Questions
Q1.
The table shows some properties of six compounds.
compound
melting point
/ °C
boiling point
/ °C
solubility in
water
copper sulfate
200
decomposes
soluble
hexane
–95
69
insoluble
hydrogen
chloride
–112
–85
soluble
electrical
conductivity
of solution
high
does not
dissolve
high
does not
dissolve
does not
silicon(IV) oxide 1610
2230
insoluble
dissolve
sodium chloride
801
1413
soluble
high
(a) Which of the following lists of compounds from the table contains only ionic compounds?
Put a cross (
) iin the box next to your answer.
octane
–57
126
insoluble
(1)
A copper sulfate, octane and sodium chloride
B silicon(IV) oxide and sodium chloride
C copper sulfate and sodium chloride
D copper sulfate and silicon(IV) oxide
(b) Two of the compounds in the table produce a colour in a flame test.
Give the name of one of these compounds and the colour it produces in the flame test.
(2)
compound . . . . . . . . . . . . . . . . . . . .
colour . . . . . . . . . . . . . . . . . . . .
(c) Hexane is a covalent compound containing simple molecules.
It has a low boiling point.
(i) Explain why it has a low boiling point.
(2)
(ii) Hexane and water are immiscible.
Describe how separate samples of hexane and water can be obtained from a mixture of hexane and
water.
(2)
(d) Draw a dot and cross diagram of a molecule of hydrogen chloride.
Show outer electrons only.
(2)
(Total for Question is 9 marks)
Q2.
Oxygen is a simple molecular, covalent substance.
(i) The electronic configuration of oxygen is 2.6.
Draw a dot and cross diagram for a molecule of oxygen, O2.
Show the outer electrons only.
(3)
(ii) The boiling point of oxygen is –183 °C.
Explain, in terms of the forces between the molecules, why oxygen has a very low boiling point.
(2)
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Q3.
Structures
The table shows some properties of diamond and graphite.
diamond
graphite
colourless crystals
black, shiny solid
very hard
flakes easily
does not conduct electricity
conducts electricity
(a) (i) Suggest why diamond and graphite might be expected to have similar properties.
(1)
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(ii) By referring to its structure, explain why diamond is very hard.
(3)
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(iii) By referring to its structure, explain why graphite flakes easily.
(2)
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(b) Complete the sentence by putting a cross ( ) in the box next to your answer.
Carbon dioxide is a gas at room temperature.
A carbon dioxide molecule is a
(1)
A giant molecule that has covalent bonds
B giant molecule that has ionic bonds
C simple molecule that has covalent bonds
D simple molecule that has ionic bonds
(c) The atomic number of carbon is 6 and of fluorine is 9.
Carbon and fluorine atoms are combined in a tetrafluoromethane molecule, CF4.
Draw a dot and cross diagram of a tetrafluoromethane molecule.
Show outer electrons only.
(2)
Mark Scheme
Q1.
Answer
(a)
(b)
C : copper sulfate
and sodium chloride
copper sulfate (1)
blue-green (1) or
sodium chloride (1)
yellow (1) colour
mark consequential
Acceptable
answers
Mark
(1)
allow blue or green
or greenblue
reject orange
and yellow-orange
(2)
(c)(i)
(c)(ii)
on correct metal
(compound)
An explanation
linking weak
intermolecular
forces /weak forces
between molecules
(1)
little heat /
energy needed to
separate (molecules)
(1)
A description linking
use separating
funnel (1)
run off
lower layer / liquid /
OWTTE (1)
(d)
shared pair in
molecule (1)
rest of molecule
consequent on first
mark (1)
bonds / attractions
in place of forces
intermolecular forces
between atoms /
bonds loses 1st
marking point any
answer in terms of
covalent or ionic
bonding scores zero
alternative
description of
separating funnel eg
funnel with a tap at
the bottom suitable
labelled diagram
burette allow layers
/ liquids to separate
ignore fractional
distillation
Allow a diagram
without labels for 2
marks
any
symbols shown must
be correct for the 2nd
mark allow any
combination of dots
and crosses for
electrons wrong
compound = zero
marks
(2)
Acceptable
answers
ignore any inner
electrons shown
3rd Mark is
dependent on 2nd
Mark
(2)
(2)
Q2.
Answer
(i)
(ii)
 electrons shared
/ between atoms (1)
 2 pairs of/four
electrons shared /
between two atoms
(1)
 4 additional
electrons on both
oxygen atoms (1)
An explanation
linking the following
second marking
point is dependent
on the first
 forces (between
the molecules) are
weak (1)
 therefore little
(3)
(2)
intermolecular
forces/bonds
between molecules
reject intramolecular
force/covalent
bond/ionic bond
heat/energy needed
to separate
molecules/break
these forces (1)
Q3.
Question
Number
(a)(i)
Question
Number
(a)(ii)
Question
Number
(a)(iii)
Question
Number
(b)
Question
Number
(c)
Answer
Acceptable answers
Mark
both (pure forms of)
carbon / both giant
molecular
Answer
Acceptable answers
(1)
Mark
An explanation
linking three of the
following points
• (every) carbon
atom forms four
bonds (1) • strong
bonds / hard to
separate atoms from
lattice (1) • covalent
bonds (1) • covalent
bonds (1)
Answer
Acceptable answers
(3)
Mark
An explanation
linking the following
• (in) layers (1)
• weak forces
between layers (1)
Answer
Acceptable answers
(2)
Mark
Acceptable answers
(1)
Mark
C
Answer
• four bonding pairs
shown (1) • six non
bonded electrons on
each fluorine atom
(1)
(2)