Notesale: Turn your study into money

Document Preview

Extracts from the notes are below, to see the PDF you'll receive please use the links above

---

Edexcel a level
chemistry question
paper 2 june 2024 +
mark scheme

Please check the examination details below before entering your candidate information
Candidate surname

Centre Number

Other names

Candidate Number

Pearson Edexcel Level 3 GCE

Tuesday 18 June 2024
Morning (Time: 1 hour 45 minutes)

Chemistry

Paper
reference

9CH0/02
 

Advanced

PAPER 2: Advanced Organic and Physical Chemistry

You must have:
Scientific calculator, Data Booklet, ruler

Total Marks

Instructions

black ink or ball‑point pen
...

• IfFillpencil
in
the
boxes at the top of this page with your name,
• centre number
and candidate number
...

• Answer
the questions in the spaces provided
• Answer
– there may be more space than you need
...

• The
marks for each question are shown in brackets
• The
– use this as a guide as to how much time to spend on each question
...

A Periodic Table is printed on the back cover of this paper
...

• Read
all your working in calculations and include units where appropriate
...


P76896A

©2024 Pearson Education Ltd
...

(a) Equal amounts of four bromoalkanes were added to separate test tubes
containing 2 cm3 of a silver nitrate solution
...






Which bromoalkane would be the first to form a precipitate?
A
1‑bromobutane

(1)

B 2‑bromobutane
C 1‑bromo‑2‑methylpropane
D
2‑bromo‑2‑methylpropane
(b) Which pair of reactants will form an N‑substituted amide?



(1)

A
CH3COCl and NH3
B CH3CH2OH and NH3
C CH3COCl and CH3NH2
D
CH3CH2OH and CH3NH2

2

*P76896A0232*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

Some questions must be answered with a cross in a box
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

Answer ALL questions
...

2NH3 + CH3CH2Br → NH4Br + CH3CH2NH2



(i) Explain, by referring to the reaction mechanism, the roles of ammonia in the
formation of each of the products of this reaction
...



...



...



...




(ii) What conditions are needed for this reaction?

Method of heating



Solvent

A heat in a sealed tube

ethanol

B

ethanol

heat under reflux

C heat in a sealed tube

water

D

water

heat under reflux

(1)

*P76896A0332*

3

Turn over

(d) The halogenoalkane, 1‑bromobutane, can be formed by the reaction of
butan‑1‑ol with sodium bromide and sulfuric acid
...

Give your answer to one decimal place
...
0 C = 12
...
0 Na = 23
...
1 Br = 79
...



A Grignard reagent is formed by reacting bromoethane with magnesium
under reflux
...


(1)


...




(c) In their reactions, the Grignard reagent is best described as
A
a carbocation

(1)

B
an electrophile
C
a nucleophile
D
a radical


(d) Grignard reagents must be kept dry
...

Justify your answer by considering the polarity of both CH3CH2MgBr and water
...



...



...




*P76896A0532*

5

Turn over

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(1)

A
CO2
B HCHO
C CH3CHO
D
CH3COCH3
(Total for Question 2 = 6 marks)

6

*P76896A0632*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(e) Which compound will form a tertiary alcohol when it reacts with a
Grignard reagent, followed by acid hydrolysis?



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

3 This question is about hydrogen peroxide, H2O2
...




(b) Hydrogen peroxide decomposes to form water and oxygen
...


(3)


...



...



...



...



...
100

0
...
90 × 10–7

2

0
...
0500

3
...
200

0
...
56 × 10–6

(i) Deduce the order of reaction with respect to hydrogen peroxide and to
iodide ions
...

Order with respect to iodide ions
...


(iii) Calculate the rate constant, k, using data from Experiment 3
...


8

*P76896A0832*

(1)

(2)



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

The kinetics of this reaction were investigated using different concentrations of
hydrogen peroxide and iodide ions
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(c) The decomposition of hydrogen peroxide is catalysed by iodide ions, I–(aq)
...

