Autoionization
| Formula / Notation | 2H₂O ⇌ H₃O⁺ + OH⁻; Kw = [H⁺][OH⁻] = 1.0×10⁻¹⁴ |
|---|---|
| Also Known As | Autoprotolysis; self-ionisation of water; water self-dissociation; amphiprotic behaviour; Kw equilibrium |
What is Autoionization?
Autoionization (also called autoprotolysis) is the spontaneous transfer of a proton from one molecule to another of the same substance. The most important example is the autoionization of water, in which two water molecules react to form a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). This equilibrium is described by the ion product of water, Kw.
Formula & Notation
Other Names / Synonyms: Autoprotolysis; self-ionisation of water; water self-dissociation; amphiprotic behaviour; Kw equilibrium
Properties & Characteristics
Uses & Applications
Safety Information
Always consult the SDS/MSDS before handling any chemical. This information is for educational purposes only.
Key Facts
Frequently Asked Questions
Autoionization (also called autoprotolysis) is the spontaneous transfer of a proton from one molecule to another of the same substance. The most important example is the autoionization of water, in which two water molecules react to form a hydronium ion (H₃O⁺) and a hydroxide ion (OH⁻). This equilibrium is described by the ion product of water, Kw.
Foundation of pH scale and acid-base chemistry; buffer calculations; titration theory; understanding amphoteric behaviour; biochemical pH regulation
No direct hazard — an equilibrium concept. Water is safe, but strongly acidic or basic conditions resulting from shifted equilibria can be corrosive.
The formula or notation for Autoionization is: 2H₂O ⇌ H₃O⁺ + OH⁻; Kw = [H⁺][OH⁻] = 1.0×10⁻¹⁴