autoprotolysis constant

https://doi.org/10.1351/goldbook.A00532
The product of the activities (or, more approximately, concentrations) of the species produced as the result of @A00531@. For solvents in which no other @I03183@ processes are significant the term is synonymous with 'ionic product'. The @A00531@ constant for water, \(K_{\text{w}}\), is equal to the product of activities: \[a\left(\text{H}_{3}\text{O}^{\text{+}}\right)\ a\left(\text{OH}^{\text{-}}\right) = 1.0\times 10^{-14}\] at \(25\ ^{\,\unicode{x26ac}}\text{C}\).
Source:
PAC, 1994, 66, 1077. (Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)) on page 1087 [Terms] [Paper]