Environmental Chemistry
It often matters how much given atoms
combine, in what arrangement, with what
others, what impulse they receive, and what
impart. The same ones make up earth, sky,
sea, and streams; the same the sun, the
animals, grains and trees, but mingling and
moving in every different ways.
- Lucretius (95-52 B.C.) in The Nature of
Things
I. Physical Chemistry
Why is Physical Chemistry important in
the study of Environmental
Engineering?
• Applied physical chemistry
procedures is used to solve common
environmental engineering problems
1. Stoichiometry
• It deals with numerical relationships
between reactants and products in
chemical reactions.
• Stoichiometric analysis can be used
to determine the product yield for a
given amount of reactant converted.
Example of Stochiometric Analysis
• Neutralization of hydrochloric acid
with lime
2HCl + Ca(OH)2  CaCl2 + 2H2O
• Oxidation of acetic acid to carbon
dioxide and water.
CH3COOH + 2O2  2CO2 + 2H2O
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Example of Stochiometric Analysis
• Combustion of Methane
CH4 + 2O2  CO2 + 2H2O
• Oxidation of glucose
C6H12O6 + 6O2 6CO2 + 6H2O
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Sample Problem 1
Freight train cars usually carry a maximum
net weight of about 100,000 lbs. I f a train
is carrying three cars of concentrated
sulfuric acid (assume that it is 96% acid),
how much lime [Ca(OH)2] would be
required to neutralize the acid if it is spilled
in a derailment or wreck? The
neutralization reaction is
H2SO4 + Ca(OH)2 CaCl2 + 2H2O
Sample Problem 2
What mass of carbon dioxide would
be produced if 100 g of butane
(C4H10) is completely oxidized to
carbon dioxide and water?
Theoretical Oxygen Demand
(ThOD)
• It is an environmental engineering
application of stoichiometry.
• The estimation of the amount of oxygen a
known organic chemical will consume as it
is converted to carbon dioxide and water.
• It is simply the amount of oxygen required
to convert the material to carbon dioxide
and water.
Engr. Yvonne Ligaya 9F. Musico
Sample Problem 3
Consider a 1.67 x 10-3 M glucose
solution (C6H12O6) that is completely
oxidized to CO2 and H2O. Find the
amount of oxygen required in mg/L to
complete the reaction.
Sample Problem 4
Worldwide combustion of methane, CH4
(natural) gas, provides about 10.9 x 1016
kJ of energy per year. If methane has an
energy content of 39 x 103 kJ/m3 (at STP),
what mass of CO2 is emitted into the
atmosphere each year? Also express that
emission rate as metric ton of carbon (not
CO2) per year. A metric ton, which is
1,000 kg, is usually written as tonne to
distinguish it from the 2,000-lb American,
or short, ton.
2. Equilibrium Chemistry
•
It can be used to analyze a variety
of different aqueous reactions of
interest to the environmental
engineer – or the environmental
engineering student.
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Equilibrium Chemistry
Example:
1. Determining the amount of base to add to an
acid spill
2. The amount of acid to neutralize a basic
process wastewater
3. The solubility of metal in a chemical waste
stream
4. Estimating the removal of phosphorus in a
wastewater treated with lime
5. Solubility of mercury complexed in seawater.
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Chemical Equilibria
• The state in reversible reaction in
which the rates of the forward and
reverse reactions are equal.
• A state achieved when the rates of
the forward and reverse reactions are
equal and the concentrations of the
reactants and products remain
constant.
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EQUILIBRIUM CONSTANT, Kc
aA + Bb  cC + Cd
Coefficients in the chemical equation become exponents
in the equilibrium constant expression.
c
d
[C ] [ D]
Kc 
[ A]a [ B]b
Include only substances in the gas or aqueous phase.
Solid’s and liquid’s concentrations do not change
during a chemical reaction.
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EQUILIBRIUM CONSTANT, Kc
Where:
[ ]
c, d, a, b
= concentration M = mol/L
= are the coefficient in the
balanced equation
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Using Equilibrium Constant
• The reaction quotient (Qc) is obtained by
substituting initial concentrations into the
equilibrium constant. Predicts reaction direction.
Qc > Kc System proceeds to form reactants.
Qc = Kc System is at equilibrium.
Qc < Kc System proceeds to form products.
