Question

Use Le Châtelier’s principle to predict what will happen to the following equilibrium if the pressure is decreased.
2NH3(g)  N2(g) + 3H2(g)

Answer 1

Decrease in pressure (increase in volume) favors the side with more gas molecules. Here the forward side produces 4 moles of gas (1 N2 + 3 H2) vs 2 moles on the left (2 NH3), so the equilibrium shifts to the right (toward products). NH3 concentration/partial pressure falls while N2 and H2 rise. (Kp and Kc are unchanged at constant temperature.)