Exemplar Problems

Problem 12 : For the reaction N₂(g) + 3H₂(g) ⇌ 2NH₃(g), the equilibrium constant Kc is 4.84 x 10⁻³ at 298 K. Calculate the standard Gibbs free energy change (∆G°) at this temperature. (R = 8.314 J/(mol•K))

Solution :

The relationship between ∆G° and Kc is given by the equation: ∆G° = -RT ln(Kc)

∆G° = -8.314 J/(mol•K) * 298 K * ln(4.84 x 10⁻³)

∆G° ≈ -8.314 J/(mol•K) * 298 K * (-5.330)

∆G° ≈ 12,573.45 J/mol ≈ 12.57 kJ/mol

So, the standard Gibbs free energy change (∆G°) for the reaction at 298 K is approximately 12.57 kJ/mol.