AQA-8402-1-W-MS-Jan14
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AQA Level 1/2 Certificate Chemistry Paper 1 (8402/1) Mark scheme 8402 January 2014 Version/Stage: Final
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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 Assessment Writer. 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 years 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 2014 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 AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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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 and help to delineate
what 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.
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
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.
3. Marking points
3.1 Marking of lists This applies to questions requiring a set number of responses, but for which candidates 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)
Candidate Response Marks awarded
1 green, 5 0 2 red*, 5 1 3 red*, 8 0
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Example 2: Name two planets in the solar system. (2 marks)
Candidate Response Marks awarded 1 Neptune, Mars, Moon 1 2 Neptune, Sun, Mars,
Moon 0
3.2 Use of chemical symbols / formulae
If a candidate 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 Full marks can be given for a correct numerical answer, without any working shown.
However, if the answer is incorrect, mark(s) can be gained by correct substitution / working and this is shown in the extra information column or by each stage of a longer calculation.
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.
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 are 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 e.c.f. 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 Ignore / Insufficient / Do not allow Ignore of insufficient 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.
Do not allow means that this is a wrong answer which, even if the correct answer is given, will still mean that the mark is not awarded.
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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4. Quality of Communication and levels marking In Question 5(c) candidates are required to produce extended written material in English, and will be assessed on the quality of their written communication as well as the standard of the scientific response. Candidates will be required to: use good English organise information clearly use specialist vocabulary where appropriate. The following general criteria should be used to assign marks to a level: Level 1: basic Knowledge of basic information Simple understanding The answer is poorly organised, with almost no specialist terms and their use
demonstrating a general lack of understanding of their meaning, little or no detail The spelling, punctuation and grammar are very weak. Level 2: clear Knowledge of accurate information Clear understanding The answer has some structure and organisation, use of specialist terms has been
attempted but not always accurately, some detail is given There is reasonable accuracy in spelling, punctuation and grammar, although there may
still be some errors. Level 3: detailed Knowledge of accurate information appropriately contextualised Detailed understanding, supported by relevant evidence and examples Answer is coherent and in an organised, logical sequence, containing a wide range of
appropriate or relevant specialist terms used accurately. The answer shows almost faultless spelling, punctuation and grammar.
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
1(a)(i)
Neutron (top label)
Electron (bottom label)
1
1
AO1
1.2c
1(a)(ii)
13 1 AO1
1.2i
1(a)(iii)
electrons 1 AO1
1.2e
1(b)(i)
compound
hydrogen
bond
1
1
1
2AO1/1AO2
1.2b, 1.3a, 8.2a, 8.2b
1(b)(ii)
C4H10 1 AO2
8.2b
Total 8
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
2(a)(i)
iron
carbon dioxide
either order 1
1
AO2
1.3f, 6.2b
2(a)(ii)
reduced 1 AO1
6.2b
2(b)(i)
each correct line gains 1 mark
extra lines from statement negate the mark
max. 2
AO1
1.2a, 14.2a
2(b)(ii)
the layers / rows are distorted / disrupted or it doesnt occur in layers or the atoms are different so cannot slide over one another or slide less easily
1
1
AO1/AO2
6.3e
Total 7
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
3(a)(i)
Solids 1 AO1
3.2b
3(a)(ii)
Chlorine 1 AO1
3.2b
3(a)(iii)
improves dental health or reduces tooth decay
1 AO1
3.2d
3(b)
put a sample of the filtered water in an evaporating basin or leave to evaporate
there will be crystals of salt left
accept any description of evaporation (using a Bunsen or leaving on the windowsill)
1
1
AO1/AO2
3.2a, 3.2c
3(c)(i)
Test flame test Result yellow / orange / persistent orange flame
1
1
AO1
14.1e
3(c)(ii)
sodium and / or chloride ions are bigger than water (molecules) or ions are charged or molecules are not charged
do not accept sodium chloride molecules as ions is given in the question
1 AO3
3.2a, 14.2a
Total 8
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
4(a)
colourless ignore clear 1 AO1
9.1d
4(b)(i)
decomposition 1 AO1
9.1a
4(b)(ii)
C8H18 1 AO2
1.3f, 9.1b
4(c)(i)
two single trailing bonds extending from the carbons (through the brackets) 1 mark five single bonds (1 CC bond and 4 CH bonds) 1 mark
2 AO1
9.2a
4(c)(ii)
any two from:
(polymers made from) cornstarch are biodegradable
less space needed in landfill sites
polymers from cornstarch come from a renewable source.
