000001
AQA
MARK SCHEME
A-level
CHEMISTRY
7405/3
T
Paper 3
ES
Mark scheme
June 2024
Version: 1.0 Final
B
E
TH
LL
A
Page 1 of 33
,000002
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
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
T
assessment remain constant, details will change, depending on the content of a particular examination
paper.
ES
No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
gender identity of others in their exam responses.
B
A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
E
Further copies of this mark scheme are available from aqa.org.uk
TH
LL
A
2
Page 2 of 33
,000003
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
AS and A-Level Chemistry
Mark Scheme Instructions for 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 and help to delineate what
T
is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area
in which a mark or marks may be awarded.
ES
The extra information in the ‘Comments’ column 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.
You should mark according to the contents of the mark scheme. If you are in any doubt about
applying the mark scheme to a particular response, consult your Team Leader.
At the beginning of a part of a question a reminder may be given, for example: where
diagram or at a different place on the script.
B
consequential marking needs to be considered in a calculation; or the answer may be on the
In general the right-hand side of the mark scheme is there to provide those extra details which
might confuse the main part of the mark scheme yet may be helpful in ensuring that marking is
E
straightforward and consistent.
The use of M1, M2, M3 etc in the right-hand column refers to the marking points in the order in
TH
which they appear in the mark scheme. So, M1 refers to the first marking point, M2 the second
marking point etc.
2. Emboldening
2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is
LL
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.
A
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.
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 ‘List’ 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.
3
Page 3 of 33
, 000004
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the mark
scheme) are not penalised.
For example, in a question requiring 2 answers for 2 marks:
Incorrect
Correct answers (i.e.
Mark (2) Comment
answers incorrect rather
than neutral)
1 0 1
T
They have not exceeded the maximum
1 1 1 number of responses so there is no
penalty.
ES
They have exceeded the maximum number
1 2 0 of responses so the extra incorrect
response cancels the correct one.
2 0 2
2 1 1
B
2 2 0
E
3 0 2 The maximum mark is 2
The incorrect response cancels out one of
TH
3 1 1 the two correct responses that gained
credit.
Two incorrect responses cancel out the two
3 2 0
marks gained.
3 3 0
LL
3.2 Marking procedure for calculations
Full marks should be awarded for a correct numerical answer, without any working
A
shown, unless the question states ‘Show your working’ or ‘justify your answer’. In this
case, the mark scheme will clearly indicate what is required to gain full credit.
If an answer to a calculation is incorrect and working is shown, process mark(s) can
usually be gained by correct substitution / working and this is shown in the ‘Comments’
column or by each stage of a longer calculation.
3.3 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are most likely to be restricted to calculation
questions and should be shown by the abbreviation ECF or consequential in the marking
scheme.
4
Page 4 of 33
AQA
MARK SCHEME
A-level
CHEMISTRY
7405/3
T
Paper 3
ES
Mark scheme
June 2024
Version: 1.0 Final
B
E
TH
LL
A
Page 1 of 33
,000002
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
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
T
assessment remain constant, details will change, depending on the content of a particular examination
paper.
ES
No student should be disadvantaged on the basis of their gender identity and/or how they refer to the
gender identity of others in their exam responses.
B
A consistent use of ‘they/them’ as a singular and pronouns beyond ‘she/her’ or ‘he/him’ will be credited in
exam responses in line with existing mark scheme criteria.
E
Further copies of this mark scheme are available from aqa.org.uk
TH
LL
A
2
Page 2 of 33
,000003
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
AS and A-Level Chemistry
Mark Scheme Instructions for 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 and help to delineate what
T
is acceptable or not worthy of credit or, in discursive answers, to give an overview of the area
in which a mark or marks may be awarded.
ES
The extra information in the ‘Comments’ column 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.
You should mark according to the contents of the mark scheme. If you are in any doubt about
applying the mark scheme to a particular response, consult your Team Leader.
At the beginning of a part of a question a reminder may be given, for example: where
diagram or at a different place on the script.
B
consequential marking needs to be considered in a calculation; or the answer may be on the
In general the right-hand side of the mark scheme is there to provide those extra details which
might confuse the main part of the mark scheme yet may be helpful in ensuring that marking is
E
straightforward and consistent.
The use of M1, M2, M3 etc in the right-hand column refers to the marking points in the order in
TH
which they appear in the mark scheme. So, M1 refers to the first marking point, M2 the second
marking point etc.
2. Emboldening
2.1 In a list of acceptable answers where more than one mark is available ‘any two from’ is
LL
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.
A
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.
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 ‘List’ 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.
3
Page 3 of 33
, 000004
MARK SCHEME – A-LEVEL CHEMISTRY – 7405/3 – JUNE 2024
However, responses considered to be neutral (often prefaced by ‘Ignore’ in the mark
scheme) are not penalised.
For example, in a question requiring 2 answers for 2 marks:
Incorrect
Correct answers (i.e.
Mark (2) Comment
answers incorrect rather
than neutral)
1 0 1
T
They have not exceeded the maximum
1 1 1 number of responses so there is no
penalty.
ES
They have exceeded the maximum number
1 2 0 of responses so the extra incorrect
response cancels the correct one.
2 0 2
2 1 1
B
2 2 0
E
3 0 2 The maximum mark is 2
The incorrect response cancels out one of
TH
3 1 1 the two correct responses that gained
credit.
Two incorrect responses cancel out the two
3 2 0
marks gained.
3 3 0
LL
3.2 Marking procedure for calculations
Full marks should be awarded for a correct numerical answer, without any working
A
shown, unless the question states ‘Show your working’ or ‘justify your answer’. In this
case, the mark scheme will clearly indicate what is required to gain full credit.
If an answer to a calculation is incorrect and working is shown, process mark(s) can
usually be gained by correct substitution / working and this is shown in the ‘Comments’
column or by each stage of a longer calculation.
3.3 Errors carried forward, consequential marking and arithmetic errors
Allowances for errors carried forward are most likely to be restricted to calculation
questions and should be shown by the abbreviation ECF or consequential in the marking
scheme.
4
Page 4 of 33
