Question

Consider the following reaction:
CaCO3(s)→CaO(s)+CO2(g).
Estimate ΔG∘ for this reaction at each of the following temperatures. (Assume that ΔH∘ and ΔS∘ do not change too much within the given temperature range.)

Part A

310 K

Part B 1035K Part C 1455K in kJ

Answer 1

ΔH∘   = ΔH∘products - ΔH∘ reactants

         = (-635.1 -393.5) - (-1207)

        = 178.4 kJ /mol

ΔS∘ = ΔS∘products - ΔS∘reactants

         = (39.75 + 213.6)-(88.70)

         = 164.65 J / K

        = 0.16465 kJ / mol

at 310 K

ΔG∘ = ΔH∘ - T ΔS∘

        = 178.4 - 310 x 0.16465

        = 127.4 kJ / mol

at 1035 K

ΔG∘ = ΔH∘ - T ΔS∘

        = 178.4 - 1035 x 0.16465

       = 7.987 kJ / mol

    at 1455 K

ΔG∘ = ΔH∘ - T ΔS∘

        = 178.4 - 1455 x 0.16465

       = - 61.17 kJ / mol