Question

In a reaction $\Delta H$ and $\Delta S$ both are positive. In which of the following cases, the reaction would not be spontaneous?

• A. $\Delta H>T\Delta S$
• B. $T\Delta S>\Delta H$
• C. $\Delta H=T\Delta S$
• D. All of these

Answer 1

The correct option is C $\Delta H=T\Delta S$

Gibbs free energy $\Delta G=\Delta H-T\Delta S$

When $\Delta G$ is negative $(T\Delta S>\Delta H)$, a process or chemical reaction proceeds spontaneously in the forward direction.

When $\Delta G$ is positive$(\Delta H>T\Delta S)$, the process proceeds spontaneously in reverse.

When$\Delta G$ is zero, $(\Delta H=T\Delta S)$the process is already in equilibrium, with no net change taking place over time.