GCSE

CHEMISTRY
8462/1H
Paper 1 Higher Tier
Mark scheme
June 2020
Version: 1.0 Final Mark Scheme

*206G8462/1H/MS*
 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Mark schemes are prepared by the Lead Assessment Writer and considered, together with the relevant
questions, by a panel of subject teachers. This mark scheme includes any amendments made at the
standardisation events which all associates participate in and is the scheme which was used by them in
this examination. The standardisation process ensures that the mark scheme covers the students’
responses to questions and that every associate understands and applies it in the same correct way.
As preparation for standardisation each associate analyses a number of students’ scripts. Alternative
answers not already covered by the mark scheme are discussed and legislated for. If, after the
standardisation process, associates encounter unusual answers which have not been raised they are
required to refer these to the Lead Examiner.

It must be stressed that a mark scheme is a working document, in many cases further developed and
expanded on the basis of students’ reactions to a particular paper. Assumptions about future mark
schemes on the basis of one year’s document should be avoided; whilst the guiding principles of
assessment remain constant, details will change, depending on the content of a particular examination
paper.

Further copies of this mark scheme are available from aqa.org.uk

Copyright information

AQA retains the copyright on all its publications. However, registered schools/colleges for AQA are permitted to copy material from this booklet for their own
internal use, with the following important exception: AQA cannot give permission to schools/colleges to photocopy any material that is acknowledged to a third
party even for internal use within the centre.

Copyright © 2020 AQA and its licensors. All rights reserved.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Information to Examiners

1. General

The mark scheme for each question shows:

• the marks available for each part of the question
• the total marks available for the question
• the typical answer or answers which are expected
• extra information to help the Examiner make his or her judgement
• the Assessment Objectives, level of demand and specification content that each question is intended
to cover.

The extra information is aligned to the appropriate answer in the left-hand part of the mark scheme and
should only be applied to that item in the mark scheme.

At the beginning of a part of a question a reminder may be given, for example: where consequential
marking needs to be considered in a calculation; or the answer may be on the diagram or at a different
place on the script.

In general the right-hand side of the mark scheme is there to provide those extra details which confuse
the main part of the mark scheme yet may be helpful in ensuring that marking is straightforward and
consistent.

2. Emboldening and underlining

2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is used, with
the number of marks emboldened. Each of the following bullet points is a potential mark.

2.2 A bold and is used to indicate that both parts of the answer are required to award the mark.

2.3 Alternative answers acceptable for a mark are indicated by the use of or. Different terms in the
mark scheme are shown by a / ; eg allow smooth / free movement.

2.4 Any wording that is underlined is essential for the marking point to be awarded.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

3. Marking points
3.1 Marking of lists

This applies to questions requiring a set number of responses, but for which students have
provided extra responses. The general principle to be followed in such a situation is that ‘right +
wrong = wrong’.

Each error / contradiction negates each correct response. So, if the number of error /
contradictions equals or exceeds the number of marks available for the question, no marks can be
awarded.

However, responses considered to be neutral (indicated as * in example 1) are not penalised.

Example 1: What is the pH of an acidic solution?

[1 mark]

Student Response Marks

awarded
1 green, 5 0
2 red*, 5 1
3 red*, 8 0

Example 2: Name two planets in the solar system.

[2 marks]

Student Response Marks awarded

1 Neptune, Mars, Moon 1
2 Neptune, Sun, Mars, 0
Moon

3.2 Use of chemical symbols / formulae

If a student writes a chemical symbol / formula instead of a required chemical name, full credit can
be given if the symbol / formula is correct and if, in the context of the question, such action is
appropriate.

3.3 Marking procedure for calculations

Marks should be awarded for each stage of the calculation completed correctly, as students are
instructed to show their working. Full marks can, however, be given for a correct numerical
answer, without any working shown.

3.4 Interpretation of ‘it’

Answers using the word ‘it’ should be given credit only if it is clear that the ‘it’ refers to the correct
subject.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

3.5 Errors carried forward

Any error in the answers to a structured question should be penalised once only.

