Question

A reaction is spontaneous at low temperature, but nonspontaneous at high temperature. Which of the following condition is true for the chemical reaction?

• A. $\Delta H < 0, \Delta S< 0$
• B. $\Delta H > 0, \Delta S=0$
• C. $\Delta H < 0, \Delta S > 0$
• D. $\Delta H > 0, \Delta S > 0$

Answer 1

Answer: (A)

$\Delta H< 0, \Delta S< 0$
$\Delta G=\Delta H-T \Delta S$
When, $\Delta H <0$ and $\Delta S <0$, then $\Delta G$ will be negative only at low temperature.