Ionization Constants of Aqueous Monoprotic Acids

James Richard Fromm


Common Name Formula Constant pKa
Acetic Acid CH3COOH 1.75 x 10-5 4.756
Ammonium Ion NH4+ 5.60 x 10-10 9.252
Anilinium Ion C6H5NH3+ 2.54 x 10-5 4.596
Benzoic Acid C6H5COOH 6.31 x 10-5 4.200
Chloroacetic Acid CH2ClCOOH 1.36 x 10-3 2.866
Cyanic Acid HOCN 3.54 x 10-4 3.451
Dichloroacetic Acid CHCl2COOH 5.68 x 10-2 1.246
Dimethylammonium Ion (H3C)2NH2+ 1.82 x 10-11 10.739
Ethanol CH3CH2OH 1.31 x 10-14 13.882
Formic Acid HCOOH 1.86 x 10-4 3.732
Hydrazoic Acid HN3 2.37 x 10-5 4.625
Hydrazinium Ion H2NNH3+ 1.03 x 10-8 7.989
Hydrochloric Acid HCl Greater than 1 Negative
Hydrocyanic Acid HCN 5.85 x 10-10 9.233
Hydrofluoric Acid HF 6.94 x 10-4 3.159
Hydroxylammonium Ion HONH3+ 1.12 x 10-6 5.951
Hypochlorous Acid HClO 2.81 x 10-8 7.551
Imidazolium Ion C3H3NNH2+ 1.02 x 10-7 6.992
Lactic Acid H3CCHOHCOOH 1.37 x 10-4 3.863
Methylammonium Ion H3CNH3+ 2.39 x 10-11 10.622
Ethanolammonium Ion HOCH2CH2NH3+ 3.17 x 10-10 9.499
Nitric Acid HNO3 27.79 -1.444
Nitrous Acid HNO2 5.98 x 10-4 3.224
Perchloric Acid HClO4 38.29 -1.583
Phenol C6H5OH 1.08 x 10-10 9.968
Pyridinium Ion C5H5NH+ 6.80 x 10-6 5.167
Trimethylammonium Ion (H3C)3NH+ 1.72 x 10-10 9.763
Water H2O 1.01 x 10-14 13.994

Polyprotic Acids Table

Main Tables

Auxiliary Tables


Copyright 1997 James R. Fromm