basic

Brønsted Conjugate Pair Calculator

pKb of conjugate base from acid pKa (and vice-versa).

For an acid–conjugate-base pair in water at 25 °C, compute the pKb of the conjugate base from the acid pKa using pKa + pKb = 14, and report the corresponding Ka and Kb.

Dr. Helena Ortiz By Dr. Helena Ortiz
Published Last reviewed 1 min read

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How to use this calculator

  1. Fill in the inputs above using the units you already have.
  2. Values update automatically as you type — no submit button needed.
  3. Hover any result row for the underlying formula and intermediate values.

Formula

pKb = 14 − pKa; Ka = 10^(−pKa); Kb = 10^(−pKb).

In depth

For an acid–conjugate-base pair in water at 25 °C, compute the pKb of the conjugate base from the acid pKa using pKa + pKb = 14, and report the corresponding Ka and Kb.