AQA A-Level Chemistry Paper 2, 2017: Question 7

07.1 This question is marked using Levels of Response. Refer to the Indicative Chemistry content

Mark Scheme Instructions for Examiners for guidance.

Stage 1: An initial test to separate into two groups (2 groups

Level 3 All stages are covered and each stage is generally of 2 OR 1 group of 3 and 1 group of 1)

correct and virtually complete.

5-6 marks Stage 2: An second test to distinguish within a group or to

Answer is communicated coherently and shows a separate into two further groups

logical progression from Stage 1 to Stages 2 and 3 to

distinguish all the compounds with results for all Stage 3: A third test leads to a set of results/observations

remaining compounds stated. which distinguishes between all 4 compounds

Describing subsequent organic test on product Tests must include reagent and observation which identifies

(unnecessary) - limits to lower mark in level compound(s)

-COOH

Level 2 All stages are covered but stage(s) may be incomplete

a) NaHCO3 / Na2CO3 (or correct alternative)

or may contain inaccuracies

3-4 marks b) effervescence /gas turns limewater milky

OR two stages are covered and are generally correct

c) K and /or M but not L and/or N

and virtually complete.

-OH and -CHO

Answer is communicated mainly coherently and shows d) acidified K2Cr2O7

a logical progression from Stage 1 to Stages 2 and 3. e) solution turns green

f) K and/or L and/or N but not M

Describing subsequent organic test on product

-CHO

(unnecessary) - limits to lower mark in level

g) Fehlings OR Tollens

h) red ppt OR silver mirror

Level 1 Two stages are covered but stage(s) may be incomplete

i) N only but not K and/or L and/or M

or may contain inaccuracies OR only one stage is

1-2 marks -Br

covered but is generally correct and virtually complete.

j) Silver nitrate

Answer includes isolated statements but these are not k) cream ppt

presented in a logical order. l) L and/or N but not K and/or M

Isolated tests on individual compounds– - max LEVEL 2––

0 mark Insufficient correct chemistry to gain a mark. Isolated tests not linked to any compound – max LEVEL 1

Penalise observation if deduction wrong, but allow

observation if deduction incomplete

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Alternative tests

-COOH -COOH -OH only

a) named alcohol & H2SO4 a) named indicator m) named carboxylic acid & H2SO4

b) sweet smell (of ester) b) correct colour n) sweet smell (of ester)

c) K and /or M but not L and/or N c) K and /or M but not L and/or N o) K and/or L but not M and /or N

H CH3 CH3 CH3

H3C C COOH H3C C CH2OH H3C C COOH H3C C CHO

OH Br H Br

Test Tests

K L M N

for

a) NaHCO3 / Mg / Indicator K M × ×

d) K Cr O / H+ K L N ×

22 7

g) Fehlings / Tollens N × × ×

j) AgNO3 see Note * L N × ×

a) named alcohol & H2SO4 K M × ×

m) named carboxylic acid & K L × ×

H2SO4

Note * allow NaOH then HNO3, AgNO3 as one test; but treat NaOH, AgNO3 without acid as incomplete,so can mark on.