Dissociation constant of weak electrolytes

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Dissociation constants of weak electrolytes (approximate concentrations: 0.01–0.003 mol·L⁻¹, temperature: 298 K)
Name | Chemical formula | Dissociation constant, Kp
Acetic acid | HAc | 1.76×10⁻⁵ | 4.75
Carbonic acid | H₂CO₃ | K₁=4.30×10⁻⁷ | 6.37; K₂=5.61×10⁻¹¹ | 10.25
Oxalic acid | H₂C₂O₄ | K₁=5.90×10⁻² | 1.23; K₂=6.40×10⁻⁵ | 4.19
Nitrous acid | HNO₂ | 4.6×10⁻⁴ (285.5 K) | 3.37
Phosphoric acid | H₃PO₄ | K₁=7.52×10⁻³ | 2.12; K₂=6.23×10⁻⁸ | 7.21; K₃=2.2×10⁻¹³ (291 K) | 12.67
Sulfurous acid | H₂SO₃ | K₁=1.54×10⁻² (291 K) | 1.81; K₂=1.02×10⁻⁷ | 6.91
Sulfuric acid | H₂SO₄ | K₂=1.20×10⁻² | 1.92
Hydrogen sulfide | H₂S | K₁=9.1×10⁻⁸ (291 K) | 7.04; K₂=1.1×10⁻¹² | 11.96
Hydrocyanic acid | HCN | 4.93×10⁻¹⁰ | 9.31
Chromic acid | H₂CrO₄ | K₁=1.8×10⁻¹⁰ | 10.74; K₂=3.20×10⁻⁷ | 6.49
*Boric acid* | H₃BO₃ | 5.8×10⁻¹⁰ | 9.24
Hydrofluoric acid | HF | 3.53×10⁻⁴ | 3.45
Hydrogen peroxide | H₂O₂ | 2.4×10⁻¹² | 11.62
Hypochlorous acid | HClO | 2.95×10⁻⁵ (291 K) | 4.53
Hypobromous acid | HBrO | 2.06×10⁻⁹ | 8.69
Hypoiodous acid | HIO | 2.3×10⁻¹¹ | 10.64
Iodic acid | HIO₃ | 1.69×10⁻¹⁰ | 10.77
Arsenic acid | H₃AsO₄ | K₁=5.62×10⁻³ (291 K) | 2.25; K₂=1.70×10⁻⁷ | 6.77; K₃=3.95×10⁻¹² | 11.40
Arsenious acid | HAsO₂ | 6×10⁻¹⁰ | 9.22
Ammonium ion | NH₄⁺ | 5.56×10⁻¹⁰ | 9.25
Ammonia solution | NH₃·H₂O | 1.79×10⁻⁵ | 4.75
Hydrazine | N₂H₄ | 8.91×10⁻⁷ | 6.05
Hydroxylamine | NH₂OH | 9.12×10⁻⁹ | 8.04
Lead hydroxide | Pb(OH)₂ | 9.6×10⁻⁴ | 3.02
Lithium hydroxide | LiOH | 6.31×10⁻¹⁰ | 10.2
Beryllium hydroxide | Be(OH)₂ | 1.78×10⁻⁶ | 5.75; BeOH⁺=2.51×10⁻⁹ | 8.6
Aluminum hydroxide | Al(OH)₃ | 5.01×10⁻⁹ | 8.3; Al(OH)₂⁺=1.99×10⁻¹⁰ | 9.7
Zinc hydroxide | Zn(OH)₂ | 7.94×10⁻⁷ | 6.1
Cadmium hydroxide | Cd(OH)₂ | 5.01×10⁻¹¹ | 10.3
*Ethylenediamine* | H₂NC₂H₄NH₂ | K₁=8.5×10⁻⁵ | 4.07; K₂=7.1×10⁻⁸ | 7.15
*Hexamethylenetetramine* | (CH₂)₆N₄ | 1.35×10⁻⁹ | 8.87
*Urea* | CO(NH₂)₂ | 1.3×10⁻¹⁴ | 13.89
*Protonated hexamethylenetetramine* | (CH₂)₆N₄H⁺ | 7.1×10⁻⁶ | 5.15
Formic acid | HCOOH | 1.77×10⁻⁴ (293 K) | 3.75
Chloroacetic acid | ClCH₂COOH | 1.40×10⁻³ | 2.85
Glycine | NH₂CH₂COOH | 1.67×10⁻¹⁰ | 9.78
*Phthalic acid* | C₆H₄(COOH)₂ | K₁=1.12×10⁻³ | 2.95; K₂=3.91×10⁻⁶ | 5.41
Citric acid | (HOOCCH₂)₂C(OH)COOH | K₁=7.1×10⁻⁴ | 3.14; K₂=1.68×10⁻⁵ (293 K) | 4.77; K₃=4.1×10⁻⁷ | 6.39
*α-Tartaric acid* | (CH(OH)COOH)₂ | K₁=1.04×10⁻³ | 2.98; K₂=4.55×10⁻⁵ | 4.34
*8-Hydroxyquinoline* | C₉H₆NOH | K₁=8×10⁻⁶ | 5.1; K₂=1×10⁻⁹ | 10.0
Phenol | C₆H₅OH | 1.28×10⁻¹⁰ (293 K) | 9.89
*p-Aminobenzenesulfonic acid* | H₂NC₆H₄SO₃H | K₁=2.6×10⁻¹⁰ | 10.58; K₂=7.6×10⁻⁴ | 3.12
*Ethylenediaminetetraacetic acid (EDTA)* | (CH₂COOH)₂NH⁺CH₂CH₂NH⁺(CH₂COOH)₂ | K₅=5.4×10⁻⁷ | 6.27; K₆=1.12×10⁻¹¹ | 10.95