Expression for Equilibrium constant ( K ) The active mass of a pure solid is constant irrespective of its amount and if a pure liquid is present in excess, its active mass is also constant.In both the cases we put active mass equal to 1. Molar concentration of a substance means mol L-1 of the substance which is obtained by dividing the amount of the substance in moles by … [Read more...] about Expression and Units Of Equilibrium Constant