A student investigates how temperature affects the rate of a reaction between two solutions. The student records the time taken for the mixture to reach the same stage of a colour change. All other conditions not shown in the table are kept the same.
| Experiment | Temperature | Concentration of solution X | Time taken / s |
|---|---|---|---|
| A | 20 ∘C20\,^\circ\mathrm{C}20∘C | dilute | 82 |
| B | 30 ∘C30\,^\circ\mathrm{C}30∘C | dilute | 43 |
| C | 30 ∘C30\,^\circ\mathrm{C}30∘C | concentrated | 24 |
Which two experiments provide valid evidence for the effect of temperature on the rate? Explain how the results support your answer.
Calculate the relative rates for experiments B and C. Use your answers to describe the effect of the concentration of solution X on the rate.
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.