
and
Atmospheric
On
completion
of
this
section,
be
able
(particulates)
describe
the
difference
and
secondary
describe
the
effect
of
pollutants:
monoxide
fossil
of
combustion
as
environment
describe
the
and
on
of
liquid
or
tiny
particles
of
and
on
are
released
directly
from
a
process,
e.g.
from
fuels,
car
exhausts,
particulates
sulphur
released
dioxide
from
released
erupting
from
volcanoes
a
waste
product
of
animal
digestion.
Other
or
primary
resulting
from
human
activity
include:
the

nitric

carbon
of
oxide

lead
and
volatile
the
dioxide
nitrogen
from
dioxide
lime
kilns
from
and
car
from
exhausts
combustion
of
fossil
in
car
fuels
lead
organic
and
compounds
These
humans
effects
compounds
and
droplets
air
.
of
pollutants
hydrocarbon fuels

the
the
methane
products
gases,
pollutants
burning

be
with
between
carbon
primary
can
mixed
to:
Primary

pollutants
pollutants
you
solids
should
secondary
and
lead
small
compounds
particles
of
from
combustion
reactions
engines
paints
environment

humans
volatile
organic
compounds
e.g.
unburnt
hydrocarbons
from
vehicle
engines

explain
the
term
‘photochemical

smog’.
CFCs
from
Secondary
primary
arising
refrigerants
pollutants:
pollutants
from

sulphur

ozone
human
nitrogen

organic

particles
the
These
undergo
trioxide
in
from
and
salts
now
formed
in
the
reactions.
atmospheric
from
oxygen
formed
formed
banned).
atmosphere
Secondary
when
pollutants
include:
troposphere
dioxide
are
further
activity
compounds
of
(although
in
(see
in
oxidation
the
Section
smog
the
of
sulphur
photochemical
(see
14.3
dioxide
cycle
and
involving
below)
below)
atmosphere,
e.g.
nitrates
from
NH
3
and
acids
Burning
in
air
.
hydrocarbon fuels
Incomplete
When
the
combustion
hydrocarbon
formed,
which
present,
is
a
fuels
hydrocarbon
monoxide,
CO,
is
undergo
greenhouse
fuels
formed
H
2C
4
(see
undergo
as
(g)
complete
gas
+
well
9O
10
combustion
Section
14.4).
incomplete
as
(g)
soot
→
carbon
not
particles
+
10H
2
of
dioxide
enough
combustion.
(small
8CO(g)
If
air
is
is
Carbon
carbon).
O(l)
2
Exam tips
2C
H
4
Some
well
pollutants
as
can
secondary
example,
NO
is
be
primary
pollutants.
a
primary
as
Particles
haem,
For
pollutant
of
the
present
in
soot
are
oxygen
red
(g)
+
5O
10
irritants.
carrying
blood
(g)
→
8C(s)
+
10H
2
cells.
Carbon
group
It
O(l)
2
in
monoxide
the
prevents
protein
oxygen
is
toxic.
It
combines
haemeoglobin
from
binding
to
which
haem
with
is
and
2
when
emitted from
but
a
is
secondary
car
exhausts,
pollutant
can
lead
to
when
Unburnt
formed
in
the
atmosphere from
ozone.
between
So
when
nitric
oxide
answering
an
hydrocarbons
not
enough
oxygen
on
primary
and
make
sure
that
context
understand
the
pollutant
being formed.
released
into
the
atmosphere
if
there
smog
in
combines
with
oxygen
in
the
high
temperature
of
car
engines
to
you
which
oxides
of
nitrogen
).
(NO
In
the
presence
of
hydrocarbons
from
car
x
the
exhausts,
smog.
170
be
them.
exam
form
is
also
burn
secondary
Nitrogen
pollutants,
to
and
Photochemical
question
may
the
is
reaction
death.
ozone
This
is
and
made
sunlight,
worse
in
this
cities
mixture
where
a
reacts
layer
to
of
form
warm
photochemical
dry
air
traps
a
Chapter
layer
dry
of
air
cooler
allows
air
beneath
the
it
(temperature
maximum
amount
of
inversion).
UV
light
to
The
be
layer
of
warm
14
Chemistry
and
a
the
environment
warm
air
transmitted.
cooler
Figure
14.8.1
shows
how
a
photochemical
smog
air
NO
forms.
CO
Nitrogen
dioxide
from
car
exhausts
can
undergo
photolytic
reactions
in
C
H
n
the
presence
dioxide
is
of
UV
light.
Ozone
is
formed
during
this
cycle
and
regenerated.
UV
b
UV
NO
O•
+
NO
O
+
O
→
NO
hydrocarbons
Ozone
and/or
reacts
+
monoxide
these
carbon
2
3
more CO
O
2
carbon
with
+ O
2
3
O
3
disrupted.
+ O•
NO
→
2
NO
radiation
light
→
2
When
2n+2
nitrogen
+ C
H
n
2n+2
2
are
present,
compounds
this
to
cycle
produce
gets
organic
c
radicals
such
as
O•
CH
and
HCO•.
These
combine
with
nitrogen
oxides
NO
3
+ O
x
to
form
cause
may
aldehydes,
irritation
also
higher
be
of
peroxides
the
present,
molar
eyes,
and
breathing
including
masses.
The
organic
some
nitrogen
nitrates.
difculties
nitrates,
dioxide,
These
and
asthma.
aldehydes
which
compounds
is
an
and
aldehyde
Particulates
ketones
higher
concentrations,
gives
the
smog
a
brownish
irritant
and
+ C
H
n
2n+2
+
nitrates
with
toxic
Figure 14.8.1
in
+ CO
3
can
colour
.
The formation of
photochemical smog; a Early morning:
temperature inversion prevents the
dispersion of NO
, CO and hydrocarbons;
x
Lead
compounds
and the
environment
reacts with O
b Slightly later: NO
2
form ozone.
Lead
and
lead
compounds
are
toxic.
They
can
affect
the
heart,
bones
and
reaction of O
3
kidneys.
Lead
particularly
permanent
paint

fuel
harmful
containing
V
olatile
ozone
nervous
is
tetraethyl
layer
.
the
system
aqueous
of
environment
children.
problems.
and
VOCs
combustion
(VOCs)
methanal
children.
get
Lead
and
Methane
It
gets
can
into
is
, NO
and hydrocarbons to
x
form smog.
cause
the
of
as

by
leakage

by
evaporation
from
cleaning

by
evaporation
from
paints
refrigerants
the
fuel
burn
more
engines.
environment
compounds
methanal,
the
can
a
make
such
with
low
membranes
affect
the
greenhouse
of
as
the
immune
gas
and
methane,
boiling
points.
eyes,
nose
system,
CFCs
deplete
the
atmosphere:

of
products
the
is
to
vehicle
are
and
irritate
effects
into
in
and the
compounds
allergic
(added
combustion
compounds
have
in
in
burnt
compounds
organic
especially
and
behavioural
lead
lead
chlorocarbon
lungs,
the
undergoes
Chlorocarbons
and
to
and
containing
Organic
atmosphere
when:
smoothly)
CFCs,
the
learning
environment

in
to
2
c Late morning and afternoon:
paints
from
and
old
glues
in
building
materials
refrigerators
products
and
used
which
contain
them
glues.
Key points

Primary
pollutants
pollutants


Combustion
of
CO
gas,
–
a
toxic
Photochemical
nitrogen

Lead
are
are formed
and
smog
and
volatile
burn
may
is formed
vehicle
a
process.
pollutants
lead
photochemical
organic
or
directly from
primary
hydrocarbons
oxides from
when fuels
released
when
to
Secondary
react further
global
warming,
in
the
the
air.
emission
of
smog.
when
ozone
reacts
with
hydrocarbons
and
exhausts.
compounds
evaporate
into
the
can
be
released
into
the
atmosphere
air.
171
14.9
Controlling
Learning outcomes
pollution
Introduction
Many
On
completion
of
this
section,
of
the
fuels
environment
should
be
able
describe
and
methods
preventing
of
controlling
atmospheric
pollution

describe
rain.
the
design
more
electric
importance
of
carbon
is
transit

in
describe
and
as
coal
and
such
as
petrol,
pollute
increased
the
global
also
preventing
the
and
fuels
are
emissions.
better
for
so
that
powered
being
For
the
by
helps
fewer
to
pollutants
batteries
do
developed
example,
make
than
are
are
warming
as
a
chemical
For
carbon
cleaner
alcohol
the
and
formed.
produce
which
making
environment
not
engine
and
production
by
and
example,
dioxide.
and
fuel
plant
reduce
fermentation
use
of
cleaner fuels,
technology
sequestering
washers
such
problems
technology
efcient
vehicles
petroleum
improved
use,
cause
Improved
Alter native
alternative
and
to:
acid

we
you
and
pollution
importance
of
agents, lters,
scrubbers
fractions
(see
Section
13.4).
mass
Hydrogen
only
cells
is
a
product.
used
to
non-polluting
Hydrogen
power
can
some
fuel.
be
When
used
vehicles
as
it
a
burns
fuel
(Figure
in
in
oxygen,
water
is
hydrogen–oxygen
the
fuel
14.9.1).
in
electron flow
porous
controlling
porous
negative
positive
pollution.
electrode
electrode
coated
coated
V
with
with
platinum
platinum
+
H
hydrogen
oxygen
water
electrolyte
(acid)
membrane
Figure 14.9.1
Carbon

