Once again, the concentration does not appear in the equilibrium constant expression.. The larger the Kb, the stronger the base and the higher the OH− concentration at equilibrium. In this c...Once again, the concentration does not appear in the equilibrium constant expression.. The larger the Kb, the stronger the base and the higher the OH− concentration at equilibrium. In this case, the sum of the reactions described by Ka and Kb is the equation for the autoionization of water, and the product of the two equilibrium constants is Kw: