JAMB Chemistry 2011 Paper

Concept:For an endothermic reaction, increasing temperature shifts equilibrium to favor the forward reaction and increases the equilibrium constant.Explanation:The reaction $\mathrm{N_2O_{4(g)}} \rightleftharpoons 2\mathrm{NO_{2(g)}}$ has $\Delta H = +\text{ve}$, meaning heat is absorbed in the forward direction.Increasing temperature adds heat, so by Le Chatelier’s principle, the equilibrium shifts to the right, producing more $\mathrm{NO_2}$.Since the forward reaction is endothermic, an increase in temperature increases the value of the equilibrium constant, $K$.Answer:A. increase the value of the equilibrium constant