Standard entropies of $ ext{X}_2$, $ ext{Y}_2$ and $ ext{XY}_5$ are $70, 50$ and $110\ ext{J K}^{-1} ext{mol}^{-1}$ respectively. The temperature in Kelvin at which the reaction $\frac12 ext{X}_2+\frac52 ext{Y}_2 ightleftharpoons ext{XY}_5$, $\Delta H^\Theta=-35\ ext{kJ mol}^{-1}$ will be in equilibrium is ______. (Nearest integer)

Question

Standard entropies of $	ext{X}_2$, $	ext{Y}_2$ and $	ext{XY}_5$ are $70, 50$ and $110\ 	ext{J K}^{-1}	ext{mol}^{-1}$ respectively. The temperature in Kelvin at which the reaction $\frac12	ext{X}_2+\frac52	ext{Y}_2ightleftharpoons	ext{XY}_5$, $\Delta H^\Theta=-35\ 	ext{kJ mol}^{-1}$ will be in equilibrium is ______. (Nearest integer)

Dr. Abubacker · Accepted Answer

[Solution by Dr. Abubacker] $\Delta S=110-\left(\frac12\cdot70+\frac52\cdot50ight)=110-160=-50\ 	ext{J K}^{-1}$. At equilibrium $\Delta G=0$: $T=\frac{\Delta H}{\Delta S}=\frac{-35000}{-50}=700$ K. Answer: 700.

Explanation

Reviewed by Dr. Abubacker

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