Donnan equilibrium

chemistry

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June 17, 2026

Quick Summary

The Donnan equilibrium describes the distribution of ions across a semipermeable membrane when at least one ion cannot pass through. This occurs when two solutions with different concentrations of electrolytes are separated by a membrane that allows some ions to pass but not others.1

The movement of permeable ions creates a difference in electrical potential across the membrane. This phenomenon is crucial in biological systems, such as in the nervous system, where ion distribution across nerve cell membranes generates electrical signals. Frederick George Donnan, a British chemist, first studied and measured these effects in 1911, leading to the equilibrium being named after him.21

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Frederick George Donnan
…have both become associated with Donnan’s name.
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…have both become associated with Donnan’s name.
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nervous system
Ions
This is known as the Donnan equilibrium, after Frederick George Donnan, a British chemist who, in 1911, first measured the changes brought about by adding an impermeant substance to one side of a divided solution at equilibrium.
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This is known as the Donnan equilibrium, after Frederick George Donnan, a British chemist who, in 1911, first measured the changes brought about by adding an impermeant substance to one side of a divided solution at equilibrium.
Read More