Standard molar Gibbs free energies of formation (ΔG°_f) at 298 K are listed below:
N₂(g) 0 kJ·mol⁻¹
H₂(g) 0 kJ·mol⁻¹
NH₃(g) −16.4 kJ·mol⁻¹
Consider the reaction carried out at 298 K and 1 bar total pressure:
N₂(g) + 3 H₂(g) ⇌ 2 NH₃(g)
The universal gas constant is R = 8.314 J·mol⁻¹·K⁻¹.
(a) Calculate the standard Gibbs free-energy change ΔG° for the reaction.
(b) Determine the numerical value of the equilibrium constant K at 298 K.
(c) Explain how the magnitude of K you obtained in part (b) accounts for the industrial need to employ high pressure when synthesizing ammonia.
(d) If the temperature is increased while ΔH° remains roughly constant and negative, predict qualitatively how K will change and discuss the impact on ammonia yield.