GCSE

CHEMISTRY
8462/2H
Paper 2 Higher Tier
Mark scheme
June 2019
Version: 1.0 Final

*196G8462/2H/MS*
 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

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 © 2019 AQA and its licensors. All rights reserved.

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.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Level of response marking instructions

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 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. With
practice and familiarity you will find that for better answers you will be able to quickly skip through the
lower levels of the mark scheme.

When assigning a level you should look at the overall quality of the answer and not look to pick holes in
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 and then use the variability of the response to help decide the mark within
the level, ie if the response is predominantly level 3 with a small amount of level 4 material it would be
placed in level 3 but be awarded a mark near the top of the level because of the level 4 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.

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

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

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 – 8462/2H – JUNE 2019

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 – 8462/2H – JUNE 2019

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.

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.

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

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 – 8462/2H – JUNE 2019

Question 1

AO /
Question Answers Extra information Mark
Spec. Ref.

a temperature between 400 (°C) allow a temperature range 1 AO3

01.1 and 500 (°C) inclusive entirely within 400 (°C) and 500 4.7.1.2
(°C) inclusive

ignore quoted values for boiling AO2

points 4.7.1.2

ignore references to melting

points

ignore references to
intermolecular forces or chain
length

allow temperature of
vaporisation / condensation for
01.2
boiling points throughout
(diesel oil has a) lower boiling 1
point / range than heavy fuel oil

(but diesel oil has a) higher 1

boiling point / range than
kerosene

allow the boiling range (of diesel

oil) is between those of heavy
fuel oil and kerosene for 2
marks.

ignore references to cost AO2

4.7.1.3
any two from: 2

• (too) viscous allow references to difficulty of

flow
01.3
• not (very) flammable allow references to difficulty of
ignition / burning
do not accept bitumen takes
more energy to burn

• boiling point (too) high allow not (very) volatile

C6H14 1 AO2
01.4
4.7.1.1

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

ignore references to pressure AO1

4.7.1.4
high temperature allow a quoted temperature 1
above 320 °C

ignore hot / heat

any one from: 1

01.5
• steam
• catalyst ignore name of catalyst
allow alumina
allow aluminium oxide
allow porous pot
allow zeolite

allow converse argument for AO1

larger molecules 4.7.1.4

greater demand (for smaller 1

molecules)

any one from: 1

01.6
(because smaller molecules are)
• more useful
• better fuels
• used to make alkenes
• used to make polymers allow a named polymer

ignore plastics

C3H6 1 AO2
01.7 4.1.1.1
4.7.1.4

Total 11

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 2

AO/
Question Answers Mark
Spec. Ref

AO1
Level 3: The design/plan would lead to the production of a valid 4.8.2.3
02.1 5–6
outcome. All key steps are identified and logically sequenced. 4.8.3.1
4.8.3.3

Level 2: The design/plan would not necessarily lead to a valid

outcome. Most steps are identified, but the plan is not fully logically 3–4
sequenced.

Level 1: The design/plan would not lead to a valid outcome. Some

1–2
relevant steps are identified, but links are not made clear.

No relevant content 0

Indicative content

lithium:
• crush tablets or dissolve tablet (in water or acid)
• clean wire
• place on wire
• place in (roaring / blue / non-luminous) flame
• observe flame colour
• crimson flame

carbonate:
• add hydrochloric acid
• effervescence / fizzing
• bubble gas through limewater
• limewater becomes cloudy

AO1
02.2 formulation(s) 1
4.8.1.2

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

an answer of 58.3333333 (%) AO2

correctly rounded to at least 2 4.8.1.2
significant figures scores 3
marks

1.20 g = 1200 mg 1
or
700 mg = 0.700 g

02.3

700 0.700 allow correct use of incorrectly 1

× 100 or × 100
1200 1.20 or not converted values from
step 1

= 58.3 (%) allow 58.3333333 (%) correctly 1

rounded to at least 2 significant
figures

Total 10

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 3

AO /
Question Answers Extra information Mark
Spec. Ref.

