The acid dissociation constant (K_{a}) and base dissociation constant (K_{b}) values represent how easily an acid or base dissociates into ions, in a solution.

Strong acids and strong bases fully dissociate. They possess a K_{a} > 1, meaning that dissociation is carried out completely. There is no mix of undissociated molecules and ions at equilibrium, only ions.

Weak acids have a K_{a} < 1. At equilibrium, in solution, there is a mixture of complete molecules and dissociated ions. ICE tables can be used to calculate ratios of reactants and products at equilibrium.

**Formulae**

For acid and its conjugate base, or a base and its conjugate acid:

K_{w} = K_{a} x K_{b}

Where K_{w} is the ion constant for water.

**Polyprotic acids and bases**

These species can donate or receive more than one proton, e.g. sulfuric acid. The second dissociation constant is usually extremely low.

**pK _{a} and pK_{b}**

K_{a} and K_{b} can be converted into easier forms to work with, by finding their inverse logs.

pK_{a} is the inverse log of K_{a}. The formula is -log[K_{a}]

pK_{b} is the inverse log of K_{b}. The formula is -log[K_{b}]