Question

State and explain Le Chatelier’s principle suitably with reference to change in concentration.

Answer 1

Le Chatelier’s Principle:

When a system at equilibrium is subjected to a change in any of the factors determining the equilibrium conditions of a system, the system will respond in such a way as to minimize the effect of change.

Change in concentration:

1. Consider reversible reaction representing the production of ammonia (NH₃).
   \[\ce{N_{2(g)} + 3H_{2(g)} ⇌ 2NH_{3(g)} + Heat}\]
2. According to Le Chatelier's principle, when H₂ or N₂ is added to equilibrium, the effect of the addition of H₂ or N₂ or is reduced by shifting the equilibrium from left to right so that the added N₂ or H₂ is consumed.
3. The forward reaction occurs to a large extent than the reverse reaction until the new equilibrium is established. As a result, the yield of NH₃ is increased.
4. In general, if the concentration of one of the species in equilibrium mixture is increased, the position of equilibrium shifts in the opposite so as to reduce the concentration of this species. However, the equilibrium constant remains unchanged.