Question

If an endothermic reaction is non-spontaneous at freezing point of water and becomes feasible at its boiling point then
A. `DeltaH` is -ve, `DeltaS` is + ve
B. `DeltaH` and `DeltaS` both are + ve
C. `DeltaH` and `DeltaS` both are -ve
D. `DeltaH` is +ve, `DeltaS` is -ve

Answer 1

Correct Answer - B
For a reaction to be spontaneous, `DeltaG` must be negative, According to the equation -
`DeltaG=DeltaH-T.DeltaS`
If `DeltaH` and `DeltaS` both are positive, than term T. `DeltaS` will be greater than `DeltaH` at high temperature and consequently `DeltaG` will be negative at high temperature.