allow converse for poly(ethene)
2 AO1/AO3
9.2e, 9.2f
Total 7
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
5(a)(i)
covalent 1 AO1
2.1g, 2.1h
5(a)(ii)
increases the rate of reaction 1 AO1
7g
5(b)(i)
the reaction is reversible 1 AO1
1.3i, 12b
5(b)(ii)
at lower pressure the molecules will be further apart
so there will be fewer collisions per unit time
accept frequency of collisions lower
1
1
AO2
12f
5(b)(iii)
as the temperature increases, the yield of the reaction increases
1 AO2
12g
5(b)(iv)
2 molecules / volumes become 4 or more molecules / volumes of product than reactant
1 AO1
7d
Question 5 continues on the next page
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question 5 continued
5(c) 6 marks 1AO1/2AO2/3AO3 1.1a, 8.3a, 8.3c, 8.3f
Marks awarded for this answer will be determined by the Quality of Communication (QoC) as well as the standard of the scientific response. Examiners should also refer to the information on page 5, and apply a best-fit approach to the marking.
0 marks Level 1 (12 marks) Level 2 (34 marks) Level 3 (56 marks)
No relevant content Candidate has written about some basic points from the table but has not added any extra knowledge. Candidate may have included advantages or disadvantages.
Candidate has attempted an evaluation using points from the table and their own knowledge. Candidate has included advantages and disadvantages.
Candidate has given an evaluation that includes both advantages and disadvantages. Candidate has clearly linked points from the table with their own knowledge and uses appropriate scientific terminology.
examples of the points made in the response Advantages of using hydrogen:
its combustion only produces water combustion of hydrogen does not
produce carbon dioxide or does not contribute to climate change
petrol requires much more oxygen to burn so partial combustion is possible producing carbon monoxide
combustion of hydrogen does not produce any particulates or does not contribute to global dimming
petrol comes from a non-renewable source or there are renewable ways of producing hydrogen, eg electrolysis of water.
Disadvantages of using hydrogen: hydrogen has to be stored at high
pressure or risk of explosion or larger volume needed for storage.
much less energy produced from the combustion of hydrogen or need to refuel more often
most methods of producing hydrogen need fossil fuels.
Total 13
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
6(a)
magnesium loses electrons
two electrons
chlorine gains electrons
two atoms of chlorine
there are four ideas here that need to be linked in two pairs.
magnesium loses electrons and chlorine gains electrons scores 2 marks.
magnesium loses two electrons and two chlorines each gain one electron will score full marks.
1
1
1
1
2AO1/2AO2
2.1c
6(b)
95 correct answer with or without working gains 2 marks if answer incorrect, allow 24 + 35.5 + 35.5 for 1 mark
2 AO2
1.3b
Total 6
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
7(a)(i)
ethanol 1 AO1
10.1a
7(a)(ii)
oxidised 1 AO1
10.1c
7(a)(iii)
Test add any named carbonate or hydrogen carbonate
Result A will effervesce (carbon dioxide) or B will not effervesce. or Test add a named (magnesium, aluminium, zinc, iron or tin) metal
Result A will effervesce (hydrogen), B will not
or Test add an acidbase indicator
Result credit any acid colour for that indicator eg for universal indicator allow red, yellow or orange
give credit for the neutral colour for B or Test add an alcohol (+ acid catalyst)
Result sweet or fruity smell of esters.
the first mark is for the test; the second is for the result
if the result is incorrect, award the first mark only
if the test is incorrect award 0 marks.
candidates do not have to name a gas but penalise an incorrect gas.
give credit to any test that will work.
allow a test that would identify B.
