Question

What is the standard Gibbs free energy change (in kJ/mol) for the reaction 2H2O (l) -> 2H2 (g) + O2 (g) at 298 K, given that the enthalpy change (ΔH) for the reaction is -483.60 kJ/mol and the entropy change (ΔS) for the reaction is 69.91 J/mol.K?

Answer 1

To calculate the standard Gibbs free energy change  G  for the reaction, we can use the following equation:G = H - TSwhere H is the enthalpy change, T is the temperature in Kelvin, and S is the entropy change.Given values:H = -483.60 kJ/molS = 69.91 J/mol.KT = 298 KFirst, we need to convert the entropy change from J/mol.K to kJ/mol.K:S = 69.91 J/mol.K *  1 kJ / 1000 J  = 0.06991 kJ/mol.KNow we can plug the values into the equation:G =  -483.60 kJ/mol  -  298 K * 0.06991 kJ/mol.K G = -483.60 kJ/mol - 20.81 kJ/molG = -504.41 kJ/molThe standard Gibbs free energy change for the reaction is -504.41 kJ/mol.