For a given reaction, Δ_rH = +35.5 kJ mol^-1 and Δ_rS = +83.6 J K^-1mol^-1. The reaction is spontaneous ________. Assume that Δ_rH and Δ_rS do not vary with temperature.

Question

Quizplus · Accepted Answer

The spontaneity of a reaction is determined by the Gibbs free energy change, which is given by ΔG = ΔH - TΔS. A reaction will be spontaneous if ΔG is negative. 
Using the given values, ΔS is positive and ΔH is positive, suggesting that the reaction is endothermic and entropy-driven. At low temperatures, the positive ΔH term dominates, making ΔG positive and the reaction non-spontaneous. At high temperatures, the negative TΔS term dominates and makes ΔG negative, therefore, the reaction is spontaneous at T > 425 K.

For a Given Reaction, ΔrH = +35

For a Given Reaction, Δ_rH = +35