Donnan's equilibrium

Donnan's equilibrium

the state of equilibrium that exists at a semipermeable membrane when it separates two solutions containing electrolytes, the ions of some of which are able to permeate the membrane and the others not. The distribution of the ions in the two solutions becomes complicated so that an electrical potential develops between the two sides of the membrane and the two solutions have different osmotic pressures. Called also Gibbs-Donnan phenomenon.