A hydrogen–oxygen fuel cell
emissions
mass
transit
individual
can
also
using
be
reduced
vehicles
such
by:
as
buses
and
trains
rather
than
cars

using
simpler
forms

using
alternative
of
transport,
energy
sources,
such
e.g.
as
cycles
solar
power
,
wind
power
,
wave
power
.
Improved
technology
fuels
be
may
electric
cars
needed
and
Catalytic
Catalytic
oxides,
to
to
not
make
make
solve
the
all
the
problems.
electricity
hydrogen
for
fuel
to
converters
platinum–rhodium
nitrogen
hydrocarbons
are
and
tted
and
catalyst
gas
and
carbon
to
carbon
cars
recharge
causes
carbon
+
to
reduce
nitrogen
oxides
monoxide
may
2CO(g)
→
to
also
(g)
N
the
Once
2NO
(g)
+
4CO(g)
2
Sequestering
172
from
the
the
fossil
batteries
in
N
to
be
reduce
+
nitrogen
the
converted
dioxide.
the
2CO
of
up,
to
Unburnt
nitrogen
oxides.
(g)
2
(g)
+
4CO
2
(g)
2
agents
agents
air
.
→
emissions
warmed
carbon
2
or
example,
cells.
monoxide.
monoxide
2NO(g)
Sequestering
For
converters
hydrocarbons
harmless
does
They
are
agents
often
that
form
remove
complexes
particular
with
metal
ions
ions
from
(see
solution
Unit
1
Chapter
Study
Guide ,
Section
13.4).
They
can
be
used
to
remove
metals
ions
14
Chemistry
and
the
environment
from
2+
the
soil,
from
contaminated
water
or
from
the
air
.
For
example
and
Cu
Exam tips
2+
ions
Ni
agents
such
removed
then
as
adding
be
be
mixture
so
separated
such
that
using
water
EDT
A
waste
surfactant
pH
from
of
industrial
a
the
removed
a
from
adjusting
then
can
the
by
and
adding
chitosan.
products
as
a
by
is
mixture
Heavy
adding
long-chained
complex
methods
a
a
separate
metals
The
in
polar
removed
from
removes
these
and
water
ions
non-polar
by
as
adding
an
solvents.
sodium
insoluble
can
acid
of
You
be
agent
and
complex
molecules
2+
solubility
sequestering
sequestering
carboxylic
uncharged.
which
of
do
details
not
of
converters
can
You
different
have
to
how fuel
or
should,
importance
know
cells,
scrubbers
however,
of
these
precise
catalytic
work.
know
in
the
reducing
2+
and
Ca
Mg
ions
hexametaphosphate
can
be
pollution.
which
complex.
Scrubbers
Scr ubbers
scrubbers
high
remove
work
pressure
the
tank
the
cleaned
or
in
a
particles
rather
against
spiral.
air
sometimes,
like
the
The
escapes
from
waste
gases
spin
dryer
.
The
a
side
of
dirty
from
a
cylindrical
water
the
in
runs
top.
factory.
gases
tank.
down
This
a
waste
The
the
process
sprayed
water
side
is
Modern
are
of
the
called
at
moves
tank
wet
up
and
scrubbing
washing.
Flue-gas desulphurisation
Flue-gas
process,
desulphurisation
acids,
harmful
waste
substances
gases
moving
alkalis
in
bed
sulphite
of
in
power
solid
formed
is
or
is
an
other
waste
gases.
stations
calcium
either
and
+
of
scrubbing
reactions
Sulphur
furnaces
carbonate
dumped
(g)
SO
example
chemical
or
(s)
into
→
SO
(g)
+
can
oxide.
CaSO
(s)
+
to
be
the
removed
CaO(s)
→
CaSO
this
from
through
a
calcium
acid.
CO
3
2
In
neutralise
gases
The
sulphuric
3
washing).
used
passing
calcium
made
CaCO
2
or
dioxide
by
(air
are
(g)
2
(s)
3
Filters
Filters
are
chemical
of
long
drawn
used
to
plants
polyester
though
14.9.2).
opposite
The
remove
and
some
‘socks’,
the
lter
lters
is
direction
dust
which
and
cleaned
and
and
power
particulates
stations.
allow
the
gases
dust
the
by
dust
from
lters
through,
collects
periodically
collecting
Air
on
the
passing
as
a
the
waste
consist
but
not
outside
air
of
gases
a
in
to
chimney
number
dust.
Air
is
(Figure
through
in
the
air
solid.
sucked
through
polyester
Washing
‘sock’
dust
collecting
Materials
the
such
as
metal
contaminating
dust
ores
and
undergo
clays.
high
pressure
W
ashing
may
washing
also
to
remove
dirty
air
in
remove
soluble
dust
contaminants
from
a
substance.
removed
Figure 14.9.2
A bag lter used to collect
dust from waste gases
Key points

Pollution
ethanol,
by

can
be
reduced
improving
means
Pollution
of
mass
can
be
by
using
technology,
transport,
reduced
by
cleaner fuels
e.g.
e.g.
more
buses
using
such
efcient
and
as
hydrogen
engines
and
or
by
travelling
trains.
sequestering
agents, lters,
washers
and
scrubbers.
173
14.
10
Saving
resources
Learning outcomes
Reduce,
reuse,
Reduction of
On
completion
should
be
able
of
this
section,
to:
understand
W
aste
reuse


and
terms
reduction
describe
the
in
reduction
waste
and
plastic,
steel
describe
importance
and
to
such
steel
involved
glass,
reduce
and
Reuse

Repairing
of

of
(waste
created.
minimisation)
Examples
glass,
the
use
of
second-hand
is
the
prevention
of
waste
are:
broken
of
products.
items
instead
of
replacing
them,
e.g.
mending
a
cup.
Designing
paper,
aluminium
as

broken
recycling
how
materials
plastic,
processes
the
reusing
being
reduce,
recycle
understand

the
waste
you
material

recycle
plastic
products
shopping

Avoiding
the

Cleaning

Designing
use
of
articles
to
be
reusable
(using
cotton
shopping
bags
instead
plastic
cutlery.
bags).
disposable
before
products,
e.g.
disposable
recycling.
paper,
products
that
use
less
material
to
achieve
same
purpose,
aluminium.
e.g.lighter
same
aluminium
drinks
cans
or
lighter
steel
frames
with
the
strength.

Reducing

Improving
rather
excess
the
than
paper
or
durability
plastic
of
an
packaging.
item,
e.g.
making
a
sieve
of
aluminium
plastic.
Reuse
Reuse
means
purpose

and
to
use
something
sometimes
Rellable
drinks
for
bottles
a
more
than
different
(glass
or
once,
purpose.
plastic)
sometimes
Examples
which
can
for
the
same
are:
be
rewashed
and
reused.

Using
a
glass

Retreading

Reusing
jar
to
rubber
metal
put
owers
in.
tyres.
shipping
containers
or
wooden
chests
for
removals.
Recycling
Recycling
prevents
of
fresh
from
is
raw
sure
that
you
difference
between
reduction:
reduce,
and
can
apply
know
the
the
Rs
3
different
product
reuse
these
to
and
glass,
are
materials
of
waste
process
paper
that
have
of
to
and
plastic.
recycling
means
chemical
or
that
there
is
reduces
energy
either
use
produce
converted
into
paperboard
requires
be
into
materials,
and
fresh
products.
reduces
the
reduces
pollution
This
consumption
arising
sorted
It
also
from
transport
and
time
usually
a
new
recycled
paper).
to
and
the
supply
paper)
The
a
the
same
produce
a
slightly
disadvantages
recycling
energy
produces
of
or
are
centres,
required
product
of
for
lower
of
the
the
quality.
paper,
recycling
that
some
reprocessing
Glass
of
W
aste
the
it
materials
recycle
Remember
physical
(e.g.
used
useful
landll.
can
is
recycling.
Examples of
metals
and
materials
(e.g.
of
potentially
materials,
material
recycling
Make
processing
of
incineration
Recyclable
Exam tips
the
waste
glass
can
be
sorted
then
melted
and
either
used
to
make
new
glass
material.
objects
up
to
or
added
30%
as
energy
glass
saving
‘cullet’
and
a
to
glass
20%
being
reduction
freshly
in
made.
There
emissions
CO
can
made
be
by
2
recycling
glass
carbonate.
174
compared
with
making
glass
from
sand,
lime
and
sodium
Chapter
Recycled
glass

to
make

as
an

as
a

as
an
can
new
be
in
component
abrasive,
Chemistry
and
the
environment
used:
glass
aggregate
14
bottles
or
concrete
of
e.g.
glass
or
astroturf
in
for
display
making
and
counters
new
golf-bunker
ceramics
‘sand’
glasspaper
.
Paper
Recycled
paper
household
in
the
cut
world,
down.
water
can
waste.
so
paper
from
is
is
paper
about
35%
used
scrap
production
recycling
Recycling
pollution
Recycled
come
Paper
to
from
important
reduces
to
35%
the
making
quality
or
of
from
the
by
of
about
paper
paper,
trees
number
emissions
with
lower
mills
for
reduce
carbon
compared
make
paper
accounts
felled
trees
75%
from
and
trees.
cardboard
and
paperboard.
Plastic
Most
of
the
plastics
recycled
are
thermoplastics
–
those
that
melt
when
heated.
Recycling
making
the
plastic
plastic
same
type
recyclable.

