Question

For $A\to B,\Delta H=4{\text{kcal mol}}^{-1}$, $\Delta S=10{\text{cal mol}}^{-1}{K}^{-1}$. Reaction is spontaneous when temperature is:

• A. $400$K
• B. $300$K
• C. $500$K
• D. None of these

Answer 1

Answer: (A)

$400$K

For a spontaneous reaction $\Delta H-T\Delta S<0$

Reaction will be spontaneous if $T>\frac{\Delta H}{\Delta S}$

Reaction will be spontaneous if $T>\frac{4000}{10}$

$T>400K$