Chemical Equilibria

Equilibrium can only be reached in a closed system where the reactants and products cannot escape.Equilibrium is a dynamic process but the macroscopic properties (e.g. concentrations) of the system do not change with time. Equilibrium can be approached in either direction.In the reaction:A + B ⇌ C + DInitially there is only A and B present.As the reaction proceeds, the rate of the forward reaction decreases as the reactants are used up.As more products are formed, the rate of the reverse reaction increases.Eventually, the rate of the forward reaction is equal to the rate of the reverse reaction and an equilibrium is reachedThe point at which the rate of the forward reaction is equal to the reverse reaction determines the position of equilibrium. The relative proportions of products and reactants become constant.