(aq) allow aqueous / aq 1 AO1

03.1 4.2.2.1
4.2.2.2

(gas) syringe allow measuring cylinder (and 1 AO1

water trough) 4.6.1.1
03.2 allow balance

stopclock / stopwatch allow timer / clock / watch 1

all points plotted correctly allow a tolerance of ± ½ a small 2 AO2

square 4.6.1.1

allow at least 3 points plotted

03.3 correctly for 1 mark.

line of best fit allow correctly drawn line of best 1

fit for incorrectly plotted points

(rate) decreases allow slows down 1 AO3

4.6.1.1

(rate decreases) more slowly as allow (rate decreases) at a non- 1

03.4 time increases linear rate

(rate) becomes zero at 60 s allow the reaction stops at 60 s 1

allow ecf from question 03.3

more bubbles were produced in 1 AO2

the first 10 seconds 4.6.1.2
03.5
the magnesium was used up 1
more quickly

Total 11

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 4

AO /
Question Answers Extra information Mark
Spec. Ref.

Tube 1: (nail) rusts because air / 1 AO1

oxygen and water present

Tube 2: (nail) does not rust allow Tube 2: (nail) does not 1 AO1
because no water rust because only air / oxygen

Tube 3: (nail) does not rust allow Tube 3: (nail) does not 1 AO1
because no air / oxygen rust because only water

Tube 4: (nail) does not rust allow Tube 4: (nail) does not 1 AO1
because paint is a barrier (to rust because paint is a
water / air / oxygen) protective layer / coating
(against water / air / oxygen)

or AO2
04.1
allow Tube 4: (nail) does not 4.10.3.1
rust because paint protects it 4.10.3.2
from water / air / oxygen
1

Tube 5: (nail) does not rust allow Tube 5: (nail) does not
because stainless steel resistant rust because stainless steel
to corrosion does not corrode
allow Tube 5: (nail) does not
rust because stainless steel
contains nickel / chromium

If no other mark awarded allow

1 mark for correct rusting
pattern in all 5 tubes

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

allow converse AO2

4.10.3.1
magnesium is more reactive allow magnesium is more 1
(than iron) reactive (than steel)

(so magnesium) provides allow (so magnesium) corrodes / 1

04.2 sacrificial protection reacts instead of iron / steel
allow (so magnesium) corrodes /
reacts before iron / steel

ignore references to protective

layers
ignore references to magnesium
rusting

(aluminium has a coating of) 1 AO1

aluminium oxide 4.10.3.1

04.3 (so the aluminium oxide) allow (so aluminium oxide) 1

protects the metal (from further prevents water / air / oxygen
corrosion) from reaching the metal

Total 9

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 5

AO /
Question Answers Extra information Mark
Spec. Ref.

wood is renewable 1 AO3

or 4.9.2.2
(natural) gas is finite 4.10.1.1

(burning) wood produces the allow wood is carbon-neutral 1

same amount of carbon dioxide allow wood does not add to
as the trees absorbed global warming
05.1 or
(burning natural) gas increases allow (burning natural) gas adds
the amount of carbon dioxide (in to global warming
the atmosphere) allow (burning natural) gas adds
greenhouse gases (to the
atmosphere)

ignore references to energy /

cost

not enough oxygen allow not enough air 1 AO1

do not accept no oxygen / air 4.9.3.1
05.2

(so) incomplete combustion 1

2CH4(g)+3O2(g)→2CO(g)+4H2O allow correct multiples / fractions 1 AO2

05.3
(g) 4.9.3.1

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

an answer of 1250 (cm3 oxygen AO2

unreacted) scores 4 marks 4.3.5
4.7.1.3
ratio of O2 : CO2 = 5 : 3 1

(oxygen needed =
3.60 × 5
) allow correct calculation using
3 an incorrectly determined mole
= 6.0 (dm3) ratio 1

allow correct subtraction of an

(oxygen unreacted = 7.25 – 6.0) incorrectly calculated volume of
= 1.25 (dm3) oxygen 1

05.4 allow correct conversion to cm3

(oxygen unreacted = 1.25 × anywhere in response
1000)
= 1250 (cm3) 1

alternative approach for MP1

and MP2

moles CO2 = 0.15

and
moles O2 = 0.25 (1)

(0.25 x 24 =) 6.0 (dm3 oxygen

needed) (1)

Total 9

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 6

AO /
Question Answers Extra information Mark
Spec. Ref.

