Calculate the base dissociation constant from concentration and measured pH.
K_b mirrors K_a using hydroxide rather than hydrogen ion concentration. The conjugate relationship means knowing one member of an acid-base pair fixes the other completely. Tabulated data usually gives pK_a even for bases, so the conjugate conversion is needed constantly in practice.
Kb
K_b = [OH⁻]² ÷ (C − [OH⁻]); pK_a + pK_b = 14 for a conjugate pair
K_b = [OH⁻]² ÷ (C − [OH⁻]); pK_a + pK_b = 14 for a conjugate pair K_b mirrors K_a using hydroxide rather than hydrogen ion concentration. The conjugate relationship means knowing one member of an acid-base pair fixes the other completely.
Tabulated data usually gives pK_a even for bases, so the conjugate conversion is needed constantly in practice.
This calculator takes 2 inputs: Initial base concentration, Measured pH. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.