Given reaction:
N2(g) + 3H2(g) → 2NH3(g)
The standard free energy change is given as:
ΔG° = ∑ nΔGf(products) - ∑ nΔGf(reactants)
= [2ΔGf(NH3(g))] - [ΔGf(N2(g)) + 3ΔGf(H2(g))]
= [2(-16.48)] - [ 1(0) + 3(0)] = -32.96 kJ
Ans: Free energy of the reaction is -32.96 kJ, i.e. reaction is spontaneous.