JAMB Chemistry 2022 Paper

Concept:The equilibrium position shifts according to Le Chatelier’s principle to oppose any change in temperature or pressure.Explanation:The reaction is $\mathrm{N_2O_4} \rightleftharpoons 2\mathrm{NO_2}$.The negative $\Delta$ means the forward reaction to produce $\mathrm{NO_2}$ is exothermic.Therefore, the reverse reaction that produces $\mathrm{N_2O_4}$ is endothermic.High temperature favours this endothermic reverse reaction, so more $\mathrm{N_2O_4}$ is formed.Also, the left side has 1 mole of gas, while the right side has 2 moles of gas.High pressure favours the side with fewer gas molecules, which is the $\mathrm{N_2O_4}$ side.Thus, high temperature and high pressure give the highest yield of $\mathrm{N_2O_4}$.Answer:D. High temperature and high pressure.