[H+] [A-]
Kb = -------------
[HA]
and pKa = - log Ka
| Acid | Formula | pKa |
|---|---|---|
| Hydriodic | HI | ~-11 |
| Hydrobromic | HBr | ~-9 |
| Perchloric | HClO4 | ~-7 |
| Hydrochloric | HCl | ~-7 |
| Chloric | HClO3 | ~-3 |
| Sulfuric (1) | H2SO4 | ~-2 |
| Nitric | HNO3 | ~-1.3 |
| Hydronium ion | H3O+ | 0.00 |
| Urea acidium ion | NH2CONH3+ | 0.18 |
| Iodic | HIO3 | 0.80 |
| Oxalic (1) | H2C2O4 | 1.23 |
| Sulfurous (1) | H2SO3 | 1.81 |
| Sulfuric (2) | HSO4- | 1.92 |
| Chlorous | HClO2 | 1.96 |
| Phosphoric (1) | H3PO4 | 2.12 |
| Arsenic (1) | H3AsO4 | 2.30 |
| Chloroacetic | CH2ClCOOH | 2.85 |
| Hydrofluoric | HF | 3.18 |
| Nitrous | HNO2 | 3.34 |
| Formic | HCOOH | 3.75 |
| Benzoic | C6H5COOH | 4.19 |
| Oxalic (2) | HC2O4- | 4.19 |
| Hydrazoic | HN3 | 4.72 |
| Acetic | CH3COOH | 4.75 |
| Propionic | CH3CH2COOH | 4.87 |
| Pyridinium ion | HC5H5N+ | 5.25 |
| Carbonic (1) | H2CO3 | 6.37 |
| Sulfurous (2) | HSO3- | 6.91 |
| Arsenic (2) | H2AsO4- | 7.03 |
| Hydrosulfuric | H2S | 7.04 |
| Phosphoric (2) | H2PO4- | 7.21 |
| Hypochlorous | HClO | 7.53 |
| Ammonium ion | NH4+ | 9.25 |
| Hydrocyanic | HCN | 9.21 |
| Carbonic (2) | HCO3- | 10.32 |
| Methylammonium ion | CH3NH3+ | 10.64 |
| Arsenic (3) | HAsO42- | 11.53 |
| Hydrogen peroxide | H2O2 | 11.62 |
| Phosphoric (3) | HPO42- | 12.67 |
| Water | H2O | 14.00 |