Gas R is made by a reversible reaction between gases P and Q.
P(g)+Q(g)⇌2R(g) \mathrm{P(g) + Q(g) \rightleftharpoons 2R(g)} P(g)+Q(g)⇌2R(g)The reaction mixture reaches equilibrium in a sealed container. Some R is then removed through a valve. The temperature and volume are kept constant.
| Stage | Amount of R in mol |
|---|---|
| At the original equilibrium | 0.80 |
| Immediately after R is removed | 0.30 |
| At the new equilibrium | 0.55 |
Explain how the amount of P at the new equilibrium compares with the amount at the original equilibrium.
Calculate the percentage of the removed R that is replaced by the time the new equilibrium is reached.
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.