The presence of a detergent results in a rapid eruption of foam as the oxygen gas
is released
...


(1)


...



...


Explain what causes this colour, which is not caused by the detergent
...



...



...




*P76896A0932*

9

Turn over

0
...
0032

1/T / K–1
0
...

A graph of ln k against 1/temperature (1/T) was plotted
...
0036

–7

–8
ln k
–9

–10

–11


10

(i) Determine the gradient of the graph
...
You must show your working on the graph
...

ln k = –

Ea 1
× + constant
R T

[Gas constant (R) = 8
...

k = Ae–Ea /RT

The constant A is often called the collision factor as it is linked to the orientation
of the particles colliding in a reaction
...

Calculate a value for A at 370 K, for the catalysed decomposition of
hydrogen peroxide with an activation energy, Ea , of 5
...
60 × 10–3
...


(2)

(Total for Question 3 = 18 marks)



*P76896A01132*

11

Turn over

Your answer should consider
•

the different ways of dealing with waste polymers

•

how chemists can limit the problems caused by the disposal of polymers
...



...



...



...



...



...



...



...



...



...



...


12

*P76896A01232*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

* 4 Discuss the role society, and chemists in particular, can play in order to contribute to
a more sustainable use of polymers
...



...



...



...



...



...



...



...



...



...



...



...



...


(Total for Question 4 = 6 marks)



*P76896A01332*

13

Turn over

(a) The hydrocarbon cyclopentane is present in some fuels and is used in the
manufacture of insulation for freezers
...

Pt

+ H2

heat
2‑methylbutane

cyclopentane

Name the type of reaction that takes place in this synthesis
...




(b) The energy density of a fuel is defined as the energy released per dm3 of the
liquid fuel burned
...
0 g releases 1
...

Calculate the energy density of cyclopentane
...

[Density of cyclopentane = 0
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



(c) Under appropriate conditions, cyclopentane reacts with bromine to
form bromocyclopentane
...


(1)


...

Curly arrows are not required
...

+ Br
...


+ HBr

2
...




*P76896A01532*

(1)

15

Turn over

(d) Bromocyclopentane forms cyclopentene when heated under reflux with a
concentrated solution of potassium hydroxide in ethanol
...


(2)


...



...



...




(ii) Give the name of the reaction shown in the equation
...


(iii) Predict the mechanism for the reaction by adding two curly arrows
...


(2)


...



...



...

The low resolution 1H NMR spectrum of Q has three peaks
...


(1)


...




18

(ii) Deduce the structure of Q
...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



(d) Two cyclic alcohols have the structures shown
...


(2)


...



...



...


(Total for Question 6 = 7 marks)



*P76896A01932*

19

Turn over

Cl

chloroprene


(a) What is the IUPAC name of chloroprene?

(1)

A
3‑chlorobuta‑1,3‑diene
B 2‑chlorobuta‑2,4‑diene
C 3‑chlorobuta‑2,4‑diene
D
2‑chlorobuta‑1,3‑diene


(b) Calculate the volume, in cm3, occupied by 10
...
0 °C and 205 kPa
...




20

[Gas constant (R) = 8
...

It is formed by the polymerisation of chloroprene
...


+ Cl2

Cl

Step 1

Step 2

Cl
+ HCl

Compound A
Cl


(i) Explain how chlorine, Cl2 , can act as an electrophile in Step 1 even though a
chlorine molecule is symmetrical
...


(2)


...



...



...

Include curly arrows, and any relevant lone pairs and dipoles
...


(1)


...


A polyester may be made by the reaction of benzene‑1,4‑dicarboxylic acid with
ethane‑1,2‑diol
...

A detailed description of the forces involved is not required
...



...



...


22

*P76896A02232*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

H Cl

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(iii) Chloroprene polymerises to form neoprene as shown
...


Calculate the number of polymer molecules in 4
...

