Work out pka and pkb instantly with clear inputs, formula shown and shareable results.
pKa is the negative logarithm of Ka, and an acid and its conjugate base are locked together by Ka x Kb = Kw, which in logarithmic form is pKa + pKb = pKw. Acetic acid with Ka = 1.8e-5 has pKa 4.74, so its conjugate base has pKb 9.26 at 25 C.
Logarithmic constants
pKa = -log10(Ka), pKb = -log10(Kb)
Conjugate pair relation
pKa + pKb = pKw (14.00 at 25 C)
Yes. A lower pKa means a larger Ka and more complete dissociation, so strong acids sit at negative pKa values.
Because the 14.00 figure only holds at 25 C. Changing Kw changes the pKa-pKb sum, and the calculator makes that explicit.