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What Q tells us
• If Q<K
: Not enough products
: Shift to right
• If Q>K
: Too many products
: Shift to left
• If Q=K system is at equilibrium
Acid ionization constant of weak monoprotic acid
HA + H2O  H3O+ + Aor
HA + H2O  H+ + A

[ H ][ A ]
Ka 
[ HA]
Base ionization constant of weak base
For the aqueous solution of ammonia,
NH3 + H2O ↔
NH4+

+

[ NH 4 ][OH ]
Kb 
[ NH 3 ]
OH-
Sample Problem 4
Worldwide combustion of methane, CH4 (natural)
gas, provides about 10.9 x 1016 kJ of energy per
year. If methane has an energy content of 39 x
103 kJ/m3 (at STP), what mass of CO2 is emitted
into the atmosphere each year? Also express that
emission rate as metric ton of carbon (not CO2)
per year. A metric ton, which is 1,000 kg, is
usually written as tonne to distinguish it from the
2,000-lb American, or short, ton.
Acid and Base
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table_03_05
Sample Problem 5
(Drinking Water Disinfection Using
Chlorine)
Chlorine is the active ingredient in most household bleach and is
one of the most commonly used and inexpensive chemical
disinfectants for water. The chlorine in the hypochlorous acid
form, HOCl, and hypochlorous acid is a much better disinfectant
than hypochlorine, OCl-, its conjugate base. If bleach is used to
disinfect; below what pH should water be maintained so that at
least 95 percent of the chlorine added is in hypochlorous acid
form?
HOCl  OCl- + H+
pKa = 7.60
Sample Problem 6
What percentage of total ammonia (i.e.,
NH3 + NH4+) is present as NH3 at a pH
of 7? The pKa for NH4+ is 9.3
The Carbonate System
• The most important
acid-base system in
natural waters
because it largely
controls pH
• Carbon dioxide and
carbonates are
crucial in water
chemistry.
Engr. Yvonne Ligaya F. Musico
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table_03_06
Solubility Product Constant
The solubility product constant, Ksp, is a
measure of the solubility of such
slightly soluble compounds.
Solubility Product Constant
For general case, consider the slightly soluble
ionic compound,
AmBn(s)
mAn+ +
nBm-
And the Ksp expression is
n m
m n
K sp  [ A ] [ B ]
Solubility Product Constant
Example
For the reaction below, what is the solubility
product expression?
CaCO3(s)
Ca2+ +
The Ksp expression is
Ksp = [Ca2+][CO32-]
CO32-
Sample Problem 7
• What pH is required to reduce a high
concentration of dissolved Mg2+ to 43
mg/L? Ksp for the following reaction is
10-11.16.
Mg(OH)2(s)  Mg2+ + 2OH-
Sample Problem 8
• Find the equilibrium concentration of
fluoride ions in pure water caused by
the dissociation of CaF2. Express the
answer both in units of mol/L and
mg/L.
Solubility of Gases in Water
Henry’s Law
Cg = KHPg
Where
Cg = concentration of A [mol/L] or [mg/L]
KH = Henry’s Law constant [mol/L.atm] or
[mg/L.atm]
PA = partial pressure of A [atm]
Sample Problem 9
By volume, the concentration of oxygen
in air is about 21 percent. Find the
equilibrium concentration of O2 in water
(in mol/L and mg/L) at 25oC and 1 atm.
The Henry’s Law constant of oxygen in
water at 25oC is is 0.0012630
mol/L.atm.
Air Stripping
• It is a common method of removing
dissolved gases from water and
wastewater. Gases commonly
removed include ammonia, carbon
dioxide, and hydrogen sulfide.
Sample Problem 10
Nitrogen in a wastewater treatment plant is in the form
of ammonia and ammonium ion and has a total
concentration of 7.1 x 10-4 M. The Henry’s constant (at
25oC) is 57 mol/L.atm.
(a) Find the fraction of nitrogen that is in the ammonia
form (and hence stippable) as function of pH.
(b) If the wastewater pH is raised to 10 and
atmospheric ammonia concentration is 5.0 x 10-10
atm, what would be the equilibrium concentration
of total nitrogen in th wastewater after air stripping?
Sample Problem 11
An air-stripping tower is used to remove
dissolved carbon dioxide from a
groundwater supply. If the tower lowers the
level to twice the equilibrium concentration,
what amount of dissolve gas will remain in
the water after treatment? The partial
pressure of carbon dioxide in the
atmosphere is 1 x 10-3.5 atm. The Henry’s
Law constant is 0.033363 at 25oC.