Papers should be constructed in such a way that the number of times errors can be carried forward
is kept to a minimum. Allowances for errors carried forward are most likely to be restricted to
calculation questions and should be shown by the abbreviation ecf in the marking scheme.

3.6 Phonetic spelling

The phonetic spelling of correct scientific terminology should be credited unless there is a possible
confusion with another technical term.

3.7 Brackets

(…..) are used to indicate information which is not essential for the mark to be awarded but is
included to help the examiner identify the sense of the answer required.

3.8 Allow

In the mark scheme additional information, ‘allow’ is used to indicate creditworthy

alternative answers.

3.9 Ignore

Ignore is used when the information given is irrelevant to the question or not enough to gain the
marking point. Any further correct amplification could gain the marking point.

3.10 Do not accept

Do not accept means that this is a wrong answer which, even if the correct answer is given as
well, will still mean that the mark is not awarded.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

4. Level of response marking instructions

Extended response questions are marked on level of response mark schemes.
• Level of response mark schemes are broken down into levels, each of which has a descriptor.
• The descriptor for the level shows the average performance for the level.
• There are two marks in each level.

Before you apply the mark scheme to a student’s answer, read through the answer and annotate it
(as instructed) to show the qualities that are being looked for. You can then apply the mark scheme.

Step 1: Determine a level

Start at the lowest level of the mark scheme and use it as a ladder to see whether the answer meets
the descriptor for that level. The descriptor for the level indicates the different qualities that might be
seen in the student’s answer for that level. If it meets the lowest level then go to the next one and
decide if it meets this level, and so on, until you have a match between the level descriptor and the
answer.

When assigning a level you should look at the overall quality of the answer. Do not look to penalise
small and specific parts of the answer where the student has not performed quite as well as the rest.
If the answer covers different aspects of different levels of the mark scheme you should use a best
fit approach for defining the level.

Use the variability of the response to help decide the mark within the level, ie if the response is
predominantly level 2 with a small amount of level 3 material it would be placed in level 2 but be
awarded a mark near the top of the level because of the level 3 content.

Step 2: Determine a mark

Once you have assigned a level you need to decide on the mark. The descriptors on how to
allocate marks can help with this.

The exemplar materials used during standardisation will help. There will be an answer in the
standardising materials which will correspond with each level of the mark scheme. This answer will
have been awarded a mark by the Lead Examiner. You can compare the student’s answer with the
example to determine if it is the same standard, better or worse than the example. You can then
use this to allocate a mark for the answer based on the Lead Examiner’s mark on the example.

You may well need to read back through the answer as you apply the mark scheme to clarify points
and assure yourself that the level and the mark are appropriate.

Indicative content in the mark scheme is provided as a guide for examiners. It is not intended to be
exhaustive and you must credit other valid points. Students do not have to cover all of the points
mentioned in the indicative content to reach the highest level of the mark scheme.

You should ignore any irrelevant points made. However, full marks can be awarded only if there are
no incorrect statements that contradict a correct response.

An answer which contains nothing of relevance to the question must be awarded no marks.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 1

AO /
Question Answers Extra information Mark
Spec. Ref.

01.1 poly(ethene) 1 AO2

4.2.1.4
water 1 4.2.2.4
4.2.2.5

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 1 continued

AO/
Question Answers Mark
Spec. Ref
01.2 Level 2: Scientifically relevant features are identified; the way(s) in 4–6 AO1
which they are similar/different is made clear and (where 4.2.1.2
appropriate) the magnitude of the similarity/difference is noted. 4.2.1.3
4.2.1.4

