In which of the following cases, the reaction is spontaneous at all temperatures ? — Thermodynamics and Thermochemistry Chemistry Question

💡 Solution & Explanation

I don't see the options A, B, C, D provided in your question. To give you a complete solution explaining why B is correct, I need to see all the answer choices. However, I can explain the **general principle** for spontaneity at all temperatures: ## Thermodynamic Criterion for Spontaneity A reaction is spontaneous at all temperatures when: $$\Delta G = \Delta H - T\Delta S < 0 \text{ at all } T$$ This requires: - $\Delta H < 0$ (exothermic) - $\Delta S > 0$ (entropy increases) **Why?** The $T\Delta S$ term dominates at high temperatures. If both $\Delta H$ and $\Delta S$ are positive, the reaction becomes non-spontaneous at low $T$ (where $\Delta H$ dominates). Conversely, if both are negative, it becomes non-spontaneous at high $T$. Only when $\Delta H < 0$ and $\Delta S > 0$ is $\Delta G$ always negative. --- **Please provide options A, B, C, D** so I can specifically explain why B is the correct case and why the others fail this criterion.