JAMB Chemistry 2010 Paper

Concept:The reaction is exothermic, so temperature changes affect the equilibrium constant.Explanation:The forward reaction gives out heat: $\mathrm{2H_2(g) + O_2(g) \rightleftharpoons 2H_2O(g)}$, $\Delta H = -ve$.Increasing the temperature adds heat to the system.According to Le Chatelier’s principle, the equilibrium shifts to the left to absorb the extra heat.This favors the reactants and reduces the value of the equilibrium constant, $K$.Therefore, $K$ decreases when temperature is increased.Answer:C. it decreases.