PET
plastic
a
type
polyester
bins
HDPE
(high
plastic
furniture.
and
density
Poly(styrene)
picture
again.
The
by
Many
recycled
terephthalate))
of
rubbish
emissions
monomers.
about
70%
plastics
plastics
are
compared
not
formed
with
recycled
are
into
often
not
are:
(poly(ethene
bottles,

of
carbon
their
Examples
produce

reduces
from
can
bre
containers
used
plastic
recycled
to
are
melted
fabrics,
new
and
recycled
to
containers,
furniture.
poly(ethene))
be
for
is
recycled
make
clothes
to
make
rulers
hangers,
and
ower
pots
and
frames.
Steel
Scrap
and
iron
cast
girders.
and
The
steel
steel
and
iron
steel
pipes
iron
or
reduces
from
from
can
steel
carbon
haematite
steel
be
plates,
used
is
to
beams,
make
melted
and
emissions
by
new
columns,
steel
added
about
to
a
60%
old
car
products
furnace.
bodies,
such
as
Recycling
compared
with
iron
making
ore.
Key points

Waste
reduction
is
the
Did you know?
prevention
Some
archaeologists
down
scrap
bronze
have
or
suggested
other
that
metals, for
some
ancient
example, from
civilisations
old
axe
being
melted
heads, for
reuse.

the
for
Aluminium

Scrap
aluminium
aluminium
window
and
cans
frames,
added
to
a
from
is
aircraft
used
roong
furnace
to
fuselages,
make
and
then
new
car
bodies,
aluminium
aluminium
cans.
degassed
remove
to
cycles,
products
The
cookware
such
aluminium
hydrogen.
It
is
is
Recycling
aluminium
reduces
carbon
emissions
by
95%
consumption
of
as
by
95%
compared
with
making
used
use
purpose
is
something
sometimes for
and
sometimes
purpose.
the
processing
materials
into fresh
products.
melted
then
Describe
how
to
reduce
the
use
and
aluminium
materials
such
as
glass,
paper,
from
plastic,
bauxite
to
once,
different
Recycling
of
energy
material
and

recast.
means
than
same
a
waste
created.
Reuse
more
of
steel
and
aluminium.
ore.
175
14.
11
Solid
waste
Learning outcomes
completion
of
this
section,
be
able
avoid
too
describe
wastes
the
on
impact
the
glass,
solid
plastic,
reference
and
biodegradable
materials
before
non-
it
Some
and
and
waste
the
environment,
possible
(see
we
should
Section
generate
14.10).
The
the
options
and
heat
improper
techniques for
including
or
in
shown
in
recycled
the
Figure
but
we
14.11.1.
may
be
Much
able
to
of
get
our
solid
energy
from
ground.
steam
waste
can
gaseous
of
to
for
be
burnt
products.
its
in
This
original
run
a
special
can
volume.
turbine
disposing
of
incinerators
reduce
to
the
The
produce
some
to
energy
of
a
waste
solid
solid
released
electricity.
hazardous
form
volume
This
such
residue
waste
can
be
method
as
to
up
used
to
to
is
biological
and
disposal
dumps
waste.
One
problem
with
this
method
is
that
organic
compounds
and
such
sanitary
to
waste
are
reused
dumped
one-thirtieth
proper
materials
is
be
Incinerating
medical
of
solid
management
cannot
practical
disposal
damage
of
to
lead,
waste
describe
waste
waste
it
paper,
biodegradable
nuclear

of
terrestrial
environment. With
iron,
much
amount
to:
for

environment
you
smallest
should
the
Introduction
T
o
On
and
as
dioxins,
furans
and
polyaromatic
hydrocarbons
are
formed.
These
landlls.
are
toxic
waste
and
may
(heating
temperature)
containing
best
it
in
CO
stay
in
under
sealed
and
the
atmosphere
pressure
solid
which
H
with
vessels
is
for
many
limited
can
burnt
be
to
years.
oxygen
used
to
produce
at
a
make
Pyrolysis
of
high
carbon
and
a
gas
electricity.
2
prevention
Solid
waste
and the
environment
reuse
Solid
waste
may
harm
organisms
as
well
as
the
environment.
recycling
Glass:
energy
and
recovery
Broken
animals.
It
particles
of
glass
does
is
not
glass
sharp
and
degrade
are
may
very
produced.
cause
quickly.
These
cuts
and
When
may
abrasions
glass
remain
in
breaks,
the
air
in
tiny
for
some
disposal
worst
time
option
and
lenses,
Fig 14.11.1
Options for waste management
Paper:
soil
Printing
as
wind,
so
get
lungs.
as
Did you know?
and
of
the
a
waste
in
the
sea
by
may
be
as
million
kg
of
much
plastic
be
gets
a
of
glass
leading
meals
and
such
to
as
substances
paper
is
easily
can
also
act
as
res.
cadmium
organochlorine
toxic
addition
danger
stuck
dies.
action
in
In
Pieces
heating
heavy
bleaches
potentially
plastic
of
nets
in
wildlife,
and
compounds
may
leach
blown
gullet,
leach
readily
and
down
and
into
few
are
they
and
years.
sh
from
sea
the
animal
from
out
they
plastics
a
when
the
microorganisms),
after
especially
suffocate
organisms
also
Biodegradable
seas
to
or
the
Many
may
decompose
creatures
cause
contain
wet.
lungs.
into
away
by
in
the
the
litter
.
in
break
the
cannot
to
the
not
in
the
are
many
(break
environment
materials
plastics,
which
the
any
Since
biodegradable
biological
particles
into
ingest
crocodiles
Biodegradable
microscopic
Animals
gets
plastics.
remain
other
life.
plastic
may
such
however
,
be
harmful
rivers.
is
in
Many
metals
are
alloys.
When
they
are
thrown
away,
they
may
as
react
10 000
do
of
and
decompose
time.
simply
Metals:
plastic. There
gets
additive
not
the
long
may
These
therefore
T
oxic
rays
residual
can
plastic
do
wood
may
to
80%
These
If
plastics
for
paper
tangled
affected.
down
inks
as
spreading
Plastics:
food
well
irritation
light
quantities.
when
may
cause
focusing
arsenic
small
can
with
water
and
air
and
corrode
to
form
soluble
compounds
which
the
diffuse
into
the
soil
or
water
.
Iron
rusts
and
may
form
unsightly
pools
of
oceans.
red
waste
metals
from
This
and
176
which
such
as
lead
aluminium
waste
reduce
with
growth
cadmium
smelting
reacts
hydrogen.
or
plant
may
water
as
(from
still
well
car
being
batteries)
contain
forming
as
high
ammonia
unsightly.
are
poisonous.
amounts
and
Some
of
W
aste
aluminium.
ammable
acetylene
Chapter
Nuclear
waste:
This
may
contain
radioactive
isotopes
with
very
long
14
Chemistry
and
the
environment
half
129
lives,
cause
as
I
e.g.
has
radiation
well
as
a
half
burns,
causing
Disposing of
life
of
skin
animals
solid
17
million
damage
to
and
become
years.
Radioactive
damage
to
the
waste
immune
may
system
sterile.
waste
Landll
W
aste
Some
can
poorly

be
buried
landlls,
a
landll
site
however
,
consist
of
managed
Wind
can
in
site
blow
may
away
create
paper
a
such
as
mounds
number
and
an
of
of
plastic
unused
rubbish
quarry
(waste
environmental
bags
into
the
or
mine.
dumps).
A
problems:
surrounding
areas.
waste

T
oxic
or
harmful
liquids
may
drain
through
the
soil
or
rocks
gas
to
cover
contaminate

Gases
such
released
as
groundwater
as
a
methane,
result
of
and
soil.
carbon
organic
dioxide
waste
and
hydrogen
breaking
down
in
sulphide
the
are
absence
of
solid
oxygen.
Some
of
these
gases
are
foul-smelling
and
may
kill
wastes
surface
rock/
vegetation.
Others
(methane
and
)
CO
are
greenhouse
lining
gases.
2
soil

Organic

W
aste
material
may
attract
rats
and
other
vermin.
Figure 14.11.2
of
In
a
the
dumps
may
rubbish
can
well-managed

The
waste

The
site
is
has
take
up
large
area
and
be
unstable
because
landll
(sanitary
lining
of
to
landll)
prevent
clay,
it
plastic
site:
moving
or
or
blowing
rubberised
Did you know?
away.
material
which
Nuclear
minimises
drainage
of
liquids
into
the
soil
or
rocks
The
gases
are
extracted
(the
gases
are
either
burnt
waste
can
off
immediately
used for
other
137

burnt
The

site
is
Because
smaller
in
it
a
controlled
covered
is
so
way
that
compacted,
it
to
generate
does
the
not
waste
is
reprocessed
purposes.
For
or
example,
are
be
below.
and

A modern landll site
some
move.
compacted
a
a
90
Cs
and
Sr
can
be
electricity).
attract
more
rats
stable
and
and
other
separated from
other
substances
and
used
food
bacteria.
radioactive
vermin.
conned
to
a
to
kill
to
irradiate
area.
Composting
Organic
plant
material
and
animal
waste
can
be
composted
and
returned
Key points
to
the
soil
materials
as
in
a
fertiliser
.
the
Fungi,
presence
of
bacteria
and
worms
help
break
down
the
oxygen.

Iron,
glass,
metals
Nuclear
waste
plastic,
may
all
environment
if
paper
harm
not
and
the
disposed
of
correctly.
This
requires
completely
the
special
isolated
methods
used
treatment
and
cannot
so
that
escape
the
into
radioactive
ground
substance
water
or
air
.
is
Amongst

are:
Incineration
energy
solid

Vitrication:
allowed
glass

is
to
stored
Adsorption:
waste
which
The
cool.
to
is
waste
The
in
steel
Iron( iii)
adsorb
mixed
is
glass
heated
does
cylinders
hydroxide
and
with
in
or
concentrate
cement
then
not
safe
an
the
then
mixed
dissolve
with
or
places
solution.
into
with
glass
water
.
A
resin
sludge
drums
and
is
is
going
of
waste
reduce
to
can
the
provide
amount
of
landll.
and
The

underground.
ion-exchange
put
molten
react
and
A
good
landll
drainage
added
to
loss
the
formed
of
of
site
liquid
will
to
greenhouse
prevent
the
soil
gases
to
and
the
air.
stored