Adsorption
• It is a surface phenomenon in which a
solute (soluble material) concentrates
or collects at a surface.
• This contrasts with ABSORPTION,
which a substance penetrates the
material.
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Common Adsorbents
• Silica gel
• Zeolites
• Activated carbon
Mathematical Models to Predict the Mass of
Solute Removed per Mass of Adsorbent
FREUNDLICH ISOTHERM
qe = _x_
m
Where:
qe =
x
m
K
n
=
=
=
=
=
KCe1/n
mass of solute adsorbed per mass of
adsorbent used [mg adsorbed/mg carbon]
mass of solute adsorbed [mg or mol]
mass of adsorbent [mg]
experimental constant
experimental constant
Mathematical Models to Predict the Mass of
Solute Removed per Mass of Adsorbent
LINEARIZED FREUNDLICH EQUATION
log (x/m) = log K + (1/n) log Ce
If log (x/m) is plotted versus log Ce, the
data should fit a straight line.
Mathematical Models to Predict the Mass of
Solute Removed per Mass of Adsorbent
LANGMUIR ISOTHERM
qe = _x_
m
Where:
qe
=
x
m
K
Q0
=
=
=
=
=
_KQ0Ce__
1 + KCe
mass of solute adsorbed per mass of
adsorbent used [mg adsorbed/mg carbon]
mass of solute adsorbed [mg or mol]
mass of adsorbent [mg]
experimental constant [L/mg]
constant representing the mass of solute
adsorbed per mass of adsorbent at saturation
Mathematical Models to Predict the Mass of
Solute Removed per Mass of Adsorbent
LINEARIZED LANGMUIR ISOTHERM
_1__
x/m
= _1_ +
Q0
_1_
KQ0
_1_
Ce
If (1/qe) is plotted versus (1/Ce), the data fit a straight line.
3. Chemical Kinetics
• The study of the rates and
mechanisms of chemical reaction.
• Rate of reaction - the amount of
chemical change that takes place in a
given interval of time.
The Rate of Chemical Reaction
• The rate at which reactants are
consumed or products are produced in a
chemical reaction
• Will a reaction occur?
Collision Theory
for a reaction to occur:
-reactant particles must collide
-collision must have a certain minimum
amount of energy: Activation Energy
-reactants may require a specific
orientation
Potential Energy Diagrams
E
Activation Energy,
Ea
Avg. Energy of Products,
PEP
E energy
absorbed during the
reaction
Avg. Energy of Reactants, PER
reaction progress
Endothermic Reaction
46
Rate Law
For General Reaction:
aA + bB  cC + dD
The rate law generally has a form
Rate = k[reactant 1]m[reactant 2]n
For the reaction above,
Rate = k[A]a[B]b
where k in the rate law is called the rate constant
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Order of Reaction
• The sum of all the exponents of the
concentration terms in the rate equation
Sample Problem 12
How long will it take the carbon monoxide
(CO) concentration in room to decrease by
99 percent after the source of carbon
monoxide is removed and the windows are
opened? Assume the first order rate constant
for removal (due to dilution by incoming
clean air) is 1.2/hr. No chemical reaction
occurring.
Half-Life (t½)
• It is defined as the time required for
the concentration of a chemical to
decrease by one-half (for example,
[C] = 0.5[C]0).
Sample Problem 13
• Subsurface half-lives for benzene,
TCE, and toluene are listed as 69,
231, and 12 days, respectively. What
are the first-order rate constant for all
three chemicals.
Sample Problem 14
• After a Chernobyl nuclear accident, the concentration
of 137Cs in milk was proportional to the concentration
of 137Cs in the grass that cows consumed. The
concentration in the grass was, in turn, proportional to
the concentration in the soil. Assume that the only
reaction by which 137Cs was lost by soil was through
radioactive decay and the half-life for this isotope is 30
years. Calculate the concentration in milk shortly after
the accident was 12,000 bequerels (Bq) per liter.
(Note: A bequerel is a measure of radioactivity; 1
bequerel equals 1 radioactive disintegration per
second.)
