Acid-Base / pH Tools
pKa/pKb reference for 31 acids and 14 bases, buffer pH calculator, and titration curve simulator.
Acids (pKa)
| Name | Formula | pKa | Type | Conjugate Base |
|---|
| Hydrochloric acid | HCl | -6.30 | strong acid | Cl⁻ |
| Hydrobromic acid | HBr | -9.00 | strong acid | Br⁻ |
| Hydroiodic acid | HI | -9.30 | strong acid | I⁻ |
| Sulfuric acid | H₂SO₄ | -3.00, 1.99 | strong acid | HSO₄⁻ / SO₄²⁻ |
| Nitric acid | HNO₃ | -1.40 | strong acid | NO₃⁻ |
| Perchloric acid | HClO₄ | -10.00 | strong acid | ClO₄⁻ |
| Hydrofluoric acid | HF | 3.17 | weak acid | F⁻ |
| Acetic acid | CH₃COOH | 4.76 | weak acid | CH₃COO⁻ |
| Formic acid | HCOOH | 3.75 | weak acid | HCOO⁻ |
| Benzoic acid | C₆H₅COOH | 4.20 | weak acid | C₆H₅COO⁻ |
| Carbonic acid | H₂CO₃ | 6.35, 10.33 | weak acid | HCO₃⁻ / CO₃²⁻ |
| Phosphoric acid | H₃PO₄ | 2.15, 7.20, 12.37 | weak acid | H₂PO₄⁻ / HPO₄²⁻ / PO₄³⁻ |
| Citric acid | C₆H₈O₇ | 3.13, 4.76, 6.40 | weak acid | citrate ions |
| Oxalic acid | H₂C₂O₄ | 1.25, 4.27 | weak acid | HC₂O₄⁻ / C₂O₄²⁻ |
| Lactic acid | CH₃CH(OH)COOH | 3.86 | weak acid | lactate |
| Ascorbic acid (Vitamin C) | C₆H₈O₆ | 4.17, 11.60 | weak acid | ascorbate |
| Hypochlorous acid | HOCl | 7.53 | weak acid | OCl⁻ |
| Boric acid | H₃BO₃ | 9.24 | weak acid | B(OH)₄⁻ |
| Hydrogen sulfide | H₂S | 7.00, 17.00 | weak acid | HS⁻ / S²⁻ |
| Hydrogen cyanide | HCN | 9.21 | weak acid | CN⁻ |
| Ammonium ion | NH₄⁺ | 9.25 | weak acid | NH₃ |
| Phenol | C₆H₅OH | 9.95 | weak acid | C₆H₅O⁻ |
| Water | H₂O | 15.74 | weak acid | OH⁻ |
| Ethanol | C₂H₅OH | 15.90 | weak acid | C₂H₅O⁻ |
| Methanol | CH₃OH | 15.50 | weak acid | CH₃O⁻ |
| Sulfurous acid | H₂SO₃ | 1.81, 6.91 | weak acid | HSO₃⁻ / SO₃²⁻ |
| Chromic acid | H₂CrO₄ | -0.98, 6.50 | weak acid | HCrO₄⁻ / CrO₄²⁻ |
| Nitrous acid | HNO₂ | 3.25 | weak acid | NO₂⁻ |
| Chlorous acid | HClO₂ | 1.94 | weak acid | ClO₂⁻ |
| Glycine | NH₂CH₂COOH | 2.34, 9.60 | amino acid | glycinate |
| Alanine | CH₃CH(NH₂)COOH | 2.35, 9.87 | amino acid | alaninate |
Bases (pKb)
| Name | Formula | pKb | Type |
|---|
| Sodium hydroxide | NaOH | -0.56 | strong base |
| Potassium hydroxide | KOH | -0.70 | strong base |
| Calcium hydroxide | Ca(OH)₂ | -2.37 | strong base |
| Barium hydroxide | Ba(OH)₂ | -1.11 | strong base |
| Ammonia | NH₃ | 4.75 | weak base |
| Methylamine | CH₃NH₂ | 3.36 | weak base |
| Dimethylamine | (CH₃)₂NH | 3.27 | weak base |
| Trimethylamine | (CH₃)₃N | 4.19 | weak base |
| Ethylamine | C₂H₅NH₂ | 3.37 | weak base |
| Aniline | C₆H₅NH₂ | 9.37 | weak base |
| Pyridine | C₅H₅N | 8.77 | weak base |
| Hydrazine | N₂H₄ | 5.89 | weak base |
| Sodium carbonate | Na₂CO₃ | 3.67 | weak base |
| Sodium bicarbonate | NaHCO₃ | 7.65 | weak base |