Nuclear
waste
can
be
disposed
underground.
of

Above
ground
disposal:
(Low
level
waste).
The
waste
is
put
into
a
by
vitrication
followed
cylinder
.
An
inert
gas
is
added.
The
steel
cylinder
is
then
placed
or
adsorption
steel
in
by
encasement
in
a
cement.
concrete
cylinder
and
stored.
177
Exam-style
Answers to
all
exam-style questions
can
questions
be found on the
–
Module
accompanying CD
iv
Multiple-choice questions
To
separate
hydroxide
1
Which
the
of
the following
reaction
electrolysis
which
of
half
occurs
equations
at
the
Al(l)
Al
(aq)
→ Al
(aq)
C
Al(l)
+
brine
used from
the
sodium
cathode
during
A
i
only
produced.
B
i
and
C
i,
ii
D
i,
ii,
the
ii
only
alumina?
+
3e
and
iii
only
3e
3+
B
the
represents
3+
A
3
iii
and
iv
→ Al(l)
3+
(l)
→ Al
+
3e
6
During
the Contact
Process,
sulphur
trioxide
is
3+
D
2
Al
(l)
Which
of
emitted
+
3e
→ Al(l)
the following
into
the
are
pollutants
atmosphere
during
that
the
produced
by
shown
the following
by
rening
carbon
hydrogen
iii
oxides
2SO
(g)
+ O
(g)
Y
equation:
2SO
2
(g)
∆H
=
–196 kJ mol
3
of
the following
of
in
the
yield
iv
chlorofluorocarbons
A
i
and
iii
only
Low
B
i
and
iv
only
C
i,
ii
D
i,
iii
B
and
iii
and
temperature,
High
C
Low
only
iv
is
D
manufactured
combining
this
nitrogen
reaction
is
during
and
shown
the
Haber
+
3H
2
(g) Y
hydrogen. The
equation
7
below:
2NH
2
High
of
a
maximum
trioxide?
pressure
and
high
(g)
∆H
The
is
=
of
of
concentration
crucial
low
pressure
and
low
and
low
and
high
oxygen.
high
pressure
oxygen.
low
pressure
oxygen.
Which
to
of
the
of
dissolved
existence
the following
of
oxygen
aquatic
causes
a
in
water
life forms.
decrease
in
the
–92 kJ mol
represents
the
temperature
and
of
dissolved
oxygen
in
water
bodies?
ideal
A
of
of
3
the following
conditions
high
temperature,
concentration
Which
produce
Process
–1
(g)
would
sulphur
oxygen.
temperature,
concentration
only
of
temperature,
concentration
concentration
Ammonia
of
nitrogen
concentration
N
pressure for
Low
temperatures
and
an
increase
in
aerobic
the
respiration.
production
of
ammonia
using
this
process?
B
A
Low
temperature
and
high
High
temperatures
and
an
increase
in
aerobic
pressure.
respiration.
B
High
C
Low
temperature
and
low
pressure.
C
temperature
and
low
Low
temperatures
and
a
decrease
in
aerobic
pressure.
respiration.
D
High
temperature
and
high
pressure.
D
4
Which
of
the following
production
of
are
necessary for
ethanol from
High
the
temperatures
and
a
decrease
in
aerobic
respiration.
the fermentation
of
8
A
yellow
precipitate
was
produced
when
a
sample
sugars?
of
A
Carbon
dioxide,
yeast
and
river
water
B
Aerobic
conditions,
C
Anaerobic
yeast
and
tested
by
adding
iodide
yeast
of
the following
pollutants
is
and
in
this
sample
of
water?
water.
A
NO
B
PO
ions
3
Carbon
dioxide,
anaerobic
conditions
and
yeast.
3–
ions
4
5
During
the
the
production
diaphragm
What
is
cell,
a
of
chlorine from
porous
brine
diaphragm
is
using
To
C
CN
D
Pb
used.
ions
2+
ions
its function?
9
i
separate
the
liberated
hydrogen
and
Which
of
the following
gases.
To
separate
sodium
iii
To
178
liberated
hydroxide
separate
sodium
the
the
gas from
hydrogen from
produced.
A
RCl
B
O
C
Cl•
D
ClO•
the
produced.
liberated
hydroxide
chlorine
species
reacts
with
chlorine
stratospheric
ii
ions
most
water.
present
conditions,
was
to
water.
it. Which
D
as
sulphide
A
for
oxygen
monoxide
ii
by
with
–1
of
increase
3
dioxide
oil?
Which
i
sulphur
are
2
crude
reacting
2
the
ozone
causing
its
depletion?
likely
Module
10
Fires
are
waste
a
in
major
produced from
A
hazard
when
landlls. Which
landlls
of
is
disposing
of
the following
responsible for
solid
d
gases
Why
are
being
these res?
e
O
hydrogen
allowed
to
and
3
Exam-style
nitrogen
questions
puried
before
react?
[1]
Suggest ONE reason why the ammonia is removed
from the system as soon as it is formed?
[2]
2
B
CO
f
State
ONE
use
of
ammonia
in
EACH
of
the
2
following
C
H
D
CH
industries:
2
i
Agriculture
[1]
ii
Chemical
[1]
4
Structured questions
13
11
Aluminium
is
extracted
by
the
electrolysis
of
The chlor-alkali industry refers to the industrial
molten
production of the alkali sodium hydroxide and chlorine
aluminium
oxide. This
oxide
is found
in
bauxite
along
by the electrolysis of a concentrated solution of
with
oxides
of
iron
and
silicon
which
are
the
main
sodium chloride (brine). One method of production
impurities.
involves the use of the diaphragm cell as shown below.
a
Write
the formulae for
the
chlorine
i
iron
ii
silicon
found
and
as
hydrogen
+
oxides
impurities
in
aluminium
oxide.
[2]
A
b
i
State
the
silicon
ii
Use
in
acid–base
a
your
how
oxide
an
of
the
oxide
of
above.
answer
this
include
i
nature
is
ionic
[1]
in
b
i
above
to
explain
removed from
equation
in
the
your
bauxite,
E
explanation.
C
[4]
c
Explain
why
aluminium
and
describe
electrolytic
d
i
dissolving
oxide
Write
how
the
Explain
cryolite
in
economically
it
achieves
this
the
benet
in
half
State ONE
property
for
Complete
ii
Describe
equation for
the
anode.
why
the
anode
the
in
reaction
iii
[2]
must
be
property
periodically
aluminium
packaging food
that
and ONE
allows
it
to
iv
Ammonia
by
is
manufactured
[2]
combining
nitrogen
and
during
the
Haber
+
3H
2
(g) Y
2NH
2
How
is
the
are
produced
cell.
[5]
the
reaction
anode.
[2]
Carbon is not used to make the anode (B) and
Why
is
the
diaphragm
environmental
used
in
this
particular
[3]
cell,
hazard?
[1]
c
State
a
Using
ONE
use
of
chlorine.
[1]
hydrogen.
(g)
∆H
=
14
balanced
equations
explain
how
the
–92 kJ mol
3
concentration
a
chlorine,
Process
–1
(g)
N
which
hydroxide
equation for
the
[3]
from and explain why carbon is not used.
b
an
12
E
materials that the anode and cathode are made
used
products.
half
at
by
sodium
diaphragm
the
and
the cathode (D) in this particular cell. State the
physical
be
Write
process
and
occurring
[2]
chemical
the
labels A, C
the
hydrogen
[2]
at
of
i
the
replaced.
e
a
molten
benecial
process.
occurring
ii
is
nitrogen for
the
Haber
of
ozone
is
maintained
in
the
Process
stratosphere.
obtained?
b
b
i
State
[5]
[1]
the
source
of
the
hydrogen
used
in
i
Using
the
data
below,
describe
the
trend
in
the
the
Process.
concentration
of
stratospheric
ozone
over
[1]
time.
ii
Write
TWO
hydrogen
is
equations
to
show
obtained from
the
how
[1]
the
source
Year
mentioned
c
i
State
used
the
to
in
b
i
above.
temperature
manufacture
and
pressure
ammonia
that
using
[O
are
]

Why
iii
the
temperature
Explain
stated
in
your
c
i
above
is
2000
260
240
160
110
108
why
the
trend
described
in
b
i
above
Using
considered
to
be
a
the
concern.
is
relevant
[2]
equations,
explain
why
the
answer
trend
in
1990
[2]
cause for
Explain:
1980
the
Process.
ii
1970
3
ii
Haber
1960
[4]
described
in
b
i
is
occurring.
[4]
compromise
iv
Outline
ONE
prevent
this
step
that
can
be
taken
to
temperature.

