Question

Estimate the value of the equilibrium constant at 530 K for each of the following reactions. 2H2S(g)⇌2H2(g)+S2(g)

Answer 1

2H2S(g)   <--------------> 2 H2 (g) + S2 (g)

ΔH∘rxn = ΔH∘f products - ΔH∘f reactants

            = 129 - (2 x - 20.6)

           = 170.2 kJ/mol

ΔSorxn = 2 x 130.7 + 228.1 - (2 x 205.7)

            = 78.1 J/K

ΔGo = ΔH∘ - T ΔSo

        = 170.2 - 530 x (- 0.0781)

        = 211.6 kJ/mol

ΔGo = - RT ln K

211.6 = - 8.314 x 10^-3 x 530 x ln K

K = 1.40 x 10^-21

Equilibrium constant K = 1.40 x 10^-21