2023 AQA A-level CHEMISTRY 7405/2 Paper
2 Organic and Physical Chemistry Question
Paper & Mark scheme (Merged) June 2023
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A-level
CHEMISTRY
Paper 2 Organic and Physical Chemistry
Monday 19 June 2023 Afternoon 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
Instructions 3
• Use black ink or black ball-point pen.
4
• Fill in the boxes at the top of this page.
• Answer all questions. 5
• You must answer the questions in the spaces provided. Do not write outside 6
the box around each page or on blank pages. 7
• If you need extra space for your answer(s), use the lined pages at the end of 8
this book. Write the question number against your answer(s).
• All working must be shown. 9
• Do all rough work in this book. Cross through any work you do not want to TOTAL
be marked.
Information
• The marks for questions are shown in brackets.
• The maximum mark for this paper is 105.
, 2
Do not write
outside the
Answer all questions in the spaces provided. box
0 1This question is about rates of reaction.
Figure 1 shows apparatus used to measure the rate of reaction when an acid reacts
with an excess of solid sodium hydrogencarbonate, NaHCO3
When different monoprotic organic acids are used, the rates at which gas escapes
can be used to compare the strengths of the acids.
A timer is started when the NaHCO3 is added to the acid and
the mass of CO2 gas lost is recorded at regular intervals.
(It is assumed that any change in mass is due to the loss of CO2)
Figure 1
0 1 . 1 Suggest a reason why using a conical flask instead of a beaker would give
more accurate results in this experiment.
[1 mark]
*02*
IB/M/Jun23/7405/2
, 3
Do not write
3 outside the
Figure 2 shows the results of this experiment when 25.0 cm of a box
2.23 mol dm–3 solution of ethanoic acid reacts with an excess of NaHCO3
Figure 2
0 1.2 Use Figure 2 to calculate the rate of reaction at 2 minutes.
Deduce the units of your calculated rate.
[3 marks]
Rate Units
0 1.3 Chloroethanoic acid is a stronger acid than ethanoic acid.
Sketch, on Figure 2, the curve you would expect when 25.0 cm3 of a 2.23 mol dm–
3 solution of chloroethanoic acid reacts with an excess of NaHCO 3
Suggest why chloroethanoic acid is a stronger acid than ethanoic acid.
[3 marks]
7
Turn over ►
*03*
IB/M/Jun23/7405/2
, 4
Do not write
outside the
0 2A and B react together in the presence of an acid catalyst. A(aq) + box
2 B(aq) → C(aq) + D(aq)
The rate equation for this reaction is
2 +
rate = k[B] [H ]
Table 1 shows how the values of the relative initial rate vary with
different concentrations of each reagent at the same temperature.
0 2 . 1Complete Table 1 by calculating the missing values.
[3 marks]
0 2 . 2 A suggested mechanism for the reaction is shown.
Step 1 B + H+ → BH+
+ +
Step 2 BH + B → B2H Step 3
+
B2H +A→C+D
Deduce the rate-determining step for this
reaction. Give a reason for your answer.
[2 marks]
Rate-determining step
Reason
5
*04*
IB/M/Jun23/7405/2
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