C2, Chapter 1
Answers
Marks
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a transferred
b covalent
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a
b
c
d
simple molecule
giant covalent
metal
giant ionic
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3
a
b
c
d
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a FeCl3
b i Na2S
ii Na2SO4
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Ca2+, OH–
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a i element
ii compound
b It loses an electron.
c i Right hand diagram with seven crosses and one dot in outermost shell
(allow diagram with all crosses).
ii Oppositely charged ions attract each other.
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a Each correctly drawn part of the diagram should be answered (one mark).
• Correctly drawn potassium atom (one electron in outer shell).
• Correctly drawn chlorine atom (seven electrons in outer shell).
• Correctly drawn potassium ion: no electron in outer shell (accept eight
electrons in outer shell) and brackets with  charge top right.
• Correctly drawn chloride ion: eight electrons in outer shell and brackets
with – charge top right.
b For example, H atom: circle with a single dot, Cl atom: circle with seven
crosses overlapping H circle so that a dot and cross are shared or
alternative with no circles. Must be one electron different from seven others
and a shared pair including that electron clearly shown for two marks. One
mark for a shared pair of electrons, or eight electrons all with the same
symbol.
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7
8
Electrons in the highest (occupied) energy level/outer shell are delocalised/
free (to move), leaving or surrounding positive ions (in regular
lattice/arrangement), electrons attract/hold together the positive ions.
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C2, Chapter 2
Answers
Marks
1
a
b
c
d
2
a Layers of atoms can slide/move over each other.
b Zinc atoms are a different size (from copper atoms); they disrupt the
structure, (making it) more difficult/less able to slide/move.
c It returns to its original shape, after being deformed or when the
temperature changes or when it is heated.
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identical, different, thermosoftening
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a Simple molecules or small molecules, weak intermolecular forces or
weak attractions between molecules. Therefore it has a low boiling point.
b There are no bonds/cross-links between polymer molecules or there are
weak intermolecular forces/ attractions between (polymer) molecules,
these weak forces are overcome when the polymer is heated and so it
softens/melts.
2
5
giant covalent
metal
simple molecule
ionic
a Marks awarded for this answer will be determined by the Quality of
Written Communication (QWC) as well as the standard of the scientific
response.
There is a clear and detailed scientific description of why copper has a
high melting point including details of the structure and bonding in a
metal. The answer shows almost faultless spelling, punctuation and
grammar. It is coherent and in an organised, logical sequence. It
contains a range of appropriate and relevant specialist terms used
accurately.
The answer has some structure and the use of specialist terms has been
attempted, but not always accurately. There may be some errors in
spelling, punctuation and grammar. There is a scientific description.
There are some errors in spelling, punctuation and grammar. The answer
has some structure and organisation. The use of specialist terms has
been attempted, but not always accurately.
There is a brief description of the structure of a metal . The spelling,
punctuation and grammar are very weak. The answer is poorly organised
with almost no specialist terms and/or their use demonstrating a general
lack of understanding of their meaning.
No relevant content.
Examples of the chemistry points made in the response:
• giant structure/lattice
atoms arranged in a regular pattern or in layers
• sea of electrons or delocalised electrons or free electrons
• awareness that outer shell/highest energy level electrons are
involved
• positive ions
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C2, Chapter 2
Answers
Marks
•
•
•
(electrostatic) attractions/bonds between electrons and positive ions
bonds/attractions (between atoms or ions and electrons) are strong
a lot of energy/heat is needed to break these bonds/attractions.
b i The tubes are very small (not ‘small’ on its own), or a few atoms
across, or they are 1–100 nm across.
ii Three electrons in carbon’s outer shell are used in bonding, which
leaves one electron free to move around or delocalise and carry
current or charge.
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C2, Chapter 3
Answers
Marks
1
a i
ii
iii
b i
ii
2
a Give two marks for 157. If answer is incorrect either 2 × 19 + 119 or 119
+ 19 = 138 gains one mark.
b Give two marks for 24.2 (accept answers in the range 24 to 24.2038). If
the answer is incorrect, 25 or 38/157 × 100 or 19/157 × 100 = 12 to 12.1
or 19/138 × 100 gains one mark (allow error carried forward from part a
so 38/a × 100 gains two marks if calculated correctly).
c 0.29 (accept answers in the range 0.28 to 0.3 and allow error carried
forward from part b)
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3
a Reversible (reaction). (Accept reaction goes both ways).
b Heating: causes (thermal) decomposition or forward reaction and so
produces gases (ammonia gas and hydrogen chloride gas or NH3 and
HCl). The gases are cooled near the top of the test tube, which causes
the reverse reaction and so solid ammonium chloride is formed.
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a i
ii
iii
b i
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1
1
2
5
15
16
15
isotopes
One from: different mass (numbers), (number of) neutrons, total
number of (subatomic) particles, (physical) properties (but do not
allow chemical properties).
the column
the mass spectrometer
the computer
Give two marks for 165. If the answer is incorrect then evidence of
correct working gains one mark, e.g. 10 × 12 + 15 + 14 + 16.
ii Give two marks for 10.37%. If the answer is incorrect, then evidence
of correct working gains one mark.
