Discussion Forum



1)

A certain reaction is non spontaneous at 298K. The entropy change during the reaction is 121 JK-1 . Is the reaction is endothermic or exothermic ? The minimum value of ΔH for the reaction is


A) endothermic, $\triangle H$ = 36.06kJ

B) exothermic, $\triangle H$ = -36.06kJ

C) endothermic, $\triangle H$ = 60.12kJ

D) exothermic, $\triangle H$ = -60.12kJ

Answer:

Option A

Explanation:

For non spontaneous reaction ΔG =+ve, ΔG = ΔH -TΔS and ΔS = 121 JK-1

For ΔG =+ve

ΔH has to be positive. Here the reaction is endothermic.

The minimum value of ΔH can be obtained by putting  ΔG = 0, ΔH = TΔS = 298 x 121 J = 36.06 KJ