A large excess of 2-bromo-2-methylpropane is added to 0.0010mol of NaOH(aq), which contains
a few drops of phenolphthalein indicator. A stopwatch is started as soon as the substances are
mixed. The time taken for the pink colour to disappear is recorded.
The experiment is repeated at different temperatures, keeping all concentrations and volumes of
reagents constant.
temperature /°C | time taken for pink colour to disappear/s
20 | 300
25 | 65
35 | 20
[Figure showing Maxwell-Boltzmann distribution curve with Ea marked] proportion of molecules with a given energy 0 Ea molecular energy

Q: What topic does this question test?

This question tests Reaction kinetics in A-Level Chemistry (syllabus code 9701). It is worth 11 marks.

Q: Which exam paper is this question from?

This question appeared in the Cambridge A-Level Chemistry May/June 2021 examination, Paper 2 Variant 2 (9701_s21_qp_22.pdf).

Question

A large excess of 2-bromo-2-methylpropane is added to 0.0010mol of NaOH(aq), which contains
a few drops of phenolphthalein indicator. A stopwatch is started as soon as the substances are
mixed. The time taken for the pink colour to disappear is recorded.
The experiment is repeated at different temperatures, keeping all concentrations and volumes of
reagents constant.
temperature /°C | time taken for pink colour to disappear/s
20 | 300
25 | 65
35 | 20
[Figure showing Maxwell-Boltzmann distribution curve with Ea marked] proportion of molecules with a given energy 0 Ea molecular energy

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