A pink solution containing cobalt(II) ions is warmed and turns blue. The equilibrium in the solution is shown.
pink complex + 4Cl−4\text{Cl}^-4Cl− ⇌ \rightleftharpoons\,⇌ blue complex + 6H2O6\text{H}_2\text{O}6H2O
What does the colour change show about the forward reaction?
It is exothermic, because heating supplies energy to the mixture
It is exothermic, because the products are favoured by heating
It is endothermic, because heating shifts the equilibrium right
It is endothermic, because heating shifts the equilibrium left
40 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.