A laboratory gas generator produces a gas when a solution of reactant P is added to excess powdered reactant Q. The gas is collected in a gas syringe.
The initial rate of the reaction is directly proportional to the initial concentration of P. The temperature, the volume of solution and the mass of powdered Q are the same in each experiment. Each experiment contains enough P to produce more than 50 cm3 of gas.
The table shows information about two experiments.
| Experiment | Initial concentration of P (mol/dm3\text{mol/dm}^3mol/dm3) | Volume of gas (cm3\text{cm}^3cm3) | Time (s) |
|---|---|---|---|
| 1 | 0.24 | 15 | 20 |
| 2 | 0.40 | 50 | ? |
Assume that the rate of gas production in experiment 1 was constant during the first 20 s.
Calculate the expected time to collect 50 cm3 of gas in experiment 2 if the initial rate remained constant.
The table shows the results obtained during experiment 2.
| Time (s) | Volume of gas collected (cm3\text{cm}^3cm3) |
|---|---|
| 0 | 0 |
| 10 | 12 |
| 40 | 38 |
| 50 | 43 |
Use the data and ideas about particles to explain why the time needed to collect 50 cm3 of gas is longer than calculated in part (a).
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.