[Avogadro constant (L) = 6
...
40 mol dm–3 sodium hydroxide solution
onto a polyester laboratory coat
...

What type of reaction occurred?

(1)

A
dehydration
B
hydrolysis
C
neutralisation
D
redox
(Total for Question 7 = 17 marks)



*P76896A02332*

23

Turn over

The structures of two amino acids are shown
...




(i) State what is meant by the term ‘chiral carbon atom’
...



...






(ii) Draw diagrams of the two stereoisomers of alanine, showing their
three‑dimensional shape
...


24

*P76896A02432*

(2)

(2)



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

8 This question is about amino acids and related compounds
...


What is the formula of this zwitterion?

(1)

CH2OH
+

A
H3N C CO2–
H
CH2OH
+

B
H3N C COOH
H
CH2OH
C
H2N C CO2–
H
CH2O–
+

D
H3N C COOH
H



*P76896A02532*

25

Turn over

H
C

H3C

O
C

O

H
C
HN

O

H

C

O

H
C
CH3

O

C

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

H

CH3
Compound X
C2H5O–Na+

Step 1

H
C

O

O

O
C

:


 H


 H3C







C

HN

H

C

O

C
CH3

O

C
CH3

H

H
C

O

O
C

CH3
C
HN

+ C2H5OH + Na+

CH3Br

Step 2

H3C

H

–

O

H

C
C

O
O

H
+ Br–

C
CH3

CH3
Compound Y
Step 3
CH3
H2N C COOH + CH3COOH + 2CH3CH2OH + CO2
H
26

*P76896A02632*



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

(d) Alanine can be synthesised as shown
...


Write the equation for this reaction
...




(ii) Name the two functional groups present in Compound Y
...



...


(2)


...


(iv) Calculate the mass of Compound X required to make 15
...




*P76896A02732*

(3)

27

Turn over

(e) A mixture of amino acids can be separated using a technique called
paper electrophoresis
...


positive electrode

strip of filter paper
soaked in a buffer
solution of pH = 9

concentrated spot of
amino acid mixture
containing amino acid Z

negative electrode

Amino acid Z has the structure shown
...


(2)


...



...



...


DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

BLANK PAGE



*P76896A02932*

29



*P76896A03032*

30

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

BLANK PAGE

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA

BLANK PAGE



*P76896A03132*

31

DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA DO NOT WRITE IN THIS AREA



*P76896A03232*

32

Mark Scheme (Results)
Summer 2024
Pearson Edexcel GCE
In Chemistry (9CH0)
Paper 02: Advanced Organic and Physical
Chemistry

Edexcel and BTEC Qualifications
Edexcel and BTEC qualifications are awarded by Pearson, the UK’s largest
awarding body
...
For further
information visit our qualifications websites at www
...
com or
www
...
co
...
Alternatively, you can get in touch with us using the details
on our contact us page at www
...
com/contactus
...
Our aim is to
help everyone progress in their lives through education
...

We’ve been involved in education for over 150 years, and by working across
70 countries, in 100 languages, we have built an international reputation for
our commitment to high standards and raising achievement through
innovation in education
...
pearson
...
Examiners must
mark the first candidate in exactly the same way as they mark the
last
...
Candidates must be
rewarded for what they have shown they can do rather than penalised
for omissions
...


•

There is no ceiling on achievement
...


•

All the marks on the mark scheme are designed to be awarded
...
e
...

Examiners should also be
prepared to award zero marks if the candidate’s response is not
worthy of credit according to the mark scheme
...


•

When examiners are in doubt regarding the application of the mark
scheme to a candidate’s response, the team leader must be consulted
...


Using the Mark scheme
Examiners should look for qualities to reward rather than faults to penalise
...
Examiners should therefore read carefully and consider
every response: even if it is not what is expected it may be worthy of credit
...

/ means that the responses are alternatives and either answer should receive full
credit
...

