AQA A-LEVEL CHEMISTRY PAPER 3 VERSION 1
AQA A-LEVEL CHEMISTRY PAPER 3 VERSION 1
A-level
CHEMISTRY
Paper 3
Wednesday 20 June 2018 Morning Time allowed: 2 hours
Materials
For this paper you must have:
• the Periodic Table/Data Booklet, provided as an insert (enclo...
aqa a level chemistry paper 3 version 1 a level chemistry paper 3 wednesday 20 june 2018 morning time allowed 2 hours materials for this paper you
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AQA A-LEVEL CHEMISTRY PAPER 3 VERSION 1
Please write clearly in block capitals.
Centre Candidate
number number
Surname
Forename(s)
Candidate ure
A-level
CHEMISTRY
Paper 3
Wednesday 20 June 2018 Morning Time allowed: 2 hours
Materials For Examiner’s Use
For this paper you must have:
the Periodic Table/Data Booklet, provided as an insert (enclosed) Question Mark
a ruler with millimetre measurements 1
a scientific calculator, which you are expected to use where appropriate. 2
3
Instructions
Use black ink or black ball-point pen. 4
Fill in the boxes at the top of the page. Section
Answer all questions. B
You must answer the questions in the spaces provided. Do not TOTAL
write outside the box around each page or on blank pages.
All working must be shown.
Do all rough work in this book. Cross through any work you do not
want to be marked.
Information
The marks for questions are shown in brackets.
The maximum mark for this paper is 90.
Advice
You are advised to spend about 70 minutes on Section A and 50 minutes on Section B.
,*jun1 7405301*
IB/M/Jun18/E10 7405/3
, Donot
Do not
2 write
write
outsidethe
outside the
box
box
Section A
Answer all questions in this section.
0 1 Iodide ions are oxidised to iodine by hydrogen peroxide in acidic conditions.
H2O2(aq) + 2H+(aq) + 2I–(aq) I2(aq) + 2H2O(l)
The rate equation for this reaction can be written as
rate = k [H2O2]a [I–]b [H+]c
In an experiment to determine the order with respect to H +(aq), a
reaction mixture is made containing H+(aq) with a concentration of 0.500
mol dm–3
A large excess of both H2O2 and I– is used in this reaction mixture so
that the rate equation can be simplified to
rate = k1 [H+]c
0 1 .1 Explain why the use of a large excess of H 2O2 and I– means that the rate of
reaction at a fixed temperature depends only on the concentration of H+
(aq).
[2 marks]
0 1 .2 Samples of the reaction mixture are removed at timed intervals and
titrated with alkali to determine the concentration of H+(aq).
State and explain what must be done to each sample before it is titrated with alkali.
[2 marks]
*02
IB/M/
* Jun18/7405/3
, Do not
3 write
outside the
box
0 1 .3 A graph of the results is shown in Figure 1.
Figure 1
Explain how the graph shows that the order with respect to H+(aq) is zero.
[2 marks]
0 1 .4 Use the graph in Figure 1 to calculate the
value of k1
Give the units of k1 [3 marks]
k1
Units
Turn over ►
*03
IB/M/
* Jun18/7405/3
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