Solutions P and Q react to produce a gas.
In each experiment, a student mixes 25 cm3 of solution P with 50 cm3 of solution Q. Solution Q is in excess. The temperature is kept constant.
The student measures the time taken to collect 20 cm3 of gas.
| Experiment | Concentration of P in mol/dm3\mathrm{mol/dm^3}mol/dm3 | Time in s |
|---|---|---|
| 1 | 0.15 | 100 |
| 2 | 0.30 | 50 |
| 3 | 0.60 | 25 |
| 4 | 0.45 | not measured |
Explain why the time taken becomes shorter as the concentration of P increases.
Use the results to calculate the expected time for experiment 4.
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.