Effect of conditions on KEdexcel A-Level Chemistry: Mind map

Exam questions on Effect of conditions on K

1. The Haber process makes ammonia: N₂(g) + 3H₂(g) ⇌ 2NH₃(g), ΔH = −92 kJ mol⁻¹. A chemical engineer studies how the equilibrium constant Kp, and the composition of the equilibrium mixture, change when the conditions are altered.
   The iron catalyst is added to the reactor. Explain why this does not change the value of Kp.2 marks
2. Hydrogen is made on a large scale by steam reforming of methane: CH₄(g) + H₂O(g) ⇌ CO(g) + 3H₂(g), ΔH = +206 kJ mol⁻¹. The reformers run at about 1100 K.
   Explain why the percentage of hydrogen in the equilibrium mixture is higher at 1100 K than at 900 K.2 marks
3. In hydrogen plants carbon monoxide reacts with steam in the water–gas shift reaction: CO(g) + H₂O(g) ⇌ CO₂(g) + H₂(g), ΔH = −41 kJ mol⁻¹. A first reactor runs at about 650 K and a second reactor at about 470 K.
   Explain the effect on Kp, and on the position of equilibrium and the yield of hydrogen, of lowering the temperature from 650 K to 470 K.3 marks