Effect of Temperature on Rate
Constants
Arrhenius equation
k = Ae –(Ea/RT)
Where:
A
Ea
R
T
– preexponential factor (same as k)
– activation energy (kcal/mole)
- gas constant
- temperature (K)
Sample Problem 15
The rate constant for carbonaceous
biochemical oxygen demand (CBOD)
at 20oC is 0.1/day. What is the rate
constant at 30oC? Assume Ea = 1.072.
II. Organic Chemistry
• It is defined as the
study of
hydrocarbons
(compounds of
hydrogen and
carbon) and their
derivatives.
Organic Compounds
Why Study Organic Chemistry in
Environmental Engineering?
• 10 million Organic Compounds
• 1.7 million Inorganic Compounds
• Animal and plant matter, Foods,
Pharmaceuticals, Cosmetics,
Fertilizers, Plastics, Petrochemicals,
Clothing
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F. Musico
Production of Organic Chemicals
The Top Five Organic Chemicals Produced in the
United States in 1990
CHEMICAL
PRODUCTION, 1000 MT
Ethylene
17,001
Propylene
10,034
Urea
7,171
Ethylene dichloride
6,033
Benzene
5,380
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Properties of Organic Chemicals
1.
2.
3.
4.
5.
6.
7.
They are combustible
Their melting and boiling points are lower than
those inorganic compounds.
Their solubility is limited
They undergo molecular reactions as opposed to
ionic reactions.
They can have very high molecular weights
They are isomers (different compounds with the
same chemical formula but different structural
formula).
They form a substrate for microorganism.
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Carbon
Why is it the element of life on earth?
Has Four Bonding Electrons
Unique Strong Covalent Bonds
Strong Single, Double and Triple Bonds
Average Bond Energies (KJ mol-1)
C-C
607
Si-Si
230
C-H
416
Si-H
323
C-N
754
Si-N
470
C-O
336
Si-O
368
O-Si-O = Sand and Rocks
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– Carbon: normally forms four covalent bonds and has no
unshared pairs of electrons.
C
– Hydrogen: forms one covalent bond and no unshared
pairs of electrons.
H
– Nitrogen: normally forms three covalent bonds and has
one unshared pair of electrons.
N
..
– Oxygen: normally forms two covalent bonds and has two
unshared pairs of electrons.
..
.O. =
– Halogen: normally forms one covalent bond and has three
unshared pairs of electrons.
Engr. Yvonne Ligaya F. Musico
..
..Cl
..
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Hydrocarbons
• Containing only carbon and hydrogen
Saturated hydrocarbons
Unsaturated hydrocarbons
Alkanes
H
Alkenes, Alkynes
& Aromatics
H
C-C
C=C
H
C
C
C
C
C
H
CC C
H
H
A Kek ulé structure
A Keku lé structu re
show ing all atoms as a line-angle formul
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Hydrocarbons
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Alkanes
• Hydrocarbons which contain only
single bonds are called alkanes.
• They are called saturated
hydrocarbons because there is a
hydrogen in every possible location.
• This gives them a general formula
CnH2n+2.
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Alkanes
H
H C H
H
methane
CH3
H H
H C C H
H H
ethane
CH3CH3
CnH2n+2
H H H H
H C C C C H
H H H H
H H H H H
H C C C C C H
H H H H H
propane
butane
pentane
CH3CH2CH3
CH3CH2CH2CH3
H H H
H C C C H
H H H
Engr. Yvonne Ligaya F. Musico
CH3CH2CH2CH2CH3
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Naming Alkanes
Prefix for number of carbons listed below and
suffix – ane are used.
Number of Carbons
As Prefix
Name
1
Meth -
Methane
2
Eth-
Ethane
3
Prop-
Propane
4
But-
Butane
5
Pent-
Pentane
6
Hex-
Hexane
7
Hept-
Heptane
8
Oct-
Octane
9
Non-
Nonane
10
Dec-
Decane
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Alkyl Groups
• If a hydrogen is removed from an alkane, it
can be used as a substituent and is called
an alkyl group.
• Alkyl groups are named by dropping the ane suffix of the alkanes and adding the
suffix -yl. Methane becomes a methyl
group, ethane an ethyl group, etc.
• Alkane Derivatives - Can be formed by
substituting an alkyl group for one of the
hydrogens.
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Naming Substituents
In the IUPAC system:
• Removing a H from an
alkane is called alkyl
group.
