Gas X reacts reversibly to form gas Y. The reaction is represented by:
X(g)⇌Y(g) \mathrm{X(g) \rightleftharpoons Y(g)} X(g)⇌Y(g)A sample is placed in a closed container. The amounts of X and Y are measured at intervals.
| Time in seconds | Amount of X in mol | Amount of Y in mol |
|---|---|---|
| 0 | 1.00 | 0.00 |
| 20 | 0.74 | 0.26 |
| 40 | 0.60 | 0.40 |
| 60 | 0.60 | 0.40 |
| 80 | 0.60 | 0.40 |
From the data, state the first time at which dynamic equilibrium is shown.
Compare the rates of the forward and reverse reactions during the first 20 seconds. Explain your answer using the amount of Y.
At 80 s, more X is injected into the container, which is then resealed. The temperature is kept the same.
Predict how the position of equilibrium changes. Explain your answer.
124 exam-style questions on OCR GCSE Chemistry 5.3 Equilibria, covering 5.3.1 Reversible reactions and dynamic equilibrium and 5.3.2 Changing the position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.