For a given reaction, ΔH = +22.2 kJ/mol and ΔS = +81.1 J/K-mol. The reaction is spontaneous ________. Assume that ΔH and ΔS do not vary with temperature.

Question

Quizplus · Accepted Answer

For a spontaneous reaction, ΔG should be negative (ΔG = ΔH - TΔS). Since ΔH is positive and ΔS is also positive, the spontaneity of the reaction will depend on the temperature. At low temperature, the ΔS term will dominate and make ΔG positive, making the reaction non-spontaneous. At high temperature, the TΔS term will dominate and make ΔG negative, making the reaction spontaneous. The transition temperature is calculated as ΔH/ΔS = 272.8 K. Therefore, the reaction will be spontaneous at temperatures above 274 K.

For a Given Reaction, ΔH = +22