-ane
-yl
• Halogen atoms are
named as halo.
-ine
-O
-OH
-NO2
Hydroxyl
Nitro
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Cycloalkanes
• Cyclic alkanes
• Cycloalkanes have higher boiling point/melting point than
straight chain alkanes with the same number of carbon
atoms
Cyclobutane
Cyclopentane
Engr. Yvonne Ligaya F. Musico
=
Cyclohexane
68
Properties and Uses of Alkanes
• Gasoline is a mixture of alkanes from pentane up to about
decane.
• Gases with 1-4 carbon atoms. (methane, propane, butane
• Liquids with 5-17 carbon atoms. (kerosene, diesel, and jet
fuels)
• Alkanes with higher values of n are found in diesel fuel, fuel
oil, petroleum jelly, paraffin wax, motor oils, and for the
highest values of n, asphalt.
• Alkane derivatives are used in hundreds of products such as
plastics, paints, drugs, cosmetics, detergents, insecticides,
etc., so the fossil fuel resource from which we obtain the
alkanes is much too valuable to burn it all as a motor fuel.
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Alkenes and Alkynes
Saturated compounds (alkanes):
Have the maximum number of hydrogen
atoms attached to each carbon atom.
Unsaturated compounds:
Have fewer hydrogen atoms attached to
the carbon chain than alkanes.
• Containing double bond are alkenes.
CnH2n
• Containing triple bonds are alkynes.
CnH2n-2
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Naming Alkenes & Alkynes
Using the IUPAC alkane names:
Alkene names change the end to -ene.
Alkyne names change the end to -yne
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Ethyne
• The simplest of the alkynes series, it
is commonly called acetyline.
• It is often used as a fuel for welding
torches sinces it produces a large
amount of heat upon combustion.
• Oxyacetylene welding uses
compressed acetylene and
compressed oxygen for mixing in the
torch flame.
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Aromatic Hydrocarbons
• Have ring structure with multiple bonds.
• Benzene (C6H6) is the simplest
aromatic.
Benzene
C6H6
H
H
C
C
H
C
C
H
C
C
Engr. Yvonne Ligaya F. Musico
H
H
H
H
C
C
73
H
C
C
H
C
C
H
H
Aromatic Hydrocarbons
• Many common spices contain aromatic
compounds as their active ingredients.
Examples:
–
–
–
–
Cumin contains cumene
Black pepper contains piperine
Clove contains eugenol
Cinnamon contains cinnamaldehyde
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Aromatic Compounds
Arene: A compound containing one or more benzene rings.
H
H
C
H
Aromatic compounds
are
C
C named:
•
•
C
C
Naphthalene
H
C
H
With benzene as the parent chain.
H
Name of substituent
comes in front of the “benzene”.
A Kek ulé structure
A Keku lé structu re
show ing all atoms as a line-angle formula
CH2 CH3
CH CH
CH-CH CH=CHC
2
CH
CHCl
CH=CHCH
CH
3 2 CH3
3
2 3 2 23 3
Eth ylb enzene
methylbenzene
Eth ylbeenzene
Toluen
chlorobenzene
Toluen
Eth ylb
e enzene Styrene
Tolu
Styrene
ethylbenzene
Biphynels
• Aromatic compounds with two phenyl or benzene
rings attached by a single carbon-carbon bond.
• Polychlorinated biphenyls (PCBs) were used
extensively in industry until 1972.
• Because of their widespread use and release,
they will remain in the environment for years to
come because they degrade slowly.
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F. Musico
Hydrocarbon Fuels
• Hydrocarbon fuels comprise some
88% of the world’s energy supplies at
present.
• The three major fuels are petroleum
or crude oil, coal and natural gas.
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Hydrocarbon Fuels
• Petroleum is a complex mixture of
organic carbons, primarily alkanes. It
also contains small amount of
nitrogen, oxygen and sulfur
compounds.
• Coal is a complex mixture. A large
percentage of the coal is carbon and
contained in linked aromatic rings.
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Hydrocarbon Fuels
• Hydrocarbon fuels comprise some
88% of the world’s energy supplies at
present.
• The three major fuels are petroleum
or crude oil, coal and natural gas.
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Hydrocarbon Fuels
• Petroleum is a complex mixture of
organic carbons, primarily alkanes. It
also contains small amount of
nitrogen, oxygen and sulfur
compounds.