C=C bond in correct position 1 AO2

4.7.3.1

3× C-H and 1× C-C bond in do not accept any additional 1

correct positions bonds or atoms

ignore brackets and n before

and after displayed structural
formula

06.1
an answer of

scores 2 marks

carboxylic acid (group) allow carboxyl (group) 1 AO1

06.2
4.7.2.4

water allow H2O 1 AO1

06.3
4.7.3.2

(polyester is) thermosoftening allow (polyester is) 1 AO1

thermoplastic

ignore thermoforming AO3

4.10.3.3
06.4
(polyester has) no cross-links allow intermolecular forces are 1
weak
do not accept references to
breaking covalent bonds or
breaking chains

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

AO3
hydrocarbon 4.10.3.3

glass fibres matrix 1

monomer

polyester polypeptide 1
reinforcement
allow for 1 mark:
06.5
hydrocarbon

glass fibres matrix

monomer

polyester polypeptide

reinforcement

any two from: 2 AO3

(to make the board) 4.10.3.3
• harder
• stronger must be implied comparative
• tougher statements
06.6 • more rigid

• waterproof

Total 10

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 7

AO /
Question Answers Extra information Mark
Spec. Ref.

add sodium hydroxide (solution 1 AO1

to water sample) 4.8.3.2

07.1 white precipitate (forms) 1

dependent on correct test in
(precipitate which is) soluble in MP1 1
excess (NaOH)

add barium chloride (solution) allow barium nitrate (solution) 1 AO1

and (dilute) hydrochloric acid (to allow (dilute) nitric acid 4.8.3.5
water sample)
07.2
white precipitate (forms) dependent on addition of barium 1
chloride / nitrate (solution) in
MP1

Level 2: The design/plan would lead to the production of a valid

07.3 3–4
outcome. All key steps are identified and logically sequenced.

Level 1: The design/plan would not lead to a valid outcome. Some

1–2
relevant steps are identified, but links are not made clear.

No relevant content 0

Indicative content

• weigh (evaporating) basin / dish

• add measured volume of water
• weigh (evaporating) basin / dish and water
AO1
• heat to evaporate water
4.10.1.2
• reweigh
• repeat heating until constant mass obtained
• subtract mass of (evaporating) basin / dish from mass
• repeat and calculate a mean, discarding anomalous results
• calculate the mass in 100 cm3 water if necessary

Total 9

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 8

AO /
Question Answers Extra information Mark
Spec. Ref.

AO3
(Titan has) little / no oxygen ignore references to respiration 1 4.9.1.3

(so) photosynthesis has not allow (so) no plants / algae to 1

occurred (on Titan) produce oxygen (on Titan)
08.1
(therefore) little / no carbon 1
dioxide present (on Titan)
or
(therefore) oxygen-using
animals cannot have evolved
(on Titan)

(methane) allows short(er) allow (methane) allows uv / 1 AO1

wavelength radiation to pass ultraviolet radiation to pass 4.9.2.1
through (from the sun) through (from the sun)

(which is) re-emitted from the allow (which is) re-emitted from 1
surface as long(er) wavelength the surface as ir / infra-red
radiation radiation

08.2
(which is) absorbed (by allow (which is) trapped (by 1
methane in the atmosphere) methane in the atmosphere)

if no other mark is awarded,

allow 1 mark for methane
absorbs long(er) wavelength
radiation
or
methane absorbs ir / infra-red
radiation

(add) bromine (water) do not accept bromide 1 AO1

4.7.1.4
4.7.2.1
(changes from) orange to dependent on correct test in 1 4.7.2.2
08.3 colourless MP1
allow (changes from) brown to
colourless

ignore clear

Total 8

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 9

AO /
Question Answers Extra information Mark
Spec. Ref.