Why this compromise temperature is used.
trend from
continuing.
[1]
[2]
179
Data
Selected
sheets
bond
energies
Selected
electrode
potentials
Ø
Diatomic
molecules
Polyatomic
molecules
–1
Electrode
–1
Bond
436
C—C
350
Mg
N≡N
994
C=C
610
Al
O=O
496
C—H
410
V
F—F
158
C—Cl
340
Zn
Cl—Cl
244
C—Br
280
Fe
Br—Br
193
C—I
240
V
I—I
151
C—N
305
Ni
H—F
562
C—O
360
Sn
H—Cl
431
C=O
740
Pb
H—Br
366
N—H
390
2H
Bond
H—H
energy/kJ mol
energy/kJ mol
E
/V
+
Bond
Bond
reaction
+
K
e
Y
K
–2.92
2+
+
2e
Y
Mg
–2.38
3+
+
3e
Y Al
–1.66
2+
+
2e
Y V
–1.2
2+
+
2e
Y
Zn
–0.76
2+
+
2e
Y
3+
Fe
–0.44
2+
+
e
Y V
–0.26
2+
+
2e
Y
Ni
–0.25
+
2e
Y
Sn
–0.
14
+
2e
Y
Pb
–0.
13
2+
2+
+
+
2e
Y
H
0.00
2
2–
H—I
299
N—N
160
O
S
4
2–
+
2e
Y
2S
6
O
2
+0.09
3
2+
O—H
460
Cu
+
O—O
150
VO
2e
Y Cu
2+
+0.34
+
+
2H
3+
+
e
Y V
+
H
O
+0.34
2
+
I
2e
Y
2I
+0.54
2
3+
2+
+
Fe
e
Y
Fe
+0.77
+
+
Ag
e
Y Ag
+
+0.80
+
+
VO
2H
2+
+
e
Y VO
+
H
2
+
Br
O
+1.00
2
2e
Y
2Br
+1.07
2
2–
O
Cr
2
+
Cl
+
+
14H
3+
+ 6e
Y
2Cr
+
7H
7
O
+1.33
2
2e
Y
2Cl
+1.36
2
–
4
180
+
+
MnO
8H
2+
+
5e
Y
Mn
+
4H
O
2
+1.52
sheets
Data
0.571
301
rL
muicnerwal
]262[
0.371
201
oN
muilebon
]952[
9.861
101
dM
muivelednem
]852[
3.761
001
mF
muimref
]752[
9.461
99
sE
muinietsnie
]252[
5.261
89
fC
muinrofilac
]152[
9.851
79
kB
muilekreb
]742[
3.751
69
mC
muiruc
]742[
0.251
59
mA
muicnema
]342[
4.051
49
uP
muinotulp
]442[
]541[
39
pN
muinutpen
]732[
2.441
29
U
muinaru
0.832
9.041
19
aP
muinitcatorp
]132[
eC
munec
1.041
09
hT
munoht
0.232
901
tM
muirentiem
]86 2 [
muimso
2.091
801
sH
muissah
]962[
muinehr
2.681
701
hB
muirhob
]462[
netsgnut
8.381
601
gS
muigrobaes
]662[
mulatnat
9.081
501
bD
muinbud
]262[
fH
muinfah
5.871
401
fR
muidrofrehtur
]162[
75
aL
munahtnal
9.831
98
cA
muinitca
]722[
65
aB
muirab
3.731
88
aR
muidar
]622[
74.58
55
sC
muiseac
9.231
78
rF
muicnarf
]322[
85
rP
muimydoesarp
muidiri
2.291
aT
27
95
dN
muimydoen
1.591
W
37
06
mP
muihtemorp
munitalp
eR
47
16
mS
muiramas
dlog
0.791
sO
57
26
uE
muiporue
yrucrem
6.002
rI
67
36
dG
muinilodag
muillaht
4.402
tP
77
46
bT
muibret
dael
2.702
uA
87
56
yD
muisorpsyd
htumsib
0.902
gH
97
66
oH
muimloh
]902[
lT
08
76
rE
muinolop
bP
18
86
muibre
]012[
iB
28
96
mT
muiluht
enitatsa
oP
38
07
bY
muibretty
nodar
]222[
tA
48
17
uL
muitetul
nR
58
73
bR
68
rS
01.93
muidibur
83
26.78
Y
80.04
muitnorts
93
muirtty
rZ
69.44
19.88
04
22.19
bN
78.74
muinocriz
14
muiboin
oM
49.05
19.29
24
49.59
cT
00.25
munedbylom
34
]89[
uR
49.45
muitenhcet
44
1.101
hR
58.55
muinehtur
54
9.201
dP
39.85
K
muissatop
muidohr
64
aC
muiclac
4.601
gA
96.85
cS
muidnacs
muidallap
74
iT
muinatit
revlis
dC
55.36
V
muidanav
9.701
84
rC
muimorhc
4.211
nI
93.56
nM
esenagnam
muimdac
94
nori
muidni
nS
27.96
eF
8.411
05
oC
tlaboc
nit
bS
16.27
iN
lekcin
7.811
15
uC
reppoc
8.121
eT
29.47
cniz
ynomitna
25
nZ
6.721
I
69.87
aG
muillag
muirullet
35
eG
muinamreg
enidoi
eX
09.97
sA
cinesra
9.621
45
eS
muineles
nonex
0 8 . 38
rB
enimorb
3.131
rK
notpyrk
13.42
02
210.9
muihtil
149.6
3
iL

eB

4
muillyreb
11
91
99.22
12
92

22
03
  
cimota
21
32
13

42
23

52
33

62
43
89.62
72
53
90.82
82
63
79.03
evitaler

70.23
aN
muidos
yeK
)notorp(
cimota
eman
cimota
rebmun
lobmys
ssam

54.53
gM
muisengam
800.1

59.93
lA
muinimula
31
iS
nocilis
41
P
surohpsohp
norob
18.01
51
S
nobrac
10.21
61
ruhplus
10.41
71
lC
enirolhc
negortin
81
rA
nogra
negyxo
B
00.61
C
eniroufl
N
5
00.91
O
6
noen
F
7
81.02
eN
8

