Students investigate the rate of reaction between sodium thiosulfate solution and dilute nitric acid at different temperatures. They measure the time taken for a cross drawn on paper under the reaction flask to disappear from view due to the formation of a solid sulfur precipitate.
Their results are shown in the table below:
| Temperature (∘C^{\circ}\text{C}∘C) | Reaction time (s\text{s}s) | Rate of reaction (s−1\text{s}^{-1}s−1) |
|---|---|---|
| 15 | 125 | 8.0×10−38.0 \times 10^{-3}8.0×10−3 |
| 25 | 50 | 2.0×10−22.0 \times 10^{-2}2.0×10−2 |
| 35 | 32 | 3.1×10−23.1 \times 10^{-2}3.1×10−2 |
| 45 | 22 | 4.5×10−24.5 \times 10^{-2}4.5×10−2 |
| 55 | 17 | 5.9×10−25.9 \times 10^{-2}5.9×10−2 |
Describe the relationship between temperature and the rate of reaction.
Explain your answer to part (a) using collision theory. Include ideas about particle energy, collision frequency, and successful collisions.
In another trial at 65∘C65^{\circ}\text{C}65∘C, the reaction time was found to be 13 s13 \text{ s}13 s. Calculate the rate of reaction at this temperature. Give your answer in scientific notation to two significant figures.
31 exam-style questions on OCR GCSE Chemistry Controlling reactions. Each one has a worked solution and a mark scheme showing where the marks go.