A reaction between solutions X and Y produces a blue colour. A chemist records the time taken for the mixture to reach a fixed shade of blue.
The same volume of each solution is used in every experiment. The concentration of solution Y and all other conditions are kept the same. The same person judges the endpoint each time.
| Experiment | Concentration of solution X in g/dm³ | Temperature in °C | Time in s |
|---|---|---|---|
| A | 10 | 20 | 92 |
| B | 20 | 20 | 48 |
| C | 10 | 30 | 43 |
Calculate the ratio of the relative rate in experiment B to the relative rate in experiment A and the ratio of the relative rate in experiment C to the relative rate in experiment A.
Give each answer to two significant figures.
Use collision theory to explain the differences between the results for experiments A, B and C.
Experiment D uses solution X with a concentration of 20 g/dm³ at 30 °C. Compare the proportion of collisions with at least the activation energy in experiment D with the proportion in experiment C. Justify your answer.
122 exam-style questions on Edexcel GCSE Chemistry 8.1 Rates of reaction, covering 8.1.1 Measuring and interpreting rates of reaction, 8.1.2 Collision theory and the factors affecting rate, and 8.1.3 Catalysts and enzymes. Each one has a worked solution and a mark scheme showing where the marks go.