JAMB Chemistry 2010 Paper

Concept:A spontaneous reaction is favoured by a negative change in Gibbs free energy, $\Delta G$.When heat is released and disorder increases, the free energy of the system falls sharply.Explanation:An exothermic reaction releases heat, so the enthalpy change is negative: $\Delta H < 0$.A great disorder means the entropy change is positive: $\Delta S > 0$.The Gibbs free energy relation is $\Delta G = \Delta H - T\Delta S$.Since $\Delta H$ is negative and $-T\Delta S$ is also negative, $\Delta G$ becomes largely negative.A large negative $\Delta G$ indicates a highly spontaneous process with a large decrease in free energy.Therefore, the reaction is neither static nor at equilibrium; it proceeds readily in the forward direction.Answer:D. There will be a large decrease in free energy.