A manufacturer investigates the effect of adding substance Q on the conversion of liquid R into product S. The same mass of R is used under the same conditions in both experiments, and each reaction is allowed to finish.
| Experiment | Time for reaction to finish / s | Mass of S formed / g | Mass of Q before reaction / g | Mass of Q recovered / g |
|---|---|---|---|---|
| Q not added | 420 | 18.6 | - | - |
| Q added | 135 | 18.6 | 0.80 | 0.80 |
Explain how the results indicate that Q acts as a catalyst.
Explain how Q increases the rate of the reaction.
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.