Ionic product of water
Water undergoes self-dissociation, also referred to as self-ionization or autodissociation. Water ionises into H+ and OH- ions.
- H2O H+ + OH-
The equilibrium constant for the self-dissociation of water is known as ion product for water. Ion product for water is also known as ionization constant, dissociation constant, self-ionization constant. Ionic product of water is symbolized by Kw. Ionic product is calculated as the product of molar concentrations of H+ and OH- ions. Ionic product of water increases with increase in temperature.
- Kw = [H+][OH-]
The value of Kw is 1.00 x 10-14 (mol/L)2 at 25°C. In neutral solutions [H+] = [OH-] [H+] = 10-7 M [H+] = 10-7 M