A sealed container initially holds 0.80 mol of compound J and no other substances. When J is heated, it decomposes to form K and L. Each mole of J that decomposes forms one mole of K and one mole of L.
The amount of J is measured at the start, and again after it stops changing at each new temperature.
| Stage | Temperature in °C | Amount of J in mol |
|---|---|---|
| Start | 20 | 0.80 |
| After heating | 250 | 0.31 |
| After cooling | 20 | 0.78 |
Explain how the results show that the reaction can happen in both directions.
The container is reheated to 250 °C until the amount of J stops changing. It is then cooled to 20 °C again until the amount of J stops changing.
Calculate the expected amount of K in the container after the second cooling.
109 exam-style questions on AQA GCSE Chemistry 6.2 Reversible reactions and dynamic equilibrium, covering 6.2.1 Reversible reactions, 6.2.2 Energy changes and reversible reactions, 6.2.3 Equilibrium, 6.2.4 The effect of changing conditions on equilibrium, 6.2.5 The effect of changing concentration, 6.2.6 The effect of temperature changes on equilibrium, and 6.2.7 The effect of pressure changes on equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.