1
1
AO1/AO2
10.2b
Question 7 continues on the next page
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question 7 continued
Question Answers Extra information Mark AO/spec ref
7(b)(i)
H2O 1 AO2
1.3f, 10.2b
7(b)(ii)
ethyl ethanoate 1 AO1
10.3a
7(b)(iii)
any one from:
flavourings
perfumes
solvents
plasticisers
allow any correct use of esters 1 AO1
10.3b
Total 7
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
8(a)
any two from:
temperature (of the HCl) mass or length of the
magnesium surface area of the
magnesium volume of HCl
2 AO3
7d, 7f
8(b)(i)
(a greater concentration has) more particles per unit volume
therefore more collisions per unit time or more frequent collisions.
allow particles are closer together 1
1
AO1
7e
8(b)(ii)
particles move faster
therefore more collisions per unit time or more frequent collisions collisions more energetic (therefore more collisions have energy greater than the activation energy) or more productive collisions
allow particles have more (kinetic) energy
1
1
1
AO1
7c
8(c)(i)
add (a few drops) of indicator to the acid in the conical flask
add NaOH (from the burette) until the indicator changes colour or add the NaOH dropwise
repeat the titration
calculate the average volume of NaOH or repeat until concordant results are obtained
allow any named indicator
candidate does not have to state a colour change but penalise an incorrect colour change.
1
1
1
1
AO1
5.1h
8(c)(ii)
moles of NaOH 0.10 x 0.0272 = 0.00272 moles
Concentration of HCl 0.00272 / 0.005 = 0.544
correct number of significant figures
correct answer with or without working gains 3 marks
allow ecf from mp1 to mp2
1
1
1
AO2
5.1i
Total 14
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
9(a)(i)
giant lattice
atoms in in graphene are covalently bonded
and covalent bonds are strong or need a lot of energy to be broken
allow each carbon atom is joined to three others
max. 2 marks if any reference to wrong type of bonding
allow difficult to break
1
1
1
1AO1/2AO2
2.2f
9(a)(ii)
because graphene has delocalised electrons
which can move throughout the structure
allow each carbon atom has one free electron
do not accept just electrons can move.
1
1
AO1/AO2
2.2i
9(b)
because there are weak forces between molecules
so layers / molecules can slip / slide.
allow no bonds between the layers 1
1
AO1
2.2h
Total 7
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
10(a)
(24 x 12) x 100 = 67.6
426
or 426 x (67.6/100) = 288 288/12 = 24
1 AO2
1.3d
10(b)
5.65/12 2.2/14 0.629/1
0.471 0.157 0.629
3 1 4
C3NH4
correct answer of C3NH4 with no working scores 2 marks allow ecf from mp2 onwards
if the ratios are not shown but the correct working is shown for mp1 and mp2 , the ratio mark can be scored from C3NH4 if the initial fractions are inverted and the candidate gets an answer of C4N12H3 award 2 marks
1
1
1
1
AO2
1.3e
Total 5
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MARK SCHEME AQA Certificate in Chemistry Paper 1 8402/1 January 2014
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Question Answers Extra information Mark AO/spec ref
11(a)
products are at a lower energy level than reactants
activation energy correctly drawn and labelled
H correctly labelled
if candidate has drawn a profile for an endothermic reaction penalise first marking point only
1
1
1
2AO1/1AO2
11.2d
11(b)(i)
93 (kJ per mole)
correct answer with or without working gains 3 marks allow 2 marks for +93 kJ per mole if any other answer is seen award up to 2 marks for any two of the steps below:
bonds broken (614 + 193) = 807 (kJ) or (614 + 193 + (4 x 413)) = 2459(kJ)
bonds formed (348 + 276 + 276) = 900(kJ) or 348 + (2 x 276) + (4 x 413) = 2552(kJ)
bonds broken bonds formed
allow ecf for arithmetical errors
3 AO2
11.2e
11(b)(ii)
more energy is released when the bonds (in the products) are formed
than is needed to break the bonds (in the reactants)
if no other marks gained, allow 1 mark for energy released for bond making and energy used for bond breaking
1
1
AO1
11.2f
Total 8
AQA Level 1/2 Certificate