A-Level EDEXCEL 2025 Chemistry PAPER 2 Mark Scheme
Mark Scheme (Results)
Summer 2025
Pearson Edexcel GCE A Level In Chemistry (9CH0)
Paper 02: Advanced Organic and Physical Chemistry
Using the Mark Scheme
Examiners should look for qualities to reward rather than faults to penalise. This does NOT mean giving credit for incorrect or inadequate
answers, but it does mean allowing candidates to be rewarded for answers showing correct application of principles and knowledge.
Examiners should therefore read carefully and consider every response: even if it is not what is expected it may be worthy of credit.
The mark scheme gives examiners:
an idea of the types of response expected
how individual marks are to be awarded
the total mark for each question
examples of responses that should NOT receive credit.
/ means that the responses are alternatives and either answer should receive full credit.
( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer.
Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.
,ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part
of the same question.
Candidates must make their meaning clear to the examiner to gain the mark. Make sure that the answer makes sense. Do not give credit for
correct words/phrases which are put together in a meaningless manner. Answers must be in the correct context.
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. Full
marks will be awarded if the candidate has demonstrated the above abilities.
Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.
,Question
Answer Mark
Number
1(a) The only correct answer is C (CH2(OH)COOH) (1)
A is not correct because propanoic acid has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
B is not correct because oxoethanoic acid has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
D is not correct because methyl ethanoate has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
Question
Answer Mark
Number
1(b) The only correct answer is B (29) (1)
+
A is not correct because both propanal and propanone could produce a CH3 fragment with m/z = 15
C is not correct because propanal could produce the fragment [CH2CHO+]and propanone could produce the
fragment [CH3CO+] which both have m/z = 43
D is not correct because both propanal and propanone have this (M+1)+ peak which is not a fragment ion
(Total for Question 1 = 2 marks)
, Question
Answer Mark
Number
2(a) The only correct answer is A ((CH3)2CHCH2C(CH3)3) (1)
B is not correct because this is not the most branched isomer as it only has two branches
C is not correct because this is not the most branched isomer as it only has two branches
D is not correct because this unbranched isomer will have the highest boiling temperature
Question
Number Answer Additional Guidance Mark
2(b) An explanation that makes reference to the following points: (2)
(only) pentan-1-ol has hydrogen bonds (1) Can be shown on a diagram for M1
Do not award reference to covalent bonding
(Intermolecular forces in pentan-1-ol) are stronger
and Accept answers referring to higher boiling
require more energy to break (hence the lower (1) temperature instead of lower volatility of pentan-
volatility) 1-ol
Allow reverse argument: hexane only has London
forces which are weaker than Hydrogen bonds and
so require less energy to break scores 2
(Allow VdW/dispersion forces/instantaneous
induced dipoles)
Ignore references to permanent dipole-dipole
forces
Mark Scheme (Results)
Summer 2025
Pearson Edexcel GCE A Level In Chemistry (9CH0)
Paper 02: Advanced Organic and Physical Chemistry
Using the Mark Scheme
Examiners should look for qualities to reward rather than faults to penalise. This does NOT mean giving credit for incorrect or inadequate
answers, but it does mean allowing candidates to be rewarded for answers showing correct application of principles and knowledge.
Examiners should therefore read carefully and consider every response: even if it is not what is expected it may be worthy of credit.
The mark scheme gives examiners:
an idea of the types of response expected
how individual marks are to be awarded
the total mark for each question
examples of responses that should NOT receive credit.
/ means that the responses are alternatives and either answer should receive full credit.
( ) means that a phrase/word is not essential for the award of the mark, but helps the examiner to get the sense of the expected answer.
Phrases/words in bold indicate that the meaning of the phrase or the actual word is essential to the answer.
,ecf/TE/cq (error carried forward) means that a wrong answer given in an earlier part of a question is used correctly in answer to a later part
of the same question.
Candidates must make their meaning clear to the examiner to gain the mark. Make sure that the answer makes sense. Do not give credit for
correct words/phrases which are put together in a meaningless manner. Answers must be in the correct context.
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. Full
marks will be awarded if the candidate has demonstrated the above abilities.
Questions where QWC is likely to be particularly important are indicated (QWC) in the mark scheme, but this does not preclude others.
,Question
Answer Mark
Number
1(a) The only correct answer is C (CH2(OH)COOH) (1)
A is not correct because propanoic acid has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
B is not correct because oxoethanoic acid has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
D is not correct because methyl ethanoate has a relative molecular mass of 74 and so would have a molecular ion
peak with m/z = 74
Question
Answer Mark
Number
1(b) The only correct answer is B (29) (1)
+
A is not correct because both propanal and propanone could produce a CH3 fragment with m/z = 15
C is not correct because propanal could produce the fragment [CH2CHO+]and propanone could produce the
fragment [CH3CO+] which both have m/z = 43
D is not correct because both propanal and propanone have this (M+1)+ peak which is not a fragment ion
(Total for Question 1 = 2 marks)
, Question
Answer Mark
Number
2(a) The only correct answer is A ((CH3)2CHCH2C(CH3)3) (1)
B is not correct because this is not the most branched isomer as it only has two branches
C is not correct because this is not the most branched isomer as it only has two branches
D is not correct because this unbranched isomer will have the highest boiling temperature
Question
Number Answer Additional Guidance Mark
2(b) An explanation that makes reference to the following points: (2)
(only) pentan-1-ol has hydrogen bonds (1) Can be shown on a diagram for M1
Do not award reference to covalent bonding
(Intermolecular forces in pentan-1-ol) are stronger
and Accept answers referring to higher boiling
require more energy to break (hence the lower (1) temperature instead of lower volatility of pentan-
volatility) 1-ol
Allow reverse argument: hexane only has London
forces which are weaker than Hydrogen bonds and
so require less energy to break scores 2
(Allow VdW/dispersion forces/instantaneous
induced dipoles)
Ignore references to permanent dipole-dipole
forces
