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5.2 Controlling reactions

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Question 19
F

At 20 ∘C20\,^\circ\mathrm{C}20∘C, the cross under a flask disappears 60 s after sodium thiosulfate solution and hydrochloric acid are mixed.

The student repeats the experiment at 30 ∘C30\,^\circ\mathrm{C}30∘C using sodium thiosulfate solution that is half as concentrated. Everything else stays the same.

  • The rate is directly proportional to the concentration of sodium thiosulfate.
  • The rate doubles for every 10 ∘C10\,^\circ\mathrm{C}10∘C rise in temperature.

How long should the cross take to disappear in the repeat experiment?

[1]
A

30 s

B

60 s

C

120 s

D

240 s

Markscheme

5.2 Controlling reactions Questions

  1. GCSE
  2. /Chemistry
  3. /5.2 Controlling reactions

122 exam-style questions on OCR GCSE Chemistry 5.2 Controlling reactions, covering 5.2.1 Measuring and interpreting rate of reaction, 5.2.2 Factors affecting rate and collision theory, and 5.2.3 Catalysts, activation energy and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.

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