In the conversion of lime stone to lime, CaCO3(s) → CaO(s) + CaO2(g) the values of ΔH∘ and ΔS∘ are +179.1 kJ mol−1 ad 160.2 JK−1 mol−1 respectively at 298 K and 1 bar. Assuming, ΔH∘ and ΔS∘ do not change with temperature; temperature above which conversion of lime stone to lime will be spontaneous is
1118 K
ΔG∘ = ΔH∘ − TΔS∘
At equilibrium ΔG∘ = 0
ΔH∘ = TΔS∘
T = 179.1 × 1000160.2 = 1118K
So, at the temperature above 118K, the reaction will becomes spontaneous.