If enthalpy change for following reaction at $300 \mathrm{~K}$ is $+7 \mathrm{~kJ} \mathrm{~mol}^{-1}$ find…

If enthalpy change for following reaction at $300 \mathrm{~K}$ is $+7 \mathrm{~kJ} \mathrm{~mol}^{-1}$ find the entropy change of surrounding? $\mathrm{H}_2 \mathrm{O}_{(\mathrm{s})} \longrightarrow \mathrm{H}_2 \mathrm{O}_{(l)}$
  1. $-42.8 \mathrm{~J} \mathrm{~K}^{-1}$
  2. $-23.3 \mathrm{~J} \mathrm{~K}^{-1}$
  3. $-30.7 \mathrm{~J} \mathrm{~K}^{-1}$
  4. $-110.0 \mathrm{~J} \mathrm{~K}^{-1}$

Solution

$\begin{aligned} \Delta \mathrm{S}_{\text {surr }} & =-\frac{\Delta \mathrm{H}^{\circ}}{\mathrm{T}}=-\frac{(+7 \mathrm{~kJ})}{300 \mathrm{~K}} \\ & =-0.00233 \mathrm{~kJ} \mathrm{~K}^{-1} \\ & =-23.3 \mathrm{~J} \mathrm{~K}^{-1}\end{aligned}$

Asked in: MHT CET 2023 (14 May Shift 1)

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