A reaction is spontaneous if:
I.ΔG is a negative value
II.both enthalpy and entropy increase
III.ΔH is negative and ΔS is positive
IV.both enthalpy and entropy decrease
V.ΔH is positive and ΔS is negative
A)I and III
B)I and II
C)II and V
D)III and IV
E)II and IV

Question

Quizplus · Accepted Answer

Only I and III are correct statements. ΔG indicates the spontaneity of a reaction, and a negative ΔG value implies that the reaction will proceed spontaneously. However, for a spontaneous reaction, the enthalpy change must be negative (ΔH < 0) to indicate an exothermic reaction and the entropy change must be positive (ΔS > 0) to indicate that the products are more disordered than the reactants. Therefore, statement III is also correct. Statements II, IV, and V are not correct because they present conflicting information or information that is not applicable to the spontaneity of a reaction.

A Reaction Is Spontaneous If