Hydrolysis Constant
The equilibrium constant for the hydrolysis of a salt ion in water.
Formula / equation
Kh = Kw / Ka (anion)
Unit
mol/L
In depth
The constant is obtained by dividing the ionic product of water by the dissociation constant of the parent weak acid or base, so the weaker the parent, the greater the hydrolysis. For a salt of a weak acid and weak base, Kh is Kw divided by the product of both constants.
Examples in the real world
Sodium cyanide has Kh = 10⁻¹⁴ / (6.2 × 10⁻¹⁰) = 1.6 × 10⁻⁵, giving a strongly alkaline solution.