Representation of the Equilibrium Constant

For a balanced reaction of the type,

aA + bB ⇌  cC + dD

According to the law of mass action, the constant value obtained by relating equilibrium concentrations of reactants and products is called the equilibrium constant. For the forward reaction, this is given by��=[�]�[�]�[�]�[�]�

The equilibrium constant for the reverse reaction is the inverse of the forward reaction and is given by:��′=1��=[�]�[�]�[�]�[�]�

If the coefficients of the chemical equation are multiplied by a factor ‘n’ then the equilibrium constant is raised by the power ‘n’ i.e. the constant becomes K_cⁿ.

Relation between K_c, K_p and K_x

K_p  = K_x . P Δng

K_c is the equilibrium constant expressed in terms of the concentration of the reactants/products. Similarly, K_p is the constant in terms of the partial pressures of the substances and K _x is expressed in terms of the mole fraction.