Level 1: Relevant features are identified and differences noted. 1–3

No relevant content 0

Indicative content

• (both) carbon dioxide and silicon dioxide are made up of atoms

• (but) magnesium oxide is made up of ions

• (both) silicon dioxide and magnesium oxide are giant structures

• (but) carbon dioxide is small molecules
• with weak intermolecular forces

• all three compounds have strong bonds

• (both) carbon dioxide and silicon dioxide are formed from two
non-metals
• (so) bonds formed are covalent
• (so) electron (pairs) are shared (between atoms)
• (but) magnesium oxide is formed from a metal and a non-metal
• (so) bonds in magnesium oxide are ionic
• (so) electrons are transferred
• from magnesium to oxygen
• two electrons are transferred

• bonds in silicon dioxide are single bonds

• (where) each silicon forms four bonds
• (and) each oxygen forms two bonds
• (but) in carbon dioxide the bonds are double bonds
• (where) carbon forms two double bonds
• (and) oxygen forms one double bond

ignore properties e.g. melting point, electrical conductivity

Total 8

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 2

AO /
Question Answers Extra information Mark
Spec. Ref.

02.1 they form ions with different 1 AO1

charges 4.1.3.1
4.1.3.2
they have high melting points 1

02.2 the (grey) crystals are silver 1 AO3

4.4.1.2
the copper ions (produced) are allow the copper nitrate / 1
blue compound (produced) is blue

(because) copper displaces 1

silver

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 2 continued

AO/
Question Answers Mark
Spec. Ref
Level 2: The method would lead to the production of a valid AO1
02.3 3–4
outcome. The key steps are identified and logically sequenced. AO3
4.4.1.2
Level 1: The method would not lead to a valid outcome. Some 4.5.1.1
1–2
relevant steps are identified, but links are not made clear. RPA 4

No relevant content 0

Indicative content

Key steps
• add the metals to (dilute) hydrochloric acid

• measure temperature change

or
compare rate of bubbling
or
compare colour of resulting solution

for copper:
• no reaction
• shown by no temperature change
or
shown by no bubbles

for magnesium and iron:

• magnesium increases in temperature more than iron
or
magnesium bubbles faster than iron
or
magnesium forms a colourless solution and iron forms a coloured
solution

Control variables
• same concentration / volume of hydrochloric acid
• same mass / moles of metal
• same particle size of metal
• same temperature (of acid if comparing rate of bubbling)

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 2 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

02.4 AO2
(203 × 30) + (205 × 70) 1 4.1.1.6
100
or

6090 + 14 350
100

= 204.4 ignore units 1

Total 11

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 3

AO /
Question Answers Extra information Mark
Spec. Ref.

03.1 (total) mass before = 156.76 (g) allow 78.26 + 78.50 = 156.76 1 AO2
and and
(total) mass after = 156.76 (g) 108.22 + 48.54 = 156.76

or

increase in mass of beaker A allow 108.22 – 78.26 = 29.96

and contents = 29.96 (g) and
and 48.54 – 78.50 = – 29.96
decrease in mass of beaker B
and contents = 29.96 (g)

(so) the mass of products allow (so) no atoms were lost or 1 AO1
equals the mass of the reactants made during the reaction
or
4.3.1.1
(so) there is no change in mass
during the reaction

03.2 filter / filtration allow a description of filtration 1 AO2

4.1.1.2

03.3 allow correct formulae AO2

4.1.1.2
sodium nitrate (solution) allow sodium / nitrate / silver / 1
or iodide ions
silver nitrate (solution)
or
sodium iodide (solution)

03.4 to remove / evaporate the water allow to dry (the solid) 1 AO3
4.1.1.2

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 3 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

03.5 AO2
(total Mr = 170 + 150) = 320 allow (235 + 85) = 320 1 4.3.3.2

(% atom economy =)
235 allow correct use of incorrectly 1
×100 calculated total Mr
320

1
= 73.4375 (%)

= 73.4 (%) allow an answer correctly 1

calculated to 3 significant figures
from an incorrect percentage
calculation which uses the
values in the question

03.6 any one from: 1 AO1

4.3.3.2
• for sustainable development allow to reduce waste
• for economic reasons
• to produce a high(er)
percentage of useful product

Total 10

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 4

AO /
Question Answers Extra information Mark
Spec. Ref.

