Question

A reaction, A + B $\to$ C + D + q is found to have a positive entropy change. The reaction will be
(i) possible at high temperature
(ii) possible only at low temperature
(iii) not possible at any temperature
(iv) possible at any temperature

Answer 1

For a reaction to be spontaneous, $\Delta G$ should be negative.
$\Delta G=\Delta H–T\Delta S$
According to the question, for the given reaction,
$\Delta S$ = positive
$\Delta H$ = negative (since heat is evolved)
$\Rightarrow \Delta G$ = negative
Therefore, the reaction is spontaneous at any temperature.
Hence, alternative (iv) is correct.