`DeltaG` is the net energy available to do useful work and is a measure of free energy. If a reaction has positive enthalpy change and positive entropy change, under what conditions will the reaction be spontaneous?

Options

A. `DeltaG` will be positive at low temperature hence reaction is spontaneous at low temperature.
B. `DeltaG` is negative at high temperature hence reaction is spontaneous at high temperature.
C. `DeltaG` is negative at low temperature.
D. `DeltaG` is negative at all temperature hence reaction is spontaneous at all temperatures.

Answer

B

Explanation

`DeltaG=DeltaH-T DeltaS`
For a spontaneous reaction if `DeltaH` is +ve and `DeltaS=+ve,DeltaG` will be negative when `T DeltaS gt DeltaH`.