Thermodynamics and ThermochemistrymediumINTEGER

At 298 K, the standard enthalpy of combustion of sucrose is and the standard Gibb's energy of the reThermodynamics and Thermochemistry Chemistry Question

Question

At 298 K, the standard enthalpy of combustion of sucrose is $-5737\text{ kJ mol}^{-1}$ and the standard Gibb's energy of the reaction is $-6333\text{ kJ mol}^{-1}$. The additional (non-expansion) work (in kJ) that may be obtained by raising the temperature to $29^\circ\text{C}$ is

Answer: 8

💡 Solution & Explanation

At 298 K: $\Delta G = \Delta H - T\Delta S \implies -6333 = -5737 - 298\Delta S \implies \Delta S = \frac{5737 - 6333}{-298} = 2\text{ kJ/K-mol}$. The maximum non-expansion work obtainable is $-\Delta G$. At $29^\circ\text{C}$ (302 K): $\Delta G_{302} = \Delta H - T_2\Delta S = -5737 - 302(2) = -6341\text{ kJ/mol}$. Work at 298 K $= 6333\text{ kJ}$. Work at 302 K $= 6341\text{ kJ}$. Additional work $= 6341 - 6333 = 8\text{ kJ}$.

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