allow anode for positive

04.1 electrode

CrO42- / chromate ions moved to allow yellow (coloured) ions 1 AO2

the positive electrode moved to the positive electrode

(because) opposite charges allow (because) negative ions 1 AO1

attract are attracted to the positive
electrode 4.4.3.1
RPA 3

water ignore copper chromate solution 1 AO1

04.2 4.4.3.4
RPA 3

copper ions gain two electrons allow Cu2+ for copper ions 2 AO2
04.3
allow 1 mark for copper ions
gain electrons
or
allow 1 mark for copper ions are
reduced

do not accept copper ions are

oxidised

(to) form copper (atoms) allow Cu for copper (atoms) 1 AO3

the equation: 4.4.3.1

Cu2+ + 2e- → Cu 4.4.3.4
scores 3 marks RPA 3

(negative electrode) hydrogen allow H2 1 AO2

04.4 4.4.3.4
(positive electrode) iodine allow I2 1 RPA 3

Total 8

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 5

AO /
Question Answers Extra information Mark
Spec. Ref.

05.1 any three from: 3 AO1

(nuclear model) 4.1.1.3
• mostly empty space allow the plum pudding model
has no empty space
allow the plum pudding model is
solid

• the positive charge is (all) in allow in the plum pudding model

the nucleus the atom is a ball of positive
charge (with embedded
electrons)
do not accept reference to
protons

• the mass is concentrated in allow in the plum pudding model

the nucleus the mass is spread out
do not accept reference to
neutrons

• the electrons and the nucleus allow in the plum pudding model
are separate the electrons are embedded
allow in the nuclear model the
electrons are in orbits

05.2 do not accept reference to AO1

protons / neutrons 4.1.1.3

electrons orbit the nucleus allow electrons are in energy 1

levels around the nucleus
or
allow electrons are in shells
around the nucleus
electrons are at specific 1
distances from the nucleus

05.3 atomic number is the number of 1 AO3

protons 4.1.1.3
4.1.1.4
(and) protons were not ignore electrons / neutrons were 1 4.1.2.2
discovered until later not discovered until later

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 5 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

05.4 so their properties matched the allow converse 1 AO1

rest of the group 4.1.2.2

Total 8

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 6

AO /
Question Answers Extra information Mark
Spec. Ref.

06.1 the (minimum) energy needed 1 AO1

for particles to react 4.5.1.2
or
the (minimum) energy needed allow the (minimum) energy
for a reaction to occur needed to start a reaction

06.2 (Mr of Fe2O3 =) 160 1 AO2

4.3.1.2
4.3.2.1
4.3.2.2
(moles Fe2O3 =
3000
=) 4.3.2.4
160
18.75 (mol) allow correct use of incorrectly 1
calculated Mr

1000
(moles Al = =) 37.0 (mol) allow 37.037037 (mol) correctly 1
27
rounded to at least 2 significant
figures

if both MP2 and MP3 are not

awarded allow 1 mark for
0.01875 mol Fe2O3 and 0.037
mol Al

(aluminium is limiting because) allow correct use of incorrect 1

37.0 mol is less than the (2 x number of moles from steps 2
18.75 =) 37.5 mol (aluminium and/or 3
needed)
or
iron oxide is in excess because
18.75 mol is more than the
37.0
( =) 18.5 mol (iron oxide
2
needed)

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 6 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

06.2 alternative approaches: AO2

ctd 4.3.1.2
approach 1: 4.3.2.1
(finding required mass of 4.3.2.2
aluminium by moles method) 4.3.2.4

(Mr of Fe2O3 =) 160 (1)

3000
(moles Fe2O3 = =)
160
18.75 (mol) (1) allow correct use of incorrectly
calculated Mr

(moles Al needed
=18.75 × 2 = ) 37.5 (mol) allow correct use of incorrectly
and calculated moles of iron oxide
(mass Al needed = 37.5 × 27 =)
1012.5 (g) or 1.0125 kg (1) allow correct use of incorrectly
calculated moles of aluminium
needed