9

  
negordyh

01
muileh
1
H

300.4
2
eH

181
Glossary
-1
Band
region
The
Chromatography
1300–3000 cm
Method
of
separatng
A
waenumber
Absorbance
absorbed
Accurate
ery
Acid
by
a
percentage
close
to
(%)
ther
acdc
oxdes SO
Addition
n
reaction
and
NO
A
sngle
and
product
other
Adsorption
bonds
Air lter
a
dust
gases
power
and
s
Base
ths
peak
of
regon
tallest
path
used
to
plants
Mode
one
or
more
Aldehyde
A
compound
—OH
Aliphatic
chans
formula C
Brine
that
wth
A
a
bonds
s
s
concentraton
one
up
of
and
smplest
and
of
the
down
n
relate
a
to
ols
engnes
made
and
has
of
the
but
and
(gen
atom
not
the
compounds
reaction
and
When
a
small
showng
the
n
Alternative fuels
more
cleanly
reduce
Amide
carbon
An
CONH
Fuels
than
whch
burn
hydrocarbons
an
To
aqueous
atoms
measurement
emssons.
organc
soluton
or
wth
the
readngs
those
of
of
a
effect
molecules
lengths
Contact
by
standards.
functonal
hang
a
group.
NH
An
organc
functonal
compound
hang
an
group.
acid
hang
An
an
organc
NH
compound
functonal
chan,
R,
whch
group
can
be
Carbocation
postely
group,
of
a
n
2
COOH functonal
and
a
acdc,
sde
C,
for
alkalne
C
or
wth
and
and
Occurs
multple
effect
cyclc
rngs
delocalsed
that
wth
hae
one
or
delocalsed
n
n
some
bond
the
e.g.
bond
strengths
between
boiling
bonds,
ordnary
double
mixture
sngle
bonds.
See
mxture.
Process
ths
Sulphurc
process,
whch
of
a
relates
of SO
substance
e.g. UV
to SO
a
carbon
atom
s
O
made
the
usng
a V
3
O
2
temperature
a
The
salt wth
phenol to form
Cracking
The
nto
450
reacton of
an
alkalne
an
thermal
of
5
C.
a
soluton
azo dye.
decomposton
shorter-chan
alkanes
of
and
alkenes.
molecule
where
2:1. The
smple
a
Coupling reaction
alkanes
charged.
A
and
dazonum
organc
s
to
o
catalyst
of
n
acd
refers
the
consstng
H
and
general
O
are
formula
carbohydrates
Cryolite
Compound
alumna
durng
and
the
lower
used
ts
to
dssole
meltng
electrolyss
of
pont
alumna.
s
O)
2
y
cycle
through
water
Compounds
rng
structure
that
based
hae
on
benzene.
and
A
mxture
that
of
wdely from
Raoult’s
law
whch
carbon
acid
A
n
cracking
of SO
Catenation
The
lng
keeps
the
ar
the
and Al
contanng
usng
a
A
remoed
Delocalised
can
more
reacton
Electrons
oer
whch
two
Denitrication
whose
three
moement
than
n
water
(elmnated).
extend
allowng
O
2
Dehydration
s
group.
Crackng
ablty
thngs,
constant.
compound
the COOH functonal
catalyst
and
carbon
atmosphere,
rocks
of
Carboxylic
Catalytic
mixture
The ow
the
2
deates
whch
ntermedate
where
rato
amount
compounds
Azeotropic
changes
makes
ordnary
conerson
cure
property,
An
and
most
(H
Carbon
Compounds
electrons.
Aryl
Ttratons
of
D
neutral.
more
H
the
x
Aromatic
A
concentratons
partcular
Carbohydrate
2
Amino
a
chemstry
2
Amine
to
curve
absorbance.
compound
attached
conductty.
ntermedate
correlate
nstrument
known
and
an
bonds.
Conductimetric titrations
azeotropc
Calibration
2n
of
each
C
standard
H
two
off ).
2
general formula C
or
molecule
A formula
compound
Constant
the
geometrc
mxture.
react
benzene. The
or fats.
chlorde.
general
one
a
elmnated
Conjugative
desel
concentrated
sodum
solublty
6
chans.
contans
One
n
electrcal
aromatc
See
Condensed formula
carbon
a
atoms
H
A fuel for
Calibrate
double
soluton
bonds
2n+2
that
Component
molecules
of
contan
the
isomerism
elements
mass
n
somersm.
nolng
The
Biodiesel
of
branched
Hydrocarbon
more
a
H
n
or
or
Hydrocarbon
Alkene
contanng
molecule.
a
amount
of braton
from egetable
group.
Compounds
carbon
Alkane
has
groups.
compound
CHO functonal
that
n
as
dfferences
charge.
organc
where
hydrocarbon, C
Alphatc
The
the
6
Alcohol
the
such
other.
Benzene
statons.
by
to
bond brates
the
and
n
peak
cis-trans
the
groups
length.
molecule
Apparatus
and/or
by
Condensation
law
absorbed
Bending
partculates from
ndcate
and C=O
The
compounds
the
spectrum. Specc
partcular
proportonal
the
of formng
of
spectrum.
lght
molecules
surface.
chemcal
n
presence
Beer–Lambert’s
s formed.
process
sold
n
whch
product
reactant
(industrial)
remoe
waste
The
wth
,
2
two
electromagnetc
C—H, O—H
produces
ranwater.
formed from
no
are
true alues.
Burnng fossl fuels
deposted
lght
peaks
measurements
2
are
of
soluton.
Accurate
rain
the
The
regon
or
of
orbtals
more
atoms,
electrons
oer
atoms.
The
reducton of
ntrates
3
of
carbon
atoms
to
N
gas
by
bactera.
2
has
a
maxmum
pont. Also
or
called
mnmum
a
constant
bolng
bolng
mxture.
to form
Chain
the
chans
by
isomerism
jonng.
The
arrangement
of
Desalination
somers
the
dffer
carbon
n
atoms
water,
The
remoal
usually from
Diazonium
salt
A
of
salts from
seawater.
salt
of
general
+
Azo dye
The
reacton
wth
an
dye formed
between
alkalne
a
by
a
couplng
dazonum
soluton
of
a
salt
phenol.
n
ther
Chiral
carbon
centre
wth four
t,
A
skeleton.
carbon
dfferent
creatng
the
somers. Some
(or
formula
other
groups
possblty
atom)
attached
of
molecules,
to
optcal
e.g.
glucose,
RN
Diazotisation
dazonum
aromatc
≡NX
The formaton
salt
by
amne
the
wth
Displayed formula
of
a
reacton
ntrous
A formula
of
an
acd.
showng
B
hae
Back titration
reagent
soluton
reagent
182
s
to
s
A
known
added
be
n
amount
excess
to
estmated. The
then
ttrated.
of
the
excess
more
than
one
Chlorofluorocarbons
contanng C, Cl
responsble for
layer.
chral
centre.
(CFCs)
and
F
that
depletng
Molecules
are
the
ozone
all
the
atoms
Distribution
bonds.
coef cient
equlbrum
dstrbuton
mmscble
and
constant
of
solent
solutes.
The
for
the
between
two
Glossary
Initiation
E
The rst
photochemcal
Electrodialysis
where
ons
soluton
Method
are
to
step
n
a
G
of
desalnaton
transported
another,
usng
from
one
Gas–liquid chromatography
radcals
Chromatography n whch the
Iodoform
statonary phase s a lqud and the
an
reacton
n
whch free
are formed.
reaction
contanng
Compounds
CHOH
the CH
group
are
3
on-exchange
moble phase s a gas.
membrane.
oxdsed
by
and
I
NaOH
to form
a
2
Electromagnetic
whch
hae
radiation
electrcal
Geometrical isomerism
Waes
and
groups ether sde of a double bond are
magnetc
arranged ether on the same sde (cis) or
components.
Electrophile
partally
that
a
A
postely
postely
attacks
an
charged
charged
on the opposte sdes (trans).
or
reagent
electron-rch
area
of
Global warming
yellow
Isomers
Molecules
formula
Formula
arranged
smplest
rato
of
atoms
of
n
the
that
hae
but
the
the
same
atoms
are
dfferently.
The rse n temperature
K
Determnng the
A
compound
contanng
a CO
amount of a substance present n a
each
functonal
element
trodomethane.
of the atmosphere due to the
Gravimetric analysis
showng
of
molecular formula
Ketone
the
precptate
greenhouse effect.
molecule.
Empirical
Two substtuent
group
between
two
carbon
compound by methods nolng
compound.
atoms.
Ester
Compound
contanng
weghng.
the
Greenhouse effect
O
The process by whch
thermal radaton s absorbed by the
functonal
C
O
C
M
group.
C
atmosphere and re-radated n all
M + 1
peak
Small
peak
n
a
mass
drectons.
spectrometer
Esterication
The
reacton
of
an
Greenhouse gas
wth
a
carboxylc
acd
to
the
an
molecular
Eutrophication
The
polluton
of
rers
leadng
to
the
death
ratio
The process for makng
and H
2
Mass
usng an ron
2
catalyst.
F
Alkane n whch one or
more H atoms are substtuted by
A
soluton
dstngush
aldehydes
The breakng of a
bond so that the two shared electrons
n the bond are splt unequally between
Fermentation
(alcoholic )
Makng
the two atoms. One of the atoms keeps
from
sugars
by
usng
yeast
both the electrons and so becomes
anaerobc
condtons
(no
becomes postely charged.
See
ar
region
The
Homologous series
A group of organc
regon
600–1300 cm
of
spectrum.
Peaks
n
unt.
ncreases by a CH
regon
tell
us
about
the
whole
The breakng of a bond
molecule.
so that the two shared electrons n the
Fraction
A
group
of
compounds
that
bond are splt equally between the two
separate
from
a
mxture
wthn
a
atoms, one electron gong to each atom.
narrow
range
of
bolng
ponts.
Hybridisation
Fractional
distillation
A
process
The process of mxng
separate
mxtures
of
lquds
used
dfferent
bolng
Compounds contanng
The
breakdown
of
a
n
a
Hydrolysis
compound
n
a
partcular
way
as
of
cars.
the
data
n
numbers
dentcal
experments.
Mesomerism
oer
Makng
from
liquids
one
up
seeral
a
composte
dfferent
Lquds
able
to
mx
another.
phase
the
Molecular
the
The
phase
statonary
formula
actual
element
that
phase
moes
n
present
ion
formula
of
n
peak
arsng
electron
Monomer
The breakdown of a
A
number
a
atoms
showng
of
molecule
each
of
a
compound.
one
ponts.
carbon and hydrogen only.
Fragmentation
such
transportaton
nddual
the
masses
compounds.
ehcles
for
aerage
spectrum
of
Hydrocarbons
slghtly
trans
from
Molecular
used
atomc orbtals.
to
on
chromatography.
2
structure
Homolytic ssion
the
taken
Mobile
the
group n whch each successe member
electromagnetc
of
an
atomc
organc
Usng
than
The
wth
compounds wth the same functonal
waenumber
ths
of
m/z
Instrument
relate
dentfy
and
Miscible
lter.
–1
Fingerprint
charge
structures.
present).
(industrial)
to
transit
structure
negately charged. The other atom
Filter
Mass
Mean
from
ketones.
oxygen
ts
spectrometer
rather
used
Heterolytic ssion
under
by
calculate
buses
halogen atoms.
solution
to
and
Halogenoalkane
ethanol
mass
mass
anmals.
ammona from N
to
In
the
of
Haber Process
and
Fehling ’s
unt
peak.
H
dded
fertlsers
plants
on
ester.
spectrometry,
by
m/z
emts nfrared radaton.
Mass/charge
make
one
A gas that absorbs and
beyond
alcohol
trace
from
Small
together
to
The
from
a
peak
the
a
mass
of
molecule.
molecules
form
n
remoal
that
jon
polymers.
compound wth water. The rate of
mass
spectrometer.
reacton s often ncreased by reactng
