In the equilibrium constant expression, the concentrations of pure solids and pure liquids are not included because their concentrations are considered to be constant and do not affect the reaction quotient. This is because the concentration of a pure solid or liquid does not change with the addition or removal of another reactant or product. Therefore, they are not considered when calculating the equilibrium constant expression. Only the concentrations of aqueous or gaseous reactants and products are included in the expression.
~~~Harsha~~~