Question

A reaction occurs spontaneously if

• A. $ T\Delta S<\Delta H $ and both $ \Delta H $ and $ \Delta S $ are $+ve$
• B. $ T\Delta S>\Delta H $ and both $ \Delta H $ and $ \Delta S $ are $+ve$
• C. $ T\Delta S=\Delta H $ and both $ \Delta H $ and $ \Delta S $ are $+ve$
• D. $ T\Delta S>\Delta H $ and $ \Delta H $ is + ve and $ \Delta S $ is $-ve$

Answer 1

Answer: (B)

The spontaneity of reaction is based upon the negative value of $\Delta G, \Delta G$ is based upon $T, \Delta S$ and $\Delta H$ according to following equation (Gibbs-Helmholtz equation)
$\Delta G=\Delta H-T \Delta S$
If the magnitude of $\Delta H-T \Delta S$ is negative, then the reaction is spontaneous.
when $T \Delta S>\Delta H$ and $\Delta H$ and $\Delta S$ are $+ ve$, then $\Delta G$ is negative.