Donnan equilibrium

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Related to Donnan equilibrium: Nernst equation

Don·nan e·qui·lib·ri·um

when a semipermeable membrane or its equivalent (for example, a solid ion exchanger) separates a nondiffusible substance, such as protein, from diffusible substances, the diffusible anions and cations are distributed on the two sides of the membrane so that 1) the products of their concentrations are equal, and 2) the sum of the diffusible and nondiffusible anions on either side of the membrane is equal to the sum of the concentrations of diffusible and nondiffusible cations; the unequal distribution of diffusible ions thus produced creates a potential difference across the membrane (membrane potential).
[Frederick G. Donnan]

Donnan equilibrium

[Frederick G. Donnan, Brit. chemist, 1871–1956]
A condition in which an equilibrium is established between two solutions separated by a semipermeable membrane so that the sum of the anions and cations on one side is equal to that on the other side.

Donnan equilibrium

an electromechanical equilibrium that is set up when two solutions are separated by a membrane that is impermeable to some of the ions in solution.


Frederick G., English physical chemist, 1870-1956.
Donnan equilibrium - the equilibrium of small ions between a solution with charged macromolecules, and one without. Synonym(s): Gibbs-Donnan equilibrium
Gibbs-Donnan equilibrium - Synonym(s): Donnan equilibrium