Free
radical
Atoms
or
groups
of
atoms
N
the compound wth an acd or an alkal.
wth
an
unpared
Frequency
The
electron.
number
of
Nitration
waes
In
organc
chemstry,
the
I
passng
Fuel
cell
whch
a
gen
An
O
pont
per
electrochemcal
and
H
2
react
to
substtuton
second.
cell
atoms
Ideal
produce
s
group
that
ge
An
a
group
same
atom
Raoult’s
group
of
ts
propertes.
isomerism
formula
but
or
compound
chemcal
molecular
the
H
atom
by
an
A
soluton
whch
NO
group.
obeys
Nitrogen cycle
law.
The ow of ntrogen
2
partcular
The
solution
Immiscible
Functional
a
2
n
water.
Functional
of
the
of
the
functonal
dssole
Inductive
atoms
or
somers
groups
liquids
n
each
effect
to
exert
around
a
an
do
not
effect
of
groups
on
the
of
electrons
atom.
Radaton
through the atmosphere, lng thngs,
water and rocks that keeps the amount
ablty
electron-attractng
partcular
(IR)
whch
other.
The
wthdrawng
Infrared
Lquds
of
waelength
of N
n the ar constant.
2
Nitrogen xation
The conerson of N
2
the ar to ammona by bactera.
Nucleophile
A reagent that donates a
par of electrons to an electron-
6
are
dfferent.
about
700–10
nm.
decent atom n a molecule.
183
n
Glossary
Nucleophilic substitution
A reacton n
Primary
pollutant
Pollutant
released
S
drectly from
whch the nucleophle bonds wth or
Primary
‘attacks’ the poste or partally
propertes
molecule (usually a carbon atom)
deducng
attached to t.
acds
process.
standard
poste charge of an atom n a
resultng n the replacement of a group
a
the
and
A
make
chemcal
t
Saponication
whose
soaps
sutable for
concentraton
of
other
A cyclc seres of reactons n
whch free radcals react wth molecules
or atoms to form dfferent radcals and
O
Proteins
Optical
isomerism
This
occurs
different
groups
are
polymers
made from
of
only
Compounds
sngle
hydrogen
Scrubber
usng
bonds
can
Part
a
be
of
so
that
that
a
central
carbon
and
a
of
more
added.
chemcal
partcles from
spray
contan
no
plant
waste
naturally
occurrng
amno
Secondary
that
gases
water.
acds.
(referrng
to
alcohols
and
attached
halogenoalkanes) The OH
to
makng
of fats
when
20
four
Natural
process
hydrolyss
ols.
remoes
dfferent molecules or atoms.
The
the
Saturated
alkals.
Propagation
by
atom. The
two
attached
to
a
carbon
attached
to
two
or Cl
atom
s
whch
s
Q
isomers formed
each
mirror
images
of
Quanta
other.
Ozone depletion
amount
caused
Ozone
are
of
The
ozone
n
decrease
the
n
ozone
the
an
layer
Energes
whch
can
be
of xed alues
absorbed
or
only,
emtted
Secondary
by
atom.
An
stratosphere
wthn
has
a
remoes
the
atoms.
Pollutant formed
pollutants
undergo
agent
Agent
partcular
whch
ons from
soluton
R
relately
or from
hgh
Radical
of
carbon
reactons.
Sequestering
area
that
concentraton
pollutant
prmary
further
by CFCs.
layer
when
other
See free
Solvent
law
The
partal apour
extraction
a
component
n
a
mxture
=
because
× apour
of
separaton
dfferences
n
of
a
ts
ts
solublty
mole fracton
The
pressure
solute
of
ar.
radcal.
ozone.
Raoult’s
the
pressure
n
two
solents.
of
Solvent front
The leadng edge of the
P
pure
component.
solent that progresses along the
Partial vapour
pressure
The
pressure
Reaction
mechanisms
These
show
the
surface where the separaton of the
exerted
by
each
component
n
the
steps
n
bond
breakng
and
bond
mxture (chromatography) s occurrng.
apour
alone.
makng
when
reactants
are
conerted
Standard deviation
Partition
coefcient
See
dstrbuton
to
ntermedates
and
then
to
spread
coefcent.
Recycling
The
processng
of
out
Ddng
the
components
materals
nto
new
a
mxture
between
two
dfferent
Redox titration
data
measure
s from
of
the
how
mean.
phase
In
chromatography,
a
products.
sold
of
the
used
Stationary
Partitioning
A
products.
These
are
used
or
lqud
that
remans xed
n
to
poston.
phases.
calculate
the
concentraton
of
Steam distillation
Phenol
Compound
contanng
one
or
oxdsng
or
reducng
olatle
more
—OH
to
aromatc
groups
attached
drectly
Reforestation
compound from
rng.
formed
when
smog
A
smoky fog
and
hydrocarbons,
ozone
usng
react
n
ntrogen
the
presence
absorbs more CO
Reforming
the
same
lght.
lght
Polyamide
The
breakng
(usually UV
Polymers
but
the
wth
of
a
Relative abundance
atoms
hae
n
lght).
many
Mode
Polymers
amde
brate
one
the
wth
many
unit
ester
atoms
n
a
monomer,
molecule
bult
The
smallest
group
up from
molecules.
n
the
polymer
whch
structure
Resonance
process
dered from
of
when
the
joned
of formng
hybrid
structure
of
a
monomers.
synthess
of
The
Polymer
of
smple
sugar
Retention time
In
unts.
the
isomerism
The
poston
of
tme
n
and
ts
a
a
smpled form.
isomers
same
Compounds
molecular formula
wth
but
made
up
of
structural formulae.
a
reaction
A
reacton
n
dfferent forms.
gas
between
compound
showng
n
ges
one
atom
or
group
of
atoms
s
chromatography,
replaced
Positional
atoms
composte
molecule
seeral
A formula
of
polymer.
whch
Polysaccharide
bond
a
Substitution
polymers from
a
a
plane.
arrangement
dfferent
The
of
n
of
the
Polymerisation
atoms
commonest speces n a mass spectrum.
Repeating
—COO—.
Large
small
dfferent
of braton
where
Structural
many
a
of one speces compared wth the
—CONH—.
lnkages,
hae
other
space.
molecule
molecule
Polymer
each
The relate amount
the
Polyester
to
from the ar.
Structural formula
lnkages,
compounds
bonded
The conerson of alkanes to
Stretching
by
Two
cycloalkanes or cycloalkanes to arenes.
Photodissociation
bond
more
steam.
atoms
arrangement
of UV
a
Replenshes the wood resource and
2
oxdes
of
mmscble
replace depleted forests or woodland.
Stereoisomerism
Photochemical
an
Plantng of young trees to
mxture
an
Dstllaton
agents.
njecton
of
by
another.
a
detecton.
T
the functonal
group
s
dfferent
but
Retention value,
R
In
chromatography
f
the
molecular formula
s
Potentiometric titration
nolng
measurement
electrode
Precise
measurements
Primary
of
changes
n
Precse
close
to
each
to
a
attached
to
only
the
dstance
Reuse
n alue.
(referrng
dstance
from
base
are ery
attached
184
the
Ttraton
moed
base
of
lne,
the
by
a
compound
dded
by
solent front from
the
use
once for
somethng
the
same
or
a
more
than
dfferent
to
alcohols
carbon
one
and
or Cl
atom,
other
Reverse osmosis
s
whch
carbon
desalnaton
s
through
from
a
a
n
Method
whch
regon
of
concentraton.
hgh
to
reacton
combne
n
whch
to form
two
a
molecule.
(referrng
to
alcohols
halogenoalkanes) The
attached
to
a
carbon
attached
to
three
OH
or
atom
other
and
Cl
s
whch
s
carbon
atoms.
of
water
sem-permeable
A
radcals
Tertiary
lne.
To
Termination
free
the
purpose.
halogenoalkanes) The OH
atom.
same.
potentals.
(precision)
other
the
s forced
membrane
low
salt
Tetravalency
The
quantum
shell. These form four
other
outer
has four alence
n
wth
ts
atom
electrons
atoms.
prncpal
bonds
Glossary
Thermometric
titrations
Ttratons
U
nolng
measurement
of
changes
Ultraviolet
temperature.
Thin-layer
chromatography
chromatography
phase
s
phase
a
Tollens’
lqud
thn
n
used
of
the
the
the
form
of
moble
statonary
sold.
Ammonacal
for
dstngush
whch
and
layer
reagent
ntrate
to
a
A
sler
aldehydes
(UV)
waelength
Unsaturated
Radaton
between
Compounds contanng
test
wth
dfferent
an
The
alcohol
ester
and
a
form
of
an
atmosphere
them saturated.
passng
Turbidity
matter
The
n
a
through
a
cloudness
lqud.
(%)
and
Wavenumber
Vacuum distillation
reduced
speed
Dstllaton
of
In
s
of
n
whch
the
the
Earth
and
constantly
condensng.
IR
spectroscopy,
of braton
dded
the
by
the
lght.
under
pressure.
Vapour pressure
of
soluton.
of
eaporatng
surface
of
created.
process
n
the
preenton
Z
a
dfferent
percentage
The
the
The
beng
carbon–carbon bonds). Hydrogen can
The pressure exerted by
apour molecules n a closed system.
The
cycle
frequency
alcohol.
Transmission
Water
materal
on
from
reacton
to
reduction
waste
water
V
Transesterication
lght
Waste
4–400 nm.
double or trple bonds (usually
ketones.
ester
of
about
be added to these compounds to make
sler
mrror
W
n
suspended
Visible
(vis)
about
Radaton
waelength
400–700 nm.
Visualising
agent
to
speces
charge
An
wth
n
electrcally
a
two
poste
dfferent
neutral
and
negate
parts
of
the
on.
Chemcal
chromatography
spots
of
Zwitterion
make
used
n
colourless
coloured.
185
Index
Key
n
terms
the
are
n
bold
and
are
also
lsted
barum
base
glossary.
chlorde
peaks
bases
46,
bauxte
absorbance
50–7
,
see also
A
74,
accuracy
acd
70,
haldes
164,
98
conductty
41,
benzene
3,
46,
137
,
37
,
manganate
(vii)
conjugative
constant
effect
boiling
50–1
mixtures
5,
15,
42–5
Contact
Process
150,
118
151
38,
83,
39
corroson
152
coupling
resstance
reactions
132
47
23
97
,
144
ponts
115,
acds
27
,
34–5,
41,
120,
125
cracking
18,
crude
134–5
ol
136
2–3,
11,
40
cryolite
131
50–1
branched-chan
74,
117–18,
125
bonds
alkanes
8–9,
14–15
cyandes
32–3,
97
,
158,
159
76–85
brine
haldes
92–3
168–9
50–7
,
carboxylc
ttratons
law
54
bolng
acyl
84
132
141
potassum
22,
60–1
72–3
blood
acds
35,
5
conductimetric titrations
133
bending
bleach
rain
condensed formulae
165
biodiesel
acid
125
62–3
reactions
92–3
150–1,
acdcaton
acded
76–85,
titrations
ore
polymers
condensation
Beer–Lambert’s
absorpton
condensaton
87
104
46,
146–7
54
bromne
21,
22,
42–6,
148
D
addton
polymers
addition
62,
reactions
adsorpton
159,
adsorption
63
20,
bromoalkane
32–3,
58–9
burettes
hydrolyss
29
data
77
177
analyss/measurement
dehydration
chromatography
108
delocalised
reactions
electrons
70–5
27
3
C
aeraton
of
air lters
ar
water
ethanol
alkals
calcum
101,
16,
141,
26–7
,
52,
aldehydes
alkalne
167–8,
35,
118–19,
30,
31,
hydrolyss
39,
170–3
41,
124
alkanes
carbonates
37
alkenes
8–9,
14,
2–3,
15,
20–3,
alternative fuels