• Coal is a complex mixture. A large
percentage of the coal is carbon and
contained in linked aromatic rings.
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Hydrocarbon Fuels
• Hydrocarbon fuels comprise some 88% of the
world’s energy supplies at present.
• The three major fuels are petroleum or crude oil,
coal and natural gas.
• Petroleum is a complex mixture of organic
carbons, primarily alkanes. It also contains small
amount of nitrogen, oxygen and sulfur
compounds.
• Coal is a complex mixture. A large percentage of
the coal is carbon and contained in linked
aromatic rings
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Alcohols and Ethers
• Alcohols and Ethers can be regarded
as derivatives of water in which one
or two of the H atoms has been
replaced by an alkyl group.
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82
Alcohols
• Alcohols are found to have much higher boiling
point than those of alkanes or haloalkanes of
comparable size, e.g. Methanol (65 oC),
Chloromethane and Methane are gases ; Ethanol
(78.5 oC), Chloroethane (12 oC) and Ethane is a
gas.
• Methanol and Ethanol are classed as Polar
Molecules (Hydrophilic) – They are Infinitely
Soluble in Water
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Alcohols
• Methanol (CH3OH)
– Solvent in varnishes, paint
– Racing Car Fuel (easy to put out flames)
– Highly Toxic – “Blindness” – Formaldehyde
• Ethanol (C2H5OH)
– Drinking alcohol
– 50% ethanol is flammable
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Alcohols
Thiols
Phenols
•
•
• An aromatic bezene ring with a
hydroxyl substituted for one
hydrogen.
• Widely used as a disinfectant.
• Chlorinated phenols are
important pesticides.
•
•
•
It is also called mercaptans
The sulfur analog of alcohols, “OH” being replaced with “-SH”.
It has unpleasant odor like the
‘rotten egg’
3-methyl-1-butanethiol, one of
the ‘active ingredients’ used by
skunks for self-defense
Important in biochemistry and
are present in living organisms
and decaying matter.
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F. Musico
Ethers
• They have two hydrocarbon groups bound
by an interior oxygen molecule.
• They have solubilities similar to alcohol in
water.
• Ethers are used as gasoline additives to
reduce carbon monoxide emissions. One
such additives is tert-butyl ether (MTBE).
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F. Musico
Aldehydes and Ketones
• Contain carbonyl functional group.
• An aldehyde’s functional group is at one end of
the hydrocarbon chain, bonded to a carbon and a
hydrogen.
• In ketones, the functional group is located
internally with hydrocarbon chains at each end.
• Aldehydes and ketones are both important in the
synthesis of other chemical compounds
• Ketones are also used as industrial solvents.
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Carboxylic Acids
• They are important chemical
intermediaries in the preparation of
several chemicals, including acetic
acid (household vinegar), and they
help in biological degradation.
• They contain acryl group, which is a
carbon double bonded to oxygen.
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Amines
• Amines contain and “-NH2-” group or
compounds in which the “N” is
contained within the carbon chain.
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Amides
R'
R'
N
C
O
------------- Not acids or bases
R
N
C
R
O
Features of a Peptide Bond;
1. Usually inert
2. Planar to allow delocalisation
3. Restricted Rotation about the amide bond
4. Rotation of Groups (R and R’) attached to the amide
bond is relatively free
Engr. Yvonne Ligaya F. Musico
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R
H2N C COOH
H
AMINO ACIDS
O
C
H
NH2
formamide
H3C
O
C
O
NH2
acetamide
NH2
benzamide
O
C
H2N
NH2
urea
All are high melting point solids, only
benzamide not soluble in water
Engr. Yvonne Ligaya F. Musico
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CHEMICALS OF LIFE
"You are chemistry" - all life develops
from and consists of (bio)chemical
processes. Chemistry constitutes the
basis for life. From the first moment and
in every second of our life complex biochemical reactions go on in our body.
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F. Musico
Monomer - building blocks of larger
molecules
Polymers - repeating subunits (monomers)
bonded together
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93
Monomer - building blocks of larger
molecules
Polymers - repeating subunits (monomers)
bonded together
Engr. Yvonne Ligaya F. Musico
94
Dehydration Synthesis - Reactions to form
most large organic molecules. Molecule
of water removed from bond area as
monomers are linked.
Hydrolysis (Digestion) - Large organic
molecules are broken up. Molecule of
water added to help remove the
monomers.
