Question

Calculate the Gibbs free energy change for the following reaction at 298 K:2CH4(g) + 3O2(g) → 2CO2(g) + 2H2O(g)Given the standard Gibbs free energy of formation at 298 K for CH4(g), O2(g), CO2(g) and H2O(g) are -50.8 kJ/mol, 0 kJ/mol, -394.4 kJ/mol, and -241.8 kJ/mol respectively.

Answer 1

To calculate the Gibbs free energy change  G  for the reaction, we can use the following equation:G =  G products  -  G reactants where G products  is the sum of the standard Gibbs free energy of formation for the products and G reactants  is the sum of the standard Gibbs free energy of formation for the reactants.For the given reaction:2CH4 g  + 3O2 g   2CO2 g  + 2H2O g G products  = [2   -394.4 kJ/mol ] + [2   -241.8 kJ/mol ] = -788.8 kJ/mol - 483.6 kJ/mol = -1272.4 kJ/molG reactants  = [2   -50.8 kJ/mol ] + [3   0 kJ/mol ] = -101.6 kJ/molNow, we can calculate G for the reaction:G =  G products  -  G reactants  = -1272.4 kJ/mol -  -101.6 kJ/mol  = -1170.8 kJ/molSo, the Gibbs free energy change for the reaction at 298 K is -1170.8 kJ/mol.