Sulfur dioxide reacts with oxygen in a closed vessel to form sulfur trioxide.
2SO2(g)+O2(g)⇌2SO3(g)2\text{SO}_2\text{(g)} + \text{O}_2\text{(g)} \rightleftharpoons 2\text{SO}_3\text{(g)}2SO2(g)+O2(g)⇌2SO3(g)
When the mixture has reached equilibrium, the pressure is lowered. The temperature is kept the same.
Which statement about the change is correct?
The equilibrium stays the same, because every substance in the equation is a gas
The equilibrium moves to the left, because the left has three gas molecules and the right has two
The equilibrium stays the same, because both sides have two sulfur atoms and six oxygen atoms
The equilibrium moves to the left, because the left has two different gases and the right has one
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.