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5.2 Controlling reactions

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Question 4
F

A student times how long it takes for a cross under a flask to disappear when sodium thiosulfate solution reacts with dilute hydrochloric acid.

With one concentration of sodium thiosulfate solution, the cross disappears after 120 s.

The rate of this reaction is directly proportional to the concentration of sodium thiosulfate. Everything else stays the same.

The student repeats the experiment with sodium thiosulfate solution that is three times as concentrated.

How long should it take for the cross to disappear?

[1]
A

13 s

B

40 s

C

60 s

D

360 s

Markscheme

5.2 Controlling reactions Questions

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

56 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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