Molecular autoionization

In chemistry, molecular autoionization (or self-ionization) is a chemical reaction between molecules of the same substance to produce ions.

If a pure liquid partially dissociates into ions, it is said to be self-ionizing.

[1]: 163  In most cases the oxidation number on all atoms in such a reaction remains unchanged.

Protic solvents often undergo some autoionization (in this case autoprotolysis):

Protic solvents, mentioned previously, use hydrogen for this role.

Structure of solid phosphorus pentachloride , illustrating its autoionization into PCl + 4 and PCl − 6 . [ 2 ]