Thermodynamics

 

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

       H2(g) + F2(g)   2HF(g)

 

       (a) ΔG°rxn = ΣΔGf°(products) - ΣΔGf°(reactants)

             ΔG°rxn = [2ΔGf°(HF(g))] - [ΔGf°(H2(g)) + ΔGf°(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 = PHF2/(PH2 x PF2)

            ΔG = ΔG° + R x T x ln(PHF2/(PH2 x PF2))

            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