For a given chemical reaction, the enthalpy change is +35.5 kJ/mol and the entropy change is +83.6 J — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

The criterion for spontaneity is $\Delta G = \Delta H - T\Delta S < 0$. When both are positive, the reaction is driven by entropy and becomes spontaneous only at high temperatures. Setting $\Delta G < 0$ gives $T > \Delta H / \Delta S = 35500 / 83.6 \approx 424.6 \text{ K}$.