Question

If an endothermic reaction is non-spontaneous at freezing point of water and becomes feasible at its boiling point, then
(a) ΔH is –ve, ΔS is +ve
(b) ΔH and ΔS both are +ve
(c) ΔH and ΔS both are –ve
(d) ΔH is +ve, ΔS is –ve

Answer 1

(b) : For endothermic reaction, ΔH = +ve
Now, ΔG = ΔH – TΔS
For nonspontaneous
reaction, ΔG should be positive
Now ΔG is positive at low temperature if ΔH is positive.
ΔG is negative at high temperature if ΔS is positive.