AqA A-level CHEMISTRY Paper 2 Organic and Physical Chemistry June 2023

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AqA


A-level
CHEMISTRY
Paper 2 Organic and Physical
Chemistry




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Answer all questions in the spaces box
provided.


This0 question
1 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]




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Figure 2 shows the results of this experiment when 25.0 cm3 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 cm 3 of a 2.23
mol dm–3 solution of chloroethanoic acid reacts with an excess of
NaHCO3

Suggest why chloroethanoic acid is a stronger acid than ethanoic acid.
[3 marks]




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