glowing splint do not accept burning splint 1 AO1

4.8.2.2

09.1
(which) relights dependent on correct test in 1
MP1
ignore with a pop

place the conical flask in a water 1 AO3

bath at constant temperature. 4.6.1.2
09.2
use a mass of 1 g manganese 1
dioxide each time.

an answer of 0.092 (cm3/s) AO2

scores 3 marks 4.6.1.1

allow an answer of 0.091666

(cm3/s) correctly rounded to at
least 2 significant figures for 2
marks

allow an answer of 0.033 (cm3/s)

for 2 marks

allow an answer of 0.033333

(cm3/s) for 1 mark

09.3
11 (cm3) and 120 (seconds) 1

11 allow a correct calculation using

(mean rate of reaction = )
120 incorrectly determined value(s) 1
= 0.09167
for difference in volume and / or
time

= 0.092 (cm3/s) allow a correctly calculated 1

answer given to 2 significant
figures from an incorrect attempt
at the rate equation

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

line starts at origin and less 1 AO2

steep than solid line
09.4
line levelling off at 40 (cm3) allow a tolerance of ± ½ a small 1 AO3
square 4.6.1.2

AO2
4.6.1.2
(because) surface area (of fine allow converse for coarse lumps 1 4.6.1.3
manganese dioxide powder)
greater
09.5
(so) more collisions (with do not accept references to 1
hydrogen peroxide molecules / changes in kinetic energy or
particles) per unit time speed (of molecules / particles)
ignore references to activation
energy.

Total 11

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

Question 10

AO /
Question Answers Extra information Mark
Spec. Ref.

an answer of 17.6470588 (%) AO2

correctly rounded to at least 2 4.3.3.2
significant figures scores 2
marks
6 1
× 100
34
10.1

= 17.6 (%) allow 17.6470588 (%) correctly 1

rounded to at least 2 significant
figures

allow converse arguments in AO2

terms of higher pressure 4.6.2.4
ignore references to rate 4.6.2.7

higher yield (of hydrogen or allow more hydrogen or more 1

carbon monoxide or product) carbon monoxide or more
product
allow equilibrium moves to the
right
allow equilibrium moves in the
forward direction
10.2
(because) fewer moles / allow (because) the reverse 1
molecules / particles on left reaction produces fewer moles /
hand side molecules / particles
or or
(because) more moles / allow (because) the forward
molecules / particles on right reaction produces more moles /
hand side molecules / particles

do not accept fewer / more

atoms

no effect (on yield of hydrogen) allow position of equilibrium 1 AO2

unaffected by pressure 4.6.2.7
10.3
ignore references to rate of
reaction

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 MARK SCHEME – GCSE CHEMISTRY – 8462/2H – JUNE 2019

an answer of 2.25 scores 3 AO2

marks 4.10.4.1

350 (°C) and 285 (atmospheres) allow a value between 62 (%) 1

= 63 (%) and 64 (%) inclusive
and
450 (°C) and 200 (atmospheres)
= 28 (%)

10.4 63 allow a correct expression using 1

28 incorrectly determined value(s)
for percentage yield

= 2.25 (times greater) allow a correct calculation using 1

incorrectly determined value(s)
for percentage yield correctly
evaluated and rounded to at
least 2 significant figures

allow converse arguments in AO1

terms of low(er) pressure 4.10.4.1
any one from: 1
• the energy costs would be ignore energy / cost unqualified
high(er)
10.5
• the equipment would need to allow the equipment would be
be strong(er) (more) expensive (to build /
maintain)
• high(er) pressures are (more) allow (more) dangerous
dangerous because (greater) risk of
explosion

higher temperatures produce a allow converse 1 AO2

lower (percentage) yield (of allow correct reference to shift in 4.6.2.6
10.6 ammonia) equilibrium 4.10.4.1

ignore references to pressure

world population has increased 1 AO3

any one from: AO1

• demand for fertiliser has allow more food needed 1 4.10.4.1
10.7 increased 4.10.4.2
• increased demand for other
specified ammonia-based
products e.g. nitric acid,
drugs, dyes, explosives

Total 12

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