## Wikipedia - Properties of water (en) Wikipedia - Self-ionization of water (en) Wikipedia - Tính chất của nước (vi) 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 @[email protected] For solvents in which no other @[email protected] processes are significant the term is synonymous with 'ionic product'. The @[email protected] 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]