The thermal decomposition of calcium carbonate is represented by the chemical equation:
CaCO3(s)→CaO(s)+CO2(g) \text{CaCO}_3(\text{s}) \rightarrow \text{CaO}(\text{s}) + \text{CO}_2(\text{g}) CaCO3(s)→CaO(s)+CO2(g)For this reaction, ΔH∘=+178 kJ mol−1\Delta H^\circ = +178\text{ kJ mol}^{-1}ΔH∘=+178 kJ mol−1 and ΔS∘=+160 J K−1 mol−1\Delta S^\circ = +160\text{ J K}^{-1}\text{ mol}^{-1}ΔS∘=+160 J K−1 mol−1.
Which statement correctly describes the temperature range in which this reaction is thermodynamically feasible?
The reaction is feasible only at temperatures above 1112.5∘C1112.5^{\circ}\text{C}1112.5∘C.
The reaction is feasible only at temperatures below 839.5∘C839.5^{\circ}\text{C}839.5∘C.
The reaction is feasible only at temperatures above 839.5∘C839.5^{\circ}\text{C}839.5∘C.
The reaction is feasible only at temperatures above 1385.5∘C1385.5^{\circ}\text{C}1385.5∘C.
27 exam-style questions on AQA A Level Chemistry Thermodynamics (A-level only), covering Born–Haber cycles (A-level only) and Gibbs free-energy change, $\Delta G$ , and entropy change, $\Delta S$ (A-level only). Each one has a worked solution and a mark scheme showing where the marks go.