Chemistry – Physical chemistry | e-Consult

(a) To maximise the yield of ammonia, the Haber process is carried out at a high temperature (typically 400-450 °C) and high pressure (typically 200-300 atmospheres). A high temperature favours the forward reaction (exothermic), and a high pressure favours the side with fewer moles of gas (the product side).

(b) Increasing the pressure favours the side of the reaction with fewer moles of gas. In this case, the product side has 2 moles of NH₃ and the reactant side has 4 moles of gas (2 of N₂ and 2 of H₂). Therefore, increasing the pressure shifts the equilibrium to the right, favouring the formation of ammonia.

(c) Increasing the temperature will shift the equilibrium to the left, favouring the reverse reaction (decomposition of ammonia into nitrogen and hydrogen). This will decrease the yield of ammonia.