The gases X, Y and Z react reversibly in a sealed container.
X(g)+Y(g)⇌Z(g) \mathrm{X(g) + Y(g) \rightleftharpoons Z(g)} X(g)+Y(g)⇌Z(g)The mixture is allowed to reach dynamic equilibrium. Some Z is removed and the container is sealed again. The temperature and volume do not change.
How does the mixture change between removing Z and reaching equilibrium again?
More X and Y form and some remaining Z is used up.
No further change occurs because both reactions stop at equilibrium.
More Z forms and some X and Y are used up.
Only the amount of Z changes because X and Y were not removed.
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.