Question

If an endothermic reaction is non spontaneous, then

• A. $\Delta H\mathrm{is}\mathrm{negative},\Delta S\mathrm{is}\mathrm{positive}$
• B. $\Delta H\mathrm{and}\Delta S\mathrm{are}\mathrm{both}\mathrm{positive}$
• C. $\Delta H\mathrm{and}\Delta S\mathrm{are}\mathrm{both}\mathrm{negative}$
• D. $\Delta H\mathrm{is}\mathrm{positive},\Delta S\mathrm{is}\mathrm{negative}$

Answer 1

The correct option is D $\Delta H\mathrm{is}\mathrm{positive},\Delta S\mathrm{is}\mathrm{negative}$

For a non spontaneous process $\Delta G>0$. Since it is an endothermic process $\Delta H$ is positive. we know $\Delta G=\Delta H-T\Delta S$. Thus $\Delta S$ should be negative for an non spontaneous process