Short-range forces in surface and bubble interaction

We discuss two examples where short-range forces in electrolytes have a large effect on interfacial phenomena. In case of charged surfaces, short-range forces lead to a compact Stern layer that lowers apparent surface potential and at short surface separations results in the ‘hydration force’. For free surfaces in electrolytes, the surface affinities of different anions and cations lead to the combination rules that determine the propensity for bubble coalescence in salty water.