(so) 1.00 kg of aluminium is not dependent on calculated mass

enough (1) of aluminium needed being
greater than 1.00 (kg)

approach 2:
(finding required mass of
aluminium by proportion
method)

(Mr of Fe2O3 =) 160 (1)

(3.00 kg Fe2O3 needs)

3.00
× 2 × 27 (kg Al) (1) allow correct use of incorrectly
160
calculated Mr
(=) 1.0125 (kg) (1)

(so) 1.00 kg of aluminium is not dependent on calculated mass

enough (1) of aluminium needed being
greater than 1.00 (kg)

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 6 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

06.2 alternative approaches: AO2

ctd 4.3.1.2
approach 3: 4.3.2.1
(finding required mass of iron 4.3.2.2
oxide by moles method) 4.3.2.4

Mr of Fe2O3 =) 160 (1)

1000
(moles Al = =) 37.0 (mol) allow 37.037037 (mol) correctly
27
rounded to at least 2 significant
(1)
figures

37.0
(moles Fe2O3 needed) = )=
2
18.5 (mol) allow correct use of incorrectly
and calculated moles of aluminium
(mass Fe2O3 needed =
18.5 × 160 =) 2960 (g) or allow correct use of incorrectly
2.96 (kg) (1) calculated moles of iron oxide
needed
allow correct use of incorrectly
calculated Mr

(so) 3.00 kg of iron oxide is an dependent on calculated mass

excess (1) of iron oxide needed being less
than 3.00 (kg)

approach 4:
(finding required mass of iron
oxide by proportion method)

(Mr of Fe2O3 =) 160 (1)

1.00
(1.00 kg Al needs) ×160 allow correct use of incorrectly
2 x 27
(kg Fe2O3) (1) calculated Mr

(=) 2.96 (kg) (1)

(so) 3.00 kg of iron oxide is an dependent on calculated mass

excess (1) of iron oxide needed being less
than 3.00 (kg)

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 6 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

06.3 Mg(s) + Zn2+(aq) → allow multiples 2 AO2

Mg2+(aq) + Zn(s) 4.1.1.1
4.2.2.2
allow 1 mark for Mg2+ + Zn 4.4.1.4
with missing or incorrect state
symbols

06.4 magnesium (atoms) are 1 AO2

oxidised because they lose 4.4.1.4
electrons

(and) zinc (ions) are reduced 1

because they gain electrons

if no other marks awarded allow

1 mark for magnesium (atoms)
lose electrons and zinc (ions)
gain electrons

Total 9

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 7

AO /
Question Answers Extra information Mark
Spec. Ref.

07.1 the activation energy should be ignore description of where the 1 AO3
from the reactants (line to the activation energy is on the 4.5.1.2
peak) diagram

the products (line) should be allow the product (line) is above 1

below the reactants (line) the reactants (line)
or
the products should have less allow the products have more
energy than the reactants energy than the reactants
allow the profile shows an
endothermic reaction

ignore the arrow for the overall

energy change should point
downwards

07.2 any two from: allow converse arguments for a 2 AO1

(hydrogen fuel cells) rechargeable cell 4.5.2.2

• no toxic chemicals to dispose

of at the end of the cell’s life

• take less time to refuel (than

to recharge rechargeable
cells)

• travel further before refuelling allow has a greater range

(than before recharging
rechargeable cells)

• no loss of efficiency (over allow does not lose capacity /

time) range in cold weather

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 7 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

07.3 allow multiples 1 AO1

4.5.2.2
any one from:
• H2 → 2 H+ + 2 e- allow H2 - 2 e- → 2 H+
• O2 + 4 H+ + 4 e- → 2 H2O allow H2 + 2 OH- - 2 e- → 2 H2O