14
 100%  10.37%
135
iii Two from: faster, more accurate, detects smaller amounts.
a Give two marks for 83.7 (percent). (Accept answers in the range 83.72
to 84.) If the answer is incorrect, evidence of correct working gains one
mark, e.g. 6 × 12/(6 × 12 + 14) × 100.
b Give one mark for each correct step: one mark for mass of hydrogen –
(100 g of hydrocarbon contains 85.7 g C and 14.3 g H); one mark for
dividing masses by correct Ar – 85.7/12 and 14.3/1; one mark for correct
proportions – 7.14… and 14.3 or simplified ratio 1:2; 1 mark for correct
empirical formula CH2.
c Accept ‘no’ with a valid explanation – e.g. because the empirical formula
is different/that of an alkene or it gives C6H12 for six carbon atoms or it
is not an alkane or because the percentage of carbon is different and
compounds have fixed proportions (of elements). Accept the answer
that one cannot be sure if there is a valid explanation, e.g. because of
experimental error or only one result or one needs to confirm the result
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C2, Chapter 3
Answers
Marks
or to repeat the test. Do not accept yes.
New AQA GCSE Science © Nelson Thornes Ltd 2011
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C2, Chapter 4
Answers
Marks
1
a increase
b i decreases
ii increases
c It gives the particles more energy. It makes the particles move faster.
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1
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2
a The bag gets cold because heat is taken in from the surroundings.
b Two from: mix/spread (the ammonium nitrate and water), so the whole
bag gets cold; dissolve faster; get cold faster; particles collide more or
more collisions (allow increase rate or quicker reaction).
2
2
3
a Two from: rate is high at the start (allow fast at the start), decreases with
time until it becomes zero.
b Use zinc powder.
c More particles in given volume or particles closer together/more
crowded; particles collide more frequently or more often.
d Three from: speed of particles increases; more frequent collisions; more
energetic collisions; more particles have activation/minimum energy
(needed) to react.
2
a Two from: not used up in reaction or does not need replacing very often;
only a small amount is needed or very effective; catalyses many
reactions.
b There is a greater surface area of catalyst/metal and so particles of
reactants collide with the surface (of catalyst/ metal) more frequently.
c Economic: low(er) cost of cobalt (relative to platinum). Environmental:
sensible suggestion, e.g. cobalt (may be) less toxic/harmful (to living
things); cobalt mining causes less damage (because there is a higher
percentage of cobalt in ores).
d Three from: increases rate of reaction; more product in less time;
reduces costs; less energy needed; less fossil fuel needed (for
energy/heating/pressure); smaller workforce.
2
4
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C2, Chapter 5
Answers
Marks
1
a B
b 1
c i alkali
ii neutralisation
iii sodium chloride
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1
1
2
a A white precipitate or a white solid.
b lead nitrate + sodium chloride → lead chloride + sodium nitrate (reactants
for one mark, products for one mark)
c Add sodium chloride or any other soluble salt that will give a precipitate
with lead ions or a named alkali; allow to settle or filter.
1
2
3
There is a clear and detailed scientific description of how to prepare
copper(II) sulfate solution from copper(II) oxide and dilute sulfuric acid and
how to obtain crystals from the solution with five or six points from the
examples given. The answer shows almost faultless spelling, punctuation
and grammar. It is coherent and in an organised, logical sequence. It
contains a range of appropriate and relevant specialist terms used
accurately.
There is a scientific description of the preparation of copper(II) sulfate with
three or four points from the examples given. There are some errors in
spelling, punctuation and grammar. The answer has some structure and
organisation. The use of specialist terms has been attempted but not always
accurately.
4
2
5-6
3-4
There is a brief description of the reaction of copper(II) oxide with an acid or
of crystallisation of a solution of copper(II) sulfate with one or two points from
the examples given. The spelling, punctuation and grammar are very weak.
The answer is poorly organised with almost no specialist terms and/or their
use demonstrating a general lack of understanding of their meaning.
1-2
No relevant content.
Examples of the chemistry points made in the response:
• Use dilute sulfuric acid.
• Place acid in a beaker.
• Warm the acid.
• Add copper(II) oxide.
• In small amounts.
• Until in excess or there is no further reaction.
• Filter (to remove excess copper(II) oxide).
• Heat filtrate/solution to evaporate some water.
• Allow solution to cool and crystallise or allow to evaporate slowly at room
temperature.
• Remove/filter crystals from remaining solution.
0
a Two from: ions can move in solution; opposite charges attract; silver ions
are positive and spoon is negative.
b gaining an electron
2
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C2, Chapter 5
Answers
5
Marks
c Any sensible suggestion – e.g. better appearance; less toxic; less likely to
corrode; less expensive than solid silver.
1
a i Sensible suggestion – e.g. high melting point; strong; can be shaped;
holds (hot) liquid, does not react with liquid (magnesium
chloride/magnesium); low cost; at high temperature carbon electrode
would burn with oxygen from the air to produce carbon dioxide.
ii Sensible suggestion – e.g. does not react with chlorine; high melting
point; low cost (but do not accept if low cost already allowed in i).
b i Less heat/energy needed or lower cost of energy (accept less heat
lost).
ii Less fossil fuel burned (for heat/energy) so less pollution; less global
warming; resources conserved; less mining (must be linked) or less
thermal; heat pollution.
c i Mg2+ + 2e– → Mg
ii Cl– → Cl2 + 2e–
1
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