Thermodynamics

 64) T = 298 K          R = 8.314 J/mol•K

       H₂(g) + F₂(g)   2HF(g)

       (a) ΔG°_rxn = ΣΔG_f°(products) - ΣΔG_f°(reactants)

             ΔG°_rxn = [2ΔG_f°(HF(g))] - [ΔG_f°(H₂(g)) + ΔG_f°(F₂(g))]

             ΔG°_rxn = [2 mol HF(g) x -270.70 kJ/1 mol HF(g)] - 0 = -541.4 kJ/mol

       (b) ΔG = ΔG° + RTlnQ

             Q = P_HF²/(P_H2 x P_F2)

            ΔG = ΔG° + R x T x ln(P_HF²/(P_H2 x P_F2))

            ΔG = -541.4 kJ/mol + 8.314 J/mol•K x 298 K x 1 kJ/10³ J x ln(0.36²/(8.0 x 4.51)) = -553.3 kJ/mol