Acetic acid

  4.76

Malic acid, pK₁

  3.40

Acetoacetic acid

  3.58

pK₂

  5.11

Ammonium ion

  9.25

Phenol

  9.89

Ascorbic acid, pK₁

  4.10

Phosphoric acid, pK₁

  2.12

                       pK₂

11.79

                          pK₂

  7.21

Benzoic acid

  4.20

                          pK₃

12.67

n-Butyric acid

  4.81

Pyridinium ion

  5.25

Cacodylic acid

  6.19

Pyrophosphoric acid, pK₁

  0.90

Citric acid, pK₁

  3.14

                                 pK₂

  2.00

                 pK₂

  4.77

                                 pK₃

  6.60

                 pK₃

  6.39

                                 pK₄

  9.40

Ethylammonium ion

10.81

Succinic acid, pK₁

  4.21

Formic acid

  3.75

                      pK₂

  5.64

Glycine, pK₁

  2.35

Trimethylammonium ion

  9.79

             pK₂

  9.78

Tris (hydroxymethyl) aminomethane

  8.08

Imidazolium ion

  6.95

Water*

15.74

Lactic acid

  3.86

Fumaric acid, pK₁

  3.03

                     pK₂

  4.44