A gas-processing plant removes a pollutant gas, P, by reacting it with gas Q to form product R.
A scientist carries out four experiments using the same initial amounts of P and Q. The pressure is changed by adjusting the volume of the reaction chamber.
| Experiment | Temperature in °C | Pressure in kPa | Catalyst used | Mass of R after 20 s in g | Final mass of R in g |
|---|---|---|---|---|---|
| 1 | 25 | 100 | No | 2.4 | 8.0 |
| 2 | 45 | 100 | No | 4.1 | 8.0 |
| 3 | 45 | 200 | No | 6.3 | 8.0 |
| 4 | 45 | 200 | Yes | 7.5 | 8.0 |
Explain why more R was formed during the first 20 seconds in experiment 2 than in experiment 1.
Explain why more R was formed during the first 20 seconds in experiment 3 than in experiment 2.
Experiment 4 formed more R during the first 20 seconds than experiment 3, but the final mass of R was the same.
Explain both results.
127 exam-style questions on AQA GCSE Chemistry 6.1 Rate of reaction, covering 6.1.1a Calculating rates of reactions, 6.1.1b Gradient of a tangent as rate, 6.1.2 Factors which affect the rates of chemical reactions, 6.1.3 Collision theory and activation energy, and 6.1.4 Catalysts. Each one has a worked solution and a mark scheme showing where the marks go.