Consider the following reaction:

N2 (g) + 3H2 (g) 2NH3 (g)

Determine the standard free energy of the the reaction at298K?

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.