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95
Organic Molecules Found in Living
Organisms
•
•
•
•
Carbohydrates
Proteins
Lipids
Nucleic Acid
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F. Musico
Carbohydrates
• Carbos = Sugars: C, H, O in 1:2:1
ratio (roughly CH2O).
– Monosaccharides
– Disaccharides
– Polysaccharides
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Monosaccharides
• simple sugars (The building block of all larger
sugars.)
Examples of Monosaccharides:
a) Glucose - Form of simple sugar used by all
cells. From grapes & honey. (sweet!)
b) Fructose - Fruit sugar (sweet!)
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Disaccharides
• Double sugar
• Formed by dehydration synthesis (removal
of water as the 2 monosaccharides bond)
Examples of Disaccharides:
a) Maltose = glucose + glucose
b) Sucrose (table sugar) = glucose + fructose
c) Lactose (milk sugar) = glucose +
galactose
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99
Polysaccharides
• starches, chains of sugars
• Formed by dehydration synthesis (removal of
water as all the monosaccharides bond)
Examples of Polysaccharides:
a) Amylose: simple plant starch
b) Pectins: branched plant starch
c) Glycogen: branched animal starch
d) Cellulose: component of plant cell walls,
undigestible by most organisms, human dietary
fiber
Engr. Yvonne Ligaya F. Musico
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Importance of Carbohydrates
a) Glucose - key metabolic fuel (energy source) of all
cells.
b) Animal Starch (Glycogen)- long term energy
storage for animal cells (stores the glucose
molecules in a form not easily used!).
c) Plant Starch (Amylose) - long term energy storage
for plant cells (stores the glucose molecules in a
form that is not easily used!)
d) Cellulose - Structural polysaccharide of cell walls.
e) Chitin - Structural polysaccharide of exoskeletons
of insects and crustaceans.
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F. Musico
Proteins
• They are organic molecules consisting of
many amino acids bonded together.
• Amino Acids – monomers or building
blocks of all proteins
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Denaturation
• protein shape altered with
changes in pH,
temperature.
• Change in shape alters
activity of enzyme.
• Enzymes function within
a narrow range of these
factors.
Nitrogenous Oxygen
Demand (NOD)
• The amount of oxygen
required to convert
ammonia or organic
nitrogen forms into nitrate
[NO3-]
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F. Musico
Functions of Proteins & Named Examples
1) Enzyme catalysis: Enzymes help reactions occur
more easily. Example- Amylase (Converts starch
to simple sugar.)
2) Defense: Antibodies - Globular proteins that
"recognize" foreign microbes.
3) Transport- Hemoglobin (red blood cell protein).
4) Structure / Support- Collagen, which forms the
matrix of skin, ligaments, tendons and bones.
5) Motion- Actin, a muscle protein responsible for
muscle contraction.
6) Regulation- Hormones which serve as
intercellular messengers. Example - Insulin (blood
sugar regulation).
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Lipids
• Organic molecules insoluble in water due
to numerous non-polar C-H bonds.
• Fats, oils, & waxes
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Types of Lipids
•
•
•
•
•
Triglycerides (fats)
Phospholipids
Steroids
Terpenes
Prostaglandins
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NUCLEIC ACID
• Hereditary material
– Deoxyribonucleic acid: DNA, master
molecule, stores hereditary information
– Ribonucleic acid: RNA, template copy
Nucleotides - monomers of nucleic acids.
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DNA Nucleotide
RNA Nucleotide
a) Sugar = deoxyribose
b) Double helix form: two
intertwined chains (double
stranded)
a) Sugar = ribose
b) Uracil (U) replaces thymine (T)
in RNA
Uracil (U) - Adenine (A)
Guanine (G) - Cytosine (C)
c) Single stranded helix
Specific base pairing,
complementary
• Guanine (G) - Cytosine (C)
• Adenine(A) - Thymine (T)
Reference:
Mihelcic, J. and Zimmerman, J. (2012).
Chemistry. Environmental Engineering:
Fundamentals, Sustainability, Design.
John Wiley & Sons, Singapore. pp. 52104.
Masters, G.M., and Ela, W. P. (2008).
Environmental Chemistry. Environmental
Engineering and Science. Prentice Hall.
Pp. 47-86.
Engr. Yvonne Ligaya F. Musico
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