At 20 ∘C20\,^\circ\mathrm{C}20∘C, the cross under a flask disappears 96 s after sodium thiosulfate solution and hydrochloric acid are mixed.
The rate of this reaction doubles for every 10 ∘C10\,^\circ\mathrm{C}10∘C rise in temperature.
How long should the cross take to disappear at 50 ∘C50\,^\circ\mathrm{C}50∘C?
12 s
24 s
32 s
48 s
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.