• H2 + 2 OH- → 2 H2O + 2 e-

• O2 + 2 H2O + 4 e- → 4 OH-

07.4 any two from: 2 AO1

• hydrogen is not shown as H2 / 4.2.2.1
molecules
• particles are shown as
spheres
• particles are shown as solid
• does not show the (weak)
forces (between particles)
• does not show the movement
/ speed (of particles)
• is only two-dimensional

07.5 any one from: 1 AO3

• under (higher) pressure allow increase concentration 4.2.2.1
• cool allow condense 4.5.2.2
• absorb / adsorb in a solid
allow store as a liquid / solid
allow develop more efficient
engines

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 7 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

07.6 AO2
(58 MJ =) 58 000 kJ allow (58 MJ =) 58 000 000 J 1 4.3.2.1
or and 4.3.5
(290 kJ =) 0.290 MJ (290 kJ =) 290 000 J 4.5.2.2

(moles =
58000
or
58
= ) 200 allow correct use of an 1
290 0.290
incorrectly converted or
unconverted value of energy

(volume =) 200 × 24 allow correct use of an 1

incorrectly calculated number of
moles of hydrogen

= 4800 (dm3) 1

alternative approach:

(58 MJ =) 58 000 kJ (1)

(energy released per dm3 =

290
=) 12.08333 (kJ/dm3) (1)
24

58000
(volume =) (1) allow correct use of an
12.08333
incorrectly converted or
unconverted value of energy

allow correct use of an

incorrectly calculated energy
released per dm3
= 4800 (dm3) (1)

Total 12

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 8

AO /
Question Answers Extra information Mark
Spec. Ref.

08.1 liquid gas 1 AO2

4.2.2.1

08.2 (boiling point) increases (down 1 AO1

the table / group) 4.1.2.6
4.2.2.1
(because) the relative formula / 1 4.2.2.4
molecular mass increases
or
(because) the size of the
molecule increases

(so) the intermolecular forces allow (so) the forces between 1

increase (in strength) molecules increase (in strength)

(so) more energy is needed to allow (so) more energy is 1

overcome the intermolecular needed to separate the
forces molecules

do not accept a reference to

breaking bonds unless
specifically between molecules

08.3 boiling point is a bulk property allow boiling point is related to 1 AO1
intermolecular forces (so more 4.2.2.1
than one molecule is involved)

08.4 the gas / halogen is toxic allow the gas / halogen is 1 AO3
poisonous / harmful 4.1.2.6
allow to prevent inhalation of the
gas / halogen

ignore deadly / lethal

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Question 8 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

08.5 allow energy level for shell AO1

throughout 4.1.2.6

(going down the group) allow the atoms become larger 1

the outer electrons / shell allow the number of shells
become further from the nucleus increases

ignore the number of outer

shells increases

(so) the nucleus has less allow (so) the nucleus has less 1
attraction for the outer electrons attraction for the incoming
/ shell electron

allow (so) increased shielding

between the nucleus and the
outer electrons / shell

allow (so) increased shielding

between the nucleus and the
incoming electron

(so) an electron is gained less 1

easily

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 8 continued

08.6 4.48 (g iron) and 8.52 (g 1 AO2

chlorine) 4.1.1.1
4.1.2.6
(moles Fe =
4.48
=) 0.08 allow correct calculation using 1 4.3.2.3
56
incorrectly calculated mass of
iron

(moles Cl =
8.52
=) 0.24 allow correct calculation using 1
35.5
incorrectly calculated mass of
chlorine
8.52
allow (moles Cl2 = =) 0.12
71

(Fe : Cl = 0.08 : 0.24 =) 1 : 3 allow correct calculation using 1

incorrectly calculated moles of
iron and / or chlorine

2 Fe + 3 Cl2 → 2 FeCl3 allow multiples / fractions 2

allow a correctly balanced

equation including Fe and Cl2
from an incorrect ratio of Fe : Cl

allow 1 mark for Fe and Cl2

(reactants) and FeCl3 (product)
or
allow 1 mark for Fe and Cl2
(reactants) and a formula for
iron chloride correctly derived
from an incorrect ratio of Fe : Cl
(product)

Total 16

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 9

AO /
Question Answers Extra information Mark
Spec. Ref.