128–33,
alumnum
oxde
amides
54,
amines
54–5
55,
acids
ammona
tablets
CFCs
asbestos
salts
170
doxn
30–3,
34–5,
40
41,
151,
172
DO
47
152,
168–9
149
oxygen
dryng
146
of
156–7
124–5,
coefcients
bonds
ductlty
5
(DO)
116–21,
(dssoled
double
2
131,
150,
dssoled
136
147
47
displayed formulae
50–1
169
173
146,
emssons
distribution
139,
ran
159
39
dstllaton
cracking
oxygen)
156–7
40
samples
86–7
132
160–1,
165
E
chiral
156–8
isomerism
centres
chlor-alkal
44
compounds
3,
chlordes
42–9
chlorne
15
10
electrcal
13
ndustry
148,
conductty
electrodialysis
149
electrolyss
88–9
hydrolyss
131,
133,
acds
electromagnetc
29
electrons
51
132
157
electromagnetic
148
chloroalkane
149
146–7
radiation
spectra
90
19
82
chlorofluorocarbons
atmospherc
carbon
atmospherc
ntrogen
uptake
oxdes
ozone
mass
electrophiles
20,
42,
empirical formulae
108–13
43
4,
isomerism
12,
22,
enantomers
23
6
12–13
products
energy
83
91,
128
103
clmate
Aogadro’s
law
azeotropic
mixtures
change
engnes
165
167
7
coagulaton
enronment
159
156–79
118
coefcients of distribution
azo dyes
165
160–1
cleanng
atomc
160–1,
167
cis-trans
atmospherc
(CFCs)
162–3
chromatography
alumnum
122–3
128–9,
133
47
colormetry
column
ammona
74–5
chromatography
109,
110,
112
141
chlor-alkal
ndustry
149
B
combuston
back titrations
bactera
100
18,
137
,
communcatons
complexng
173
regions
186
78–9
167
bag lters
band
143,
108
177
162,
networks
reagents
components
compostng
150,
94
170–1,
128
176
ethanol
144–5
petroleum
errors
n
137
measurement
esterication
esters
36–7
,
35,
41,
72
39
60,
157
122–3
67
chloroethanoc
asprn
diazonium
desel
(chlorouorocarbons)
chain
82–3
compounds
cathodes
cellulose
166
enronments
42–3,
140–1
cells
doxdes
162–5,
27
,
daphragm
diazotisation
109
136,
catenation
64–5
138–9,
2–17
167
gases
catalytic
56–7
,
78
162–3
acids
engnes
catalysts
146
aromatic
car
41,
compounds
carboxylic
acd
157
,
desulphursaton
hydrocarbons
cycle
of
desalination
66–7
35,
166
132
deposton
20
doxde
carbonyl
carrer
oxdaton
arenes
62
131
anodes
aquatc
58–9,
61
54–5,
131,
carbon
carbon
175
ammonum
antacd
62
172
alumnum
amino
18–19,
halogenoalkanes
densty
75
75
compounds
see also
bases
4,
curves
carbohydrates
40–1
78
instruments
calibration
carbon
see also
carbonate
calibrated
carbocation
142–5
33,
46
see also
aryl
denitrication
173
polluton
alcohols
159
62–3
90
Index
ethane
62
hydrated
ethanoate
ethanoc
ethanol
ethene
ons
acd
52,
2,
ethoxde
52,
53
53
3,
58,
142–5
59
52
eutrophication
88
141
methylbenzene
miscible
18–25,
mobile
170–1
22–3
hydrogen
bromde
hydrogen
chlorde
hydrogen
cyande
35,
haldes
peroxde
content
molecular
41
molecular
45
hydrogen
114
chromatography
moles
ion
108
87
6–7
104
103
88
monomers
20–1
4,
peaks
mass
phases
analyss
molecular formulae
21
32–3
hydrogen
44
liquids
mosture
hydrogen
hydrogencarbonates
F
fats
87
,
145
hydrocarbons
118–19,
ons
salts
hydraton
58,
62–3
83
38
hydrolysis
fatty
acds
22,
23,
hydroxde
Fehling’s
solution
fermentation
29,
36–7
N
38
31,
142,
groups
46,
52
ntrates
41
158,
nitration
145
159
43,
44,
45
I
fertlsers
lters
173
ltraton
ideal
86,
ngerprint
xaton
ash
of
159,
ntrogen
dstllaton
ue-gas
uorne
173
regions
occulaton
food
ntrobenzene
140–1
nitrogen
114
liquids
100
ncomplete
combuston
167
ndcators
157
inductive
159
desulphursaton
173
80,
124,
infrared
(IR)
114,
18,
137
,
170
152
nuclear
51
128–9,
130–7
,
spectroscopy
odne
fractional distillation
116,
117
,
124,
157
reactions
98–101,
134–7
96,
hydrolyss
ndustry
radicals
19,
124
IR
160–1,
169
reactions
157
,
38,
137
27
isomerism
desalnaton
157
spectroscopy
98–101
157
97
isomers
90–1
IUPAC
(Internatonal Unon
of
Pure
131,
cells
172
Appled Chemstry)
39,
143,
162,
group
168–9
168
156–7
160–1,
165
170–1
ozone depletion
functional
166,
167
,
8
ozone
fuels
159,
165,
and
oxygen
fuel
26–7
,
10–15
oxdes
frequencies
12–13
133
oxdaton
freeze
42
159
(nfrared)
ron
28–9,
61
29
osmoss
free
32–3
19
ore
fragrance
29,
substitution
O
odoalkane
ons
167–9
115
177
28,
149
iodoform
104
waste
nucleophilic
optical
fragmentation
167
165,
mxtures
nucleophiles
138–55
ols
fractions
166–7
oxdes
nylon-6,6
initiation
4–7
ntrogen
non-deal
100–1
preseraton
cycle
45
nitrogen xation
120
84–5
effect
ndustry
148
formulae
solutions
immiscible
44,
isomerism
161
10–11
K
ozone
functional
see also
groups
4,
hydroxide
9–11,
17
,
26–41,
layer
149,
161
52
ketones
groups
30,
31,
33,
40–1
P
L
G
gas–liquid
111,
chromatography
109,
174–5,
global
landlls
lead
113
geometrical
glass
(GLC)
isomerism
12,
22,
23
137
,
lght
159,
see
lquds
164–5
175,
paper
chromatography
176
methods
114–15
partial vapour
pressure
110–11,
114
partition
chromatography
partition
coefcients
partitioning
glucose
109,
112–13
167
99,
paper
171
spectroscopic
lghtnng
176
warming
177
108
122–3
108
97
pectn
gravimetric
analysis
76,
86–9
67
M
peptdes
greenhouse
effect
greenhouse
gases
64
164
M
+
1
peaks
105
pestcdes
158
165
magnetsm
132
malleablty
PET
132
(poly(ethene
petroleum
125,
terephthalate))
134–7
,
175
158
H
mass
Haber
Process
138–9,
halogenoalkanes
halogens
HDPE
heatng
heay
18,
(hgh
of
samples
102–5,
175
densty
resoluton UV-sble
poly(ethene)
(HDPE)
175
spectroscopy
series
homolytic ssion
hybridisation
16–17
carboxylc
3
144,
160
128–33,
acds
chlor-alkal
sold
35
176
polluton
methane
158
165
methylamne
175
ndustry
137
waste
water
19
141,
2
4–5,
phenylamne
63
158,
phosphorus
(iii)
phosphorus
(v)
chlorde
smog
(π)
bonds
p
(π)
orbtals
plant
35
35
141,
161,
170–1
160
162
76–7
p
2,
58,
polluton
3
50
dersty
plastcs
54–5
159
chlorde
photodissociation
ppettes
53
55
photosynthess
149
53
52,
photochemical
petroleum
94–5
47
,
ons
phosphates
149
alumnum
hgh
46,
phenoxde
phenylethene
metals
19
hgh
health
102–5
71
mesomerism
158
homologous
phenols
102
172
mean values
mercury
87
132
ratios
spectrometry
mass transit
poly(ethene))
158
heterolytic ssion
human
mass
40
148–9
densty
metals
herbcdes
28–9,
87
,
mass/charge
166
141
137
,
101,
175,
141,
176
158–9,
167–8,
170–3
187
Index
polyamides
61
resources
174–5
T
polyesters
60,
poly(ethene)
poly(ethene
62–3
respraton
58
162
retention time
terephthalate)
(PET)
175
111
retention value
Teon
)
(R
110–11,
112
59
temperature
72,
139,
151
f
polymerisation
polymers
58–69,
polypeptdes
reusable
58–61
149,
poly(propene)
R
poly(styrene)
groups
rng
63
rum
66–7
termination
157
5,
15,
46
benzene
ndustry
tertiary
halogenoalkanes
(PVC)
(PTFE)
thermal
59,
149
110,
10,
47
,
87
,
88,
157
,
dchromate
(vi)
potassum
manganate
(vii)
41,
23,
81
31,
tn
saturated
23
scrubbers
173
41,
chlorde
ttratons
secondary
samples
analysis
alcohols
26,
109,
35
74,
76–85
reagent
30–1,
40
27
85
transesterication
secondary
halogenoalkanes
secondary
pollutants
39
28
86
transton
element
ons
96
170
70
turbidity
sedmentaton
(TLC)
45
Tollen’s
potentiometric titrations
85
chromatography
38
80–1
prexes
132
112–13
thonyl
31,
29
159
11
potassum
28,
2
conductty
thin-layer
S
saponication
precision of
27
62
tetravalency
124
59
salts
isomerism
of
60,
26,
19
alcohols
thermometric titrations
chlorde
precptatng
reactions
tertiary
Terylene
175
poly(tetrauoroethene)
positional
174
16
compounds
see also
62
polysaccharides
polynyl
reverse osmosis
175
64
poly(phenylethene)
resources
159
159
8
separaton
preseraton
of food
technques
108–27
,
135
152
U
sequestering
pressure
114,
119,
139,
sgma
primary
alcohols
primary
halogenoalkanes
primary
pollutants
(σ)
standards
reactions
unknowns
spectroscopy
calculatons
94–7
78–9
dstllaton
plants
116
unsaturated
128–9
urea
22–3,
40
97
141,
161,
170–1
UV
light
94–7
19
38
sodum
46
sodum
carbonate
V
64–5
(poly(tetrauoroethene))
(polynyl
chlorde)
59,
controls
41
59
(i)
vacuum distillation
sodum
chlorate
sodum
chlorde
83
sodum
hydrogencarbonate
apour
146
sodum
hydroxde
sodum
thosulphate
34,
147
,
41
149
ttratons
87
,
141,
124
pressure
negar
82
(vis)
visualising
solublty
125
solutons
73–5,
165
114
light
spectroscopy
94–5,
96
169
91
133
solvent
114,
vapour
visible
81
89
sol
quarryng
119,
149
Q
quanta
40
62
proteins
qualty
ultraviolet
30–1,
74
soap
PVC
2
28–9
smog
PTFE
test
170
smeltng
propene
bonds
mrror
smple
propagation
172–3
26
sler
primary
agents
151
tamn C
114
extraction
trcaton
122–5
solvent front
110
spectroscopc
methods
agents
110
83
177
olatle
organc
olume
72
compounds
(VOCs)
R
radaton
96–101
see also
ran
137
,
standard deviation
ultraviolet
spectroscopy
168–9
Raoult’s
law
standard
starch
114–15
solutons
71,
90–107
olumetrc asks
76
66–7
stationary
W
chromatography
phases
washng
raw
materals
128,
138
mechanisms
19
steam distillation
120–1,
174–5
steel
80–1
stems
pressure
dstllaton
119
reduction
57
,
88,
reactons
33
stereoisomerism
stretching
waste
174
12–13
strong
acd–strong
base
ttratons
158–9
132
structural formulae
cycle
163
structural
5
isomerism
90–1
10
wavenumbers
reforming
relative
relate
136–7
substitution
abundance
atomc
102
mass
103
42,
reactions
18,
19,
resdue
units
resonance
resonance
188
58
separatons
135
3
hybrids
weak
acd–strong
weak
base–strong
base
ttratons
84
acd
ttratons
84
46
sufxes
8
sulphur
dchlorde
sulphur
doxde
sulphurc
3
98–101
28–9,
weghng
repeating
157
156
waelengths
reforestation
156,
84
water
reectty
165
87
98
purcaton
reduction of
174
128,
crystallsaton
polluton
reducton
97
,
8
of
reduced
173
176–7
175
water
redox titrations
149,
124
waste
recycling
86,
108
waste
reaction
73
74–5
acd
suspended
oxde
150,
22,
35
152
27
,
partcles
72
Z
150–3
158
zwitterions
56
171
Chemistry
for
Unit
2
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