For a gaseous reaction, standard conditions are 298 K and a partial pressure of 1 bar for all species. For the reaction N_2 (g) + 3H_2 (g) 2NH_3 (g) the standard change in Gibbs free energy is Delta G degree = -72.6 kJ/mol. What is Delta G for this reaction at 298 K when the partial pressures are P_N_1 =0.500 bar, P_H_2 =0.250 bar, and P_NH_3 = 0.800 bar