09.1 didn’t stir (the solution enough) allow measured the temperature 1 AO3
before the temperature stopped 4.5.1.1
falling RPA 4
allow measured the temperature
too soon

09.2 the temperature decreases allow temperature decreases 1 AO2

(initially) because energy is (initially) because the reaction is AO3
taken in (by the reaction from endothermic 4.5.1.1
the solution) RPA 4

when 1.5 g (of citric acid) is allow when the temperature 1

added the sodium reaches 11.6 °C the sodium
hydrogencarbonate has all hydrogencarbonate has all
reacted reacted

or
from 1.5 g the citric acid is in allow after the temperature
excess reaches 11.6 °C the citric acid is
in excess
or
when 1.5 g (of citric acid) is allow when the temperature
added the reaction is complete reaches 11.6 °C the reaction is
complete

(so) the temperature increases allow (so) the temperature 1

as energy is transferred from the increases as energy is
room to the solution transferred from the excess
citric acid to the solution

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 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 9 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

09.3 less steep line starting at ignore any part of the line drawn 1 AO3
16.8 °C and reaching 1.00 g (of beyond 1.00 g 4.2.2.8
citric acid) 4.5.1.1
RPA 4
(as) metal is a better conductor allow (as) polystyrene is a better 1
insulator

(so) more energy is absorbed allow (so) more heat is 1

(from the surroundings) absorbed (from the
surroundings)

09.4 (Mr citric acid =) 192 1 AO2

4.3.2.5
250 4.3.4
(moles = × 0.0500)
1000
= 0.0125 1

(mass = 0.0125 × 192 =) 2.4 (g) allow correct use of an 1

incorrectly calculated Mr
allow correct use of an
incorrectly calculated number of
moles

alternative approach:

(Mr citric acid =) 192 (1)

(concentration = 0.0500 × 192)

= 9.6 (g/dm3) (1) allow correct use of an
incorrectly calculated Mr

250
(mass = × 9.6 =) 2.4 (g) (1) allow correct use of an
1000
incorrectly calculated
concentration in g/dm3

28
 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 9 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

09.5 add the citric acid (to the flask) ignore colours of indicator 1 AO1
until there is a (permanent) 4.4.2.5
colour change RPA 2

measure / record the volume (of allow take the final (and initial) 1
citric acid) added burette reading

any one from: 1

• swirl
• use a white tile
• add the citric acid dropwise allow add the citric acid slowly
(near the end-point) (near the end-point)
• repeat and calculate a mean

09.6 any two from: 2 AO1

4.4.2.5
• can add (the citric acid) in allow can add (the citric acid) RPA 2
small increments drop by drop
allow can add (the citric acid)
slowly

• can measure variable volumes allow has a scale

• more accurate than a

measuring cylinder

29
 MARK SCHEME – GCSE CHEMISTRY – 8462/1H – JUNE 2020

Question 9 continued

AO /
Question Answers Extra information Mark
Spec. Ref.

09.7 (moles citric acid = AO2

13.3 4.3.4
× 0.0500 )
1000 1 4.4.2.5
= 0.000665 RPA 2

(moles NaOH = 3 × 0.000665 ) allow correct use of an 1

= 0.001995 incorrectly calculated number of
moles of citric acid

1000
(conc = × 0.001995)
25 1
= 0.0798 (mol/dm3) allow 0.08 or 0.080 (mol/dm ) 3

allow correct use of an

incorrectly calculated number of
moles of NaOH

alternative approach:

25.0 × conc NaOH 3 13.3 ×0.0500 1

= (1) allow =
13.3 × 0.0500 1 25.0 ×conc NaOH 3

13.3 × 0.0500
(conc NaOH =) 3 ×
25.0
(1)

= 0.0798 (mol/dm3) (1) allow 0.08 or 0.080 (mol/dm3)

Total 18

30