For a chemical reaction, the equilibrium constant can be defined as the ratio between the amount of reactant and the amount of product that is used to determine chemical behaviour.
At equilibrium, Rate of the forward reaction = Rate of the backward reaction
i.e. rf = rb Or, kf × α × [A]a[B]b = kb × α × [C]c [D]d
Factors that affect the equillibrium
Listed below are factors that affect the equilibrium:
- Change in concentration of any product or reactant.
The concentration of reactants or products removed is released by the reaction which is in the direction that replenishes the substance which is removed. When the concentration of the reactant or product is changed, there is a change in the composition of the mixture in chemical equilibrium.
- Change in the pressure of the system.
Change in pressure occurs due to the change in the volume. If there is a change in pressure it can transform the gaseous reaction as the total number of gaseous reactants and products are now different.
- Change in temperature of the system.
The change in temperature affects the equilibrium constant, and also the rate of reaction is also affected by the change in temperature. As temperature increases the equilibrium constant of an exothermic reaction decreases.
In an endothermic reaction the equilibrium constant increases with an increase in temperature.