2 hours allowed
You should have access to the AQA insert (periodic table and data sheet)
to help with answering the questions.
Grade boundaries
These are VERY rough guesses! Getting a Possible Marks
Question
marks gained
C on this paper does not guarantee you
1 7
the same mark in the exam.
2 15
3 13
4 14
A* - 90 5 11
A – 80 SECTION B 30
B – 70 Total 90
C – 60
D – 50
E - 40
1
,aq
2
,aq
SECTION A
01
A sample of hydrated K 2SO4 (K2SO4.𝑥H2O) with a mass of 2.458 g was
heated to remove all water of crystallisation. The solid remaining had a
mass of 1.515 g.
(The molar mass of the remaining solid was 174.26 gmol-1)
01.1 Determine a possible formula of the hydrated potassium salt.
Your answer must show relevant working.
[3 marks]
01.2 Suggest how a student doing this experiment could check that all
water had been removed.
[1 mark]
01.3 The entropy change of hydration of K2SO4 is + 225 JK-1mol-1
i) Suggest in terms of the states of the particles involved, why this
entropy change is positive.
[1 mark]
ii) Explain why K2SO4 dissolves in water at 25°C, despite the
enthalpy change of solution being endothermic.
ΔH = +24 kJmol-1
[2 marks]
3
, aq
02
A student wants to investigate the kinetics of the reaction between
hydrogen peroxide and iodide ions in the presence of sulfuric acid.
Rate = [H2O2]x[I-]y
02.1 Write the balanced chemical equation for the reaction between
hydrogen peroxide and iodide ions.
[Include state symbols]
[2 marks]
02.2 The concentration of hydrogen peroxide is measure at different time
intervals while keeping the concentration of iodide and H+ ions
constant. The student could obtain the following results.
t/ 103 s [H2O2]/moldm-
3
0 0.20
2 0.14
4 0.09
6 0.06
8 0.04
10 0.03
i)
Plot the graph of [H2O2]/ moldm-3 against / 103 s
[2 marks]
4
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