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Edexcel A-Level Chemistry A2 11.3 Select and Justify a Suitable Experimental Technique to Obtain Rate Data for a Given Reaction Questions

Practise Edexcel IAL Chemistry 11.3 by matching colour, gas-volume, mass, conductivity or titration monitoring to the measurable change in each reaction.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
A2

Exam points

  • Choose colorimetry when a coloured species changes concentration during reaction.
  • Use gas volume or mass loss only when the stoichiometric change produces a measurable signal.
  • Distinguish continuous monitoring from quench-and-titrate sampling methods.

Edexcel A-Level Chemistry A2 11.3 Select and Justify a Suitable Experimental Technique to Obtain Rate Data for a Given Reaction Questions question 1

[Maximum number: 1]

A reaction vessel contained nitrogen monoxide and oxygen in a 2: 1 molar ratio. The mixture was allowed to come to equilibrium forming nitrogen dioxide. The equation for the reaction is shown.

2NO+O2⇌2NO22 \mathrm{NO}+\mathrm{O}_{2} \rightleftharpoons 2 \mathrm{NO}_{2}

The volume of the vessel was 15dm315 \mathrm{dm}^{3} and the reaction was carried out at a constant temperature and at a pressure of 200000 Pa .

At equilibrium there was a total of 0.69625 mol of gas in the reaction vessel and the mass of oxygen was 7.000 g .

Under a different set of conditions, the reaction was carried out to find the initial rate of reaction.

Table for Question Edexcel A-Level Chemistry A2 11.3 Select and Justify a Suitable Experimental Technique to Obtain Rate Data for a Given Reaction Questions question 1 — Edexcel A-Level Chemistry A2

The rate equation for this reaction is

 rate =k[NO]2[O2]\text { rate }=k[\mathrm{NO}]^{2}\left[\mathrm{O}_{2}\right]

Give the reason why colorimetry can be used to monitor the rate of the reaction.

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