A reaction has ΔH° = 61.9 kJ/mol and ΔS° = 405.4 J/K.Is this reaction spontaneous or nonspontaneous? At what temperature (if any)can the spontaneity be reversed?

Question

Quizplus · Accepted Answer

The spontaneity of a reaction can be determined by the Gibbs free energy change (ΔG°), which is given by ΔG° = ΔH° - TΔS°. For a reaction to be spontaneous, ΔG° must be negative. The temperature at which the spontaneity can be reversed is found when ΔG° = 0, which gives T = ΔH°/ΔS°. Using the given values, T = (61.9 kJ/mol) / (405.4 J/K * 1 kJ/1000 J) = 152.7 K. Therefore, the reaction is spontaneous at temperatures above 152.7 K and can be made nonspontaneous below this temperature.

A Reaction Has ΔH° = 61