Phrases/words in bold indicate that the meaning of the phrase or the actual word is
essential to the answer
...

Candidates must make their meaning clear to the examiner to gain the Mark
...
Do not give credit for correct words/phrases which
are put together in a meaningless manner
...

Quality of Written Communication
Questions which involve the writing of continuous prose will expect candidates to:
• write legibly, with accurate use of spelling, grammar and punctuation in order to
make the meaning clear
• select and use a form and style of writing appropriate to purpose and to complex
subject matter
• organise information clearly and coherently, using specialist vocabulary when
appropriate
...

Questions where QWC is likely to be particularly important are indicated (QWC) in the
Mark scheme, but this does not preclude others
...
g
...
9 + 98
...
9 + 120
...
9 ÷ 275) × 100 = 49
...
8 (%)
Correct answer with no working scores 2
TE from M1 to M2
Incorrect rounding for final answer does not score M2
(Total for Question 1 = 8 marks)

Question
Number
2(a)

Answer

Mark

The only correct answer is B (ether)

(1)

A is not correct because cyclohexane is not a good solvent for Grignard reagents as it is not polar
C is not correct because ethyl ethanoate would react with Grignard reagents
D is not correct because hexane is not a good solvent for Grignard reagents as it is not polar
Question
Number
2(b)

Answer

Additional Guidance

An answer that makes reference to the following point:
•

Mark
(1)

to increase the length of a carbon chain (in a molecule)
/ extend the carbon chain

Accept to form a (new) carbon- carbon (single)
bond
Allow to increase the number of carbon(s)
(atoms) (in the starting material) /
Ignore to increase chain length / add to the
carbon chain
Ignore adding alkyl groups

Question
Number
2(c)

Answer
The only correct answer is C (a nucleophile)
A is not correct because the reactive carbon has a partial negative charge
B is not correct because the reactive carbon has a partial negative charge
D is not correct because the reactive carbon has a partial negative charge

Mark
(1)

Question
Number
2(d)

Question
Number
2(e)

Answer

Additional Guidance

An answer that makes reference to the following points:

Mark
(2)

•

ethane

(1)

Accept CH3CH3 / C2H6

•

(partially) negative carbon (in Grignard reagents) is
attracted to / reacts with the (partially) positive
hydrogen (in water)

(1)

Allow use of symbols e
...
δ− C, δ+ H
Allow use of full negative charges on C and H

Answer
The only correct answer is D (CH3COCH3)

Mark
(1)

A is not correct because CO2 would form a carboxylic acid with a Grignard reagent
B is not correct because HCHO would form a primary alcohol with a Grignard reagent
C is not correct because CH3CHO would form a secondary alcohol with a Grignard reagent
(Total for Question 2 = 6 marks)

Question
Number
3(a)

Answer

Additional Guidance

Mark
(1)

Ignore omission of circles
Ignore line to show covalent bonds
Allow reversal of dots and crosses
Allow all dots or all crosses
Question
Number
3(b)

Answer

Additional Guidance

An explanation that makes reference to the following points:

Oxidation numbers may be shown above /
below species in equation

•

oxidation number of oxygen has changed from –1 (in
H2O2)

(1)

•

to –2 in water, so reduced

(1)

•

and 0 in (elemental) oxygen, so is oxidised

(1)

Allow Roman numerals to show oxidation
numbers

Allow 1 rescue mark for correct oxidation
numbers of oxygen in both products if references
to oxidation and reduction incorrect or omitted
or not linked to a specific reaction in M2 and M3
Allow 1 rescue mark for correct oxidation
numbers and references to oxidation and
reduction if products omitted in M2 and M3

Mark
(3)

Question
Number
3(c)(i)

Question
Number
3(c)(ii)

Answer

Additional Guidance

An answer that makes reference to the following points:

(2)

•

(order with respect to hydrogen peroxide =) 1 / first

(1)

•

(order with respect to iodide ions =) 1 / first

(1)

