What is Le Châtelier's principle?
Solution: Here, we are going to discuss about Le Chatelier’s principle.
Le Chatelier’s principle states that, a change in any of the factors that determine the equilibrium conditions of a system will cause the system to change in such a manner so as to reduce or to counteract the effect of the change. This is applicable to all physical and chemical equilibria.
It is used in order to decide what course the reaction adopts and make a qualitative prediction about the effect of a change in conditions on equilibrium.
Let us consider the reaction,
H2(g) + I2(g) ⇄ 2HI(g)
If H2 is added to the reaction mixture at equilibrium, then the equilibrium of the reaction is disturbed. In order to restore it, the reaction proceeds in a direction wherein H2 is consumed, i.e., more of H2 and I2 react to form HI and finally the equilibrium shifts in right(forward) direction. This is in accordance with the Le Chatelier’s principle which implies that in case of addition of a reactant/product, a new equilibrium will be set up in which the concentration of the reactant / product should be less than what it was after the addition but more than what it was in the original mixture.