Question

A certain process has ΔH° > 0, ΔS° < 0, and ΔG° > 0. The values of ΔH° and ΔS° do not depend on the temperature. Which of the following is a correct conclusion about this process? None of the above conclusions is correct. It is non-spontaneous at all T. It is spontaneous at low T. It is spontaneous at all T. It is spontaneous at high T

Answer 1

Answer: It is non-spontaneous at all T.

Explanation:

According to Gibb's equation:

$\Delta G=\Delta H-T\Delta S$

$\Delta G$ = Gibbs free energy = +ve

$\Delta H$ = enthalpy change  = +ve

$\Delta S$ = entropy change  = -ve

T = temperature in Kelvin

$\Delta G$= +ve, reaction is non spontaneous

$\Delta G$= -ve, reaction is spontaneous

$\Delta G$= 0, reaction is in equilibrium

Putting in the values:

$\Delta G=(+ve)-T(-ve)$

$\Delta G=(+ve)(+ve)=+ve$  

Reaction is non spontaneous at all temperatures.