Ionization Constants

Acids
Acid Formula Ionization Constant Ka
Acetic CH3COOH 1.8×10–5
Arsenic H3AsO4 5.5×10–3
Benzoic C6H5COOH 6.3×10–5
Boric H3BO3 5.4×10–10
Butanoic C3H7COOH 1.5×10–5
Carbonic H2CO3 Ka1 = 4.5×10–7
Ka2 = 4.7×10–11
Chloroacetic ClCH2COOH 1.4×10–3
Chlorous HClO2 1.1×10–2
Chromic H2CrO4 Ka1 = 1.8×10–1
Ka2 = 3.2×10–7
Cyanic HCNO 3.5×10–4
Formic HCOOH
1.8×10–4
Hydrazoic HN3 2.5×10–5
Hydrocyanic HCN 6.2×10–10
Hydrofluoric HF 6.3×10–4
Hydrogen peroxide H2O2 2.4×10–12
Hydrosulfuric H2S Ka1 = 8.9×10–8
Ka2 = 1.0×10–19
Hypobromous HBrO 2.8×10–9
Hypochlorous HClO 4.0×10–8
Hypoiodous HIO 3.2×10–11
Iodic HIO3 1.7×10–1
Nitrous HNO2 5.6×10–4
Oxalic C2H2O4 Ka1 = 5.6×10–2
Ka2 = 1.5×10–4
Paraperiodic H5IO6 2.8×10–2
Pentanoic C4H9COOH 1.5×10–5
Periodic HIO4 7.3×10–2
Phenol HC6H5O 1.3×10–10
Phosphoric H3PO4 Ka1 = 6.9×10–3
Ka2 = 6.2×10–8
Ka3 = 4.8×10–13
Phosphorous H3PO3 Ka1 = 5.0×10–2
Ka2 = 2.0×10–7
Propanoic C2H5COOH  1.3×10–5
Sulfuric H2SO4 Ka1 = very large
Ka2 = 1.2×10–2
Sulfurous  H2SO3 Ka1 = 1.4×10–2
Ka2 = 6.3×10–8
Trichloroacetic Cl3CCOOH 2.2×10–1





Reference: CRC Handbook of Chemistry and Physics, 2007
Bases
Base Formula Ionization Constant Kb
Ammonia
NH3
1.8×10–5
Methylamine CH3NH2 5.0×10–4
Dimethylamine (CH3)2NH 5.4×10–4
Diethylamine (C2H5)2NH 6.9×10–4
Trimethylamine (CH3)3N 6.3×10–5
Triethylamine (C2H5)3N 5.6×10–4
Ethylamine CH3CH2NH2 6.3×10–4
Ethylenediamine (CH2NH2)2 8.3×10–5
Pyridine C5H5N 1.7×10–9
Hydroxylamine NH2OH 8.7×10–9
Aniline C6H5NH2 7.4×10–10
Hydrazine H2NNH2 1.3×10–6


Organic Compounds
Compound Formula Ka      Kb
Ammonia
NH3
 1×10–35 1.8×10–5
Methylamine CH3NH2   5.0×10–4
Dimethylamine (CH3)2NH   5.4×10–4
Trimethylamine (CH3)3N   6.3×10–5
Ethylamine CH3CH2NH2   6.3×10–4
Triethylamine (CH2H5)3N   5.6×10–4
Diethylamine (C2H5)2NH
6.9x10–4
Ethylenediamine (CH2NH2)2
8.3x10–5
Pyridine C5H5N   1.7×10–9
Hydroxylamine NH2OH  1.1×10–6 8.7×10–9
Aniline C6H5NH2  1×10–27 7.4×10–10
Methanol CH3OH   3×10–16 6.3×10–17
Ethanol CH3CH2OH 1.2×10–16 1×10–17
n-Propanol CH3CH2CH2OH  1×10–16  
2-Propanol CH3CH(OH)CH3  8×10–18  
Acetone CH3COCH3  5×10–20 1.0×10–21
Urea H2NCONH2
1.5×10–14
Water  H2O  1.82×10–16 1.82×10–16
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