Answer
An answer that makes reference to the following point:
•

rate / r = k[H2O2][I–]

Mark

Additional Guidance
Rate equation must be consistent on orders from (i)
Allow use of correct names
Allow TE from 3(c)(i)
Do not award round brackets
Do not award omission of rate / r

Mark
(1)

Question
Number
3(c)(iii)

Answer

Additional Guidance
Example of calculation
Calculation must be consistent on rate equation from
(ii)

•

calculation of k

(1) k = rate ÷ [H2O2][I–]
3
...
200 × 0
...
78 × 10–4

•

units of k

(1) dm3 mol–1 s–1
Allow dm3/mol/s
Allow dm3 mol– s–
Allow units in any order
Ignore SF except 1 SF
Allow TE from incorrect rate equation in 3(c)(ii)
Allow calculation based on data from experiments 1
or 2
NOTE – with TE on incorrect order, calculation and
units require checking as different experiments give
different values

Mark
(2)

Question
Number
3(d)(i)

Answer
An answer that makes reference to the following points:
•

Question
Number
3(d)(ii)

Additional Guidance

Mark
(1)

Ignore ‘a splint that has (just) been blown out
relights’

put glowing splint (into bubbles of gas / presence of
gas)
and
splint relights

Do not award ‘relights a burnt splint’
Do not award squeaky pop

Answer

Additional Guidance

An explanation that makes reference to the following points:

Mark
(2)

•

(colour caused by aqueous solution of) iodine

(1)

Accept (colour caused by) aqueous (solution of) I3–
Ignore iodide ions are yellow in solution
Do not award iodine ions

•

(formed as excess hydrogen) peroxide oxidises iodide
(ions) / converts iodide (ions) / reacts with iodide
(ions)

(1)

Allow oxygen oxidises / converts / reacts with the
iodide (ions) / iodide reduces (hydrogen) peroxide
Allow correct equation
2H+ + H2O2 + 2I– → I2 + 2H2O
Ignore incomplete equations (as considered part of
the working out process)

Question
Number
3(e)(i)

Answer

Additional Guidance
Example of calculation

•

triangle or similar shown on graph to indicate
changes in x and y

(1)

Allow circling of points / marking of points on line
For example
–11– - 6 = –5
0
...
003038 = 0
...
00055 = – 9090
...
9 × 8
...
545 (kJ mol–1)
Allow (+) 75545 J mol–1
Ignore SF except 1 SF
Allow TE from (e)(i)
Do not award negative activation energies
...
31 × 370) / 8
...
60 × 10–3 ÷ 8
...
9713 × 104
Ignore SF
Ignore units
TE from M1 to M2
Correct answer with no working scores 2
Note – use of rounded values of e−Ea /RT is acceptable
and final answer may need checking as it will make a
difference to the numerical value
M1 can be subsumed in M2
(Total for Question 3 = 18 marks)

Question
Number
*4

Answer
This question assesses the student’s ability to show a coherent and
logically structured answer with linkages and fully sustained
reasoning
...

The following table shows how the marks should be awarded for
indicative content
...


Answer shows a coherent
logical structure with linkages
and fully sustained lines of
reasoning demonstrated
throughout
Answer is partially structured
with some linkages and lines
of reasoning
Answer has no linkages
between points and is
unstructured

Number of marks awarded for
structure of answer and
sustained lines of reasoning
2

1
0

Additional Guidance

Mark

Guidance on how the mark scheme should be applied
...

For example, a response with five indicative marking
points that is partially structured with some linkages
and lines of reasoning scores 4 marks (3 marks for
indicative content and 1 mark for partial structure and
some linkages and lines of reasoning)
...

In general it would be expected that 5 or 6 indicative
points would get 2 reasoning marks, and 3 or 4
indicative points would get 1 mark for reasoning, and
0, 1 or 2 indicative points would score zero marks for
reasoning
...
If no reasoning mark(s) awarded do not
deduct mark(s)
...


