What must be true of the free energy change, trangle G, for a reaction to be spontaneous? A) It must be negative
B) it must be greater than the change in entropy
C) It is dominated by the enthalpy change, (triangle H)
D) It must be driven by a large change in both entropy and enthalpy
E) It must be positive

A) It must be negative

Explanation:

A spontaneous reaction in Chemistry is that which is proceeding in a particular direction without the intervention of any external effect. As a spontaneous reaction proceeds (which can be relatively slow), free energy ΔG, which is the available energy for work, is released.

Gibbs free energy, ΔG, is released during a spontaneous process and hence the ΔG is negative because the reactants have more free energy than the products, hence, no energy input is needed for the reaction to proceed forward but rather an energy output. This is what makes a negative ΔG depict a spontaneous reaction.