Indicative content
Treatment of waste polymers
IP1 (waste) polymers can be (sorted and) recycled

Allow re-use / repurpose (objects made from)
polymers

IP2 (waste) polymers can be incinerated to release energy /
generate electricity

Allow polymers can be incinerated to release heat
/ used as a fuel

IP3 (waste) polymers can be cracked / thermally
decomposed (to (re)form monomers)

Allow polymers can be used as a feedstock/raw
material for cracking
Allow polymers can converted into smaller / more
useful molecules (to be used as a feedstock)

Limiting problems caused by disposal
IP4 (chemists) develop / invent (new) biodegradable
polymers

Allow use /develop / invent (new) polymers that
decompose
Ignore use of alternative non-synthetic materials
Ignore biofuels

IP5 (chemists can help develop techniques to) minimise
emission of harmful / toxic / acidic gases from
incineration (of waste polymers)

Allow minimise emissions of named pollutants
from incineration e
...
HCl / SO2 / NOx / CO2 / CO
/ dioxins
Ignore comments on greenhouse gases / global
warming

IP6 by neutralising HCl / SO2 / NOx

Allow by carbon capture of CO2
Allow by ensuring complete combustion to
minimise CO / by converting CO to CO2
(Total for Question 4 = 6 marks)

Question
Number
5(a)

Answer
An answer that makes reference to the following point:
•

Question
Number
5(b)

Question
Number
5(c)(i)

Additional Guidance

reforming/reformation

Answer

(1)
Allow dehydrogenation / cyclisation
Ignore oxidation / catalytic
Do not award cracking / dehydration
Additional Guidance
Example of calculation

•

calculate volume of cyclopentane

(1) Volume = 30
...
751 / 39
...
41 ÷ (39
...
297 MJ dm–3

Answer

UV (light) / ultraviolet (light)

Mark
(2)

Ignore SF except 1 SF
Allow TE from M1
Allow 3
...
5297 × 107 J dm–3
3
...
g
...
g
...
5

•

calculation of amount of chloroprene in mol

(1) 10
...
5 / = 0
...
11299 × 8
...
6169 × 10–3 (m3)
M4 may be subsumed in M5
Ignore units in M4

•

conversion to cm3 and rounding to 2 or 3 SF

(1) 1600 / 1620 (cm3)
1620 with no working scores 5
Comments
Allow use of correctly rounded values carried forward
Take care with awarding 5 for 1600, as it may be the result
of an incorrect value from M4, correctly rounded

Mark
(5)

Question
Number
7(c)(i)

Answer

Additional Guidance

An explanation that makes reference to the following points:
•

chlorine (molecule) moves close to (electron rich)
double bond / pi bond

(2)
(1)
(1)

M1 via diagram e
...
25 × 10–3 ÷ 8400 = 5
...
0595 × 10–7 × 6
...
0458 × 1017 (molecules)
Ignore SF
Allow TE from M1
If incorrect units given in M1 and M2, penalise only once
Correct answer with or without working scores 2 marks

Mark
(2)

Question
Number
7(d)(iii)

Answer
The only correct answer is B (hydrolysis)

Mark
(1)

A is not correct as the reaction as dehydration is the removal of water
C is not correct as the reaction as neutralisation is a reaction between an acid and a base
D is not correct as the reaction as redox is oxidation and reduction
(Total for Question 7 = 17 marks)

Question
Number
8(a)(i)

Answer

Additional Guidance

An answer that makes reference to the following point:
•

a carbon atom with four different atoms / groups (of
atoms) attached

Mark
(1)

Allow resulting molecule has non-superimposable
mirror images
Allow a carbon atom with four different functional
groups attached
Ignore a carbon atom with four different species
attached
Do not award ‘molecules’ for atoms / groups

Question
Number
8(a)(ii)

Answer
•

COOH

HOOC

Additional Guidance

Mark

Allow 1 mark for 2 tetrahedral mirror images
shown with only lines and no wedges / dashed lines
Allow 1 mark for 2 tetrahedral mirror images
shown with two similar wedges on each structure

(2)

Accept dashed line for dashed wedges
Ignore connectivity

Question
Number
8(b)

Answer
•

Additional Guidance

Mark

Allow 1 mark for 2 correct structures shown as structural
or displayed formulae

(2)

Ignore displayed NH2 , NH, or OH groups
H2N

(1)

Penalise missing hydrogen atoms on amide group once
only
Penalise NH group shown as part of chain once only

•
H2N

(1)

Allow 1 if both dipeptides shown as correct polymer
repeat units

and

Question
Number
8(c)

Answer
The only correct answer is A

B is not correct because the CO2H group has not lost a proton
C is not correct because the NH2 group has not gained a proton
D is not correct because the CH2OH group has lost a proton

Mark
(1)

Question
Number
8(d)(i)

Answer
•

Additional Guidance
Examples
C2H5OH + Na → C2H5ONa + ½H2
C2H5OH + Na → C2H5O−Na+ + ½H2
C2H6O + Na → C2H5ONa + ½H2
C2H6O + Na → C2H5O−Na+ + ½H2

balanced equation

Mark
(1)

Allow multiples
Allow displayed / skeletal / molecular formulae
Ignore state symbols even if incorrect
Do not award C2H5OH + Na → C2H5Oδ−Naδ+ + ½H2

Question
Number
8(d)(ii)

Answer

Additional Guidance

An answer that makes reference to the following point:

Mark
(2)

•

ester

(1)

If 3 answers given and 2 are correct, award 1 mark

•

(N-substituted) amide

(1)

If 4 or more answers given and 2 are correct award 0
marks
Ignore structures, even if incorrect

Question
Number
8(d)(iii)

Answer

Additional Guidance

An answer that makes reference to the following points:

Ignore references to concentrated / dilute

•

hydrochloric acid / HCl(aq)

(1)

•

(heat under) reflux

(1)

Allow HCl
Allow correct name or formulae of any strong acid e
...

HNO3, H2SO4,
Allow phosphoric acid / H3PO4
Allow NaOH followed by any identified strong acid
Ignore H+ / H3O+ / catalyst
Mark independently

Mark
(2)

Question
Number
8(d)(iv)

Answer

Additional Guidance
Example of calculation

•

calculation of moles of alanine

(1)

15
...
0 = 0
...
16854 × (100 ÷ 55) = 0
...
30644 × 217 = 66
...
5 g

OR
•

scale mass of alanine to 100%

(1)

15
...
273 (g)

•

calculation of moles of alanine

(1)

27
...
0 = 0
...
30644 × 217 = 66
...
5 g

(1)

15
...
0 = 0
...
16854 × 217 = 36
...
573 × (100 ÷ 55) = 66
...
5 g

OR
•

calculation of moles of alanine

•

calculate mass of X

•

scale to 100 %

Correct answer no working scores 3
Ignore SF except 1 SF
Allow TE throughout
If no mark scored allow 1 mark for 2 correct Mr
values, 89 and 217

Mark
(3)

Question
Number
8(e)

Answer

Additional Guidance

An explanation that makes reference to the following points:

•

would move towards the positive electrode / to the
left
and
as it will form a negative ion

•

(as basic pH means) the acid groups will both lose a
proton / has two COO– groups

Note
The negative charge on the ion and loss of both
hydrogen ions from the COOH groups can both be
awarded from a correct diagram of the ion
(1)

Do not award zwitterion

(1)

Allow the acid groups will both lose a hydrogen
(ion)
M2 can be awarded from diagram / amended
structure in question

Mark
(2)

(Total for Question 8 = 16 marks)
TOTAL FOR PAPER = 90 MARKS

Pearson Education Limited

---