Equilibrium Constants For Acids and Bases in Aqueous Solution                         Return
Ka Ionization (or dissociation constant for an acid A (charged or otherwise) = equilibrium constant [H+][B-]/[A] for A <===> H+1 + B-1.    Likewise,Kb, the ionization constant (or dissociation constant of a base B = equilibrium constant [A+][OH-]/[B] for B<===> A+1 + OH-1
Acid or Ion Equilibrium (all in aqueous solution) K    pK   pK   K
Perchloric HClO4  <=====>  H+1 + ClO4-1 very large ------- ------- -------
Hydroiodic HI  <=====>   H+1 + I-1 very large ------- ------- -------
Hydrobromic HBr  <=====>  H+1 + Br-1 very large ------- ------- -------
Hydrochloric HCl  <=====>   H+1 + Cl-1  very large ------- ------- -------
Sulphuric H2SO4  <=====>  H+1 + HSO4-1  very large ------- ------- -------
Nitric HNO3  <=====>  H+1 + NO3-1  40 1.6 ------- -------
Chromic(VI) H2CrO4  <===>  H+1 + HCrO4-1 10  1.00 14.00 1.0 x 10-14
Trichloroethane CCl3CO2H  <=>  H+1 + CCl3CO2-1  2.3 x 10-1 0.64 13.36 4.37 x 10-14
Iodic(V) HIO3  <=====>  H+1 + IO3-1  1.7 x 10-2 0.78 13.22 6.03 x 10-14
Oxalic HO2CCO2H  <==>  H+1 + HOOCCOO-1 5.4 x 10-2 1.27 12.73 1.86 x 10-13
Dichloroethanoic CHCl2COOH  <==>  H+1 + CHCl2COO-1 5.0 x 10-2 1.30 12.70 2.00 x 10-13
Sulphurous H2SO3  <=====>  H+1 + HSO3-1  1.5 x 10-2 1.82 12.18 6.61 x 10-13
Phosphoric H3PO4  <=====>  H+1 + H2PO4-1  1.6 x 10-2  1.80  12.20 6.31 x 10-13
Chloric(III) HClO2  <=====>  H+1 + ClO2-1 1.0 x 10-2 2.00 12.00 1.00 x 10-12
Hydrogen sulphate HSO4-1  <=====>  H+1 + SO42- 1.0 x 10-2  2.00 12.00 1.00 x 10-12
Phosphoric(V) H3PO4  <=====>  H+1 + H2PO4-1  7.9 x 10-2 2.10 11.90 1.26 x 10-12
Iron(III) ion Fe(H2O)63+  <==>  H+1 + Fe(H2O)5(OH)2+ 6.0 x 10-3  2.22 11.78 1.66 x 10-12
Hydrogen telluride H2Te  <=====>  H+1 + HTe-1 2.3 x 10-3 2.64 11.36 4.37 x 10-12
Chloroethanoic CH2ClCOOH <==>  H+1 + CH2ClCOO-1  1.3 x 10-3 2.89 11.11 7.76 x 10-12
Citric H3C6H5O7  <=====>  H+1 + H2C6H5O7+1 7.1 x 10-4  3.15 10.85 1.41 x 10-11
Nitrous HNO2  <=====>  H+1 + NO2-1 7.1 x 10-4 3.15 10.85 1.41 x 10-11
Hydrofluoric HF  <=====>  H+1 + F-1 5.6 x 10-4  3.25 10.75 1.78 x 10-11
Hydrogen selenide H2Se  <=====>  H+1 + HSe-1 1.7 x 10-4 3.77 10.23 5.89 x 10-11
Methanoic (Formic) HCOOH  <====>  H+1 + HCOO-1 1.6 x 10-4  3.80 10.20 6.31 x 10-11
Chromic ion Cr(H2O)63+  <=>  H+1 + Cr(H2O)5(OH)2+ 1.5 x 10-4 3.82 10.18 6.61 x 10-11
Lactic  C3H6O3  <=>   H+1 + C3H5O3-1 1.2 x 10-4 3.92 10.08 8.32 x 10-11
Barbituric HC4H3N2O3 <===>  H+1 + C4H3N2O3-1  9.8 x 10-5 4.01 9.99 1.02 x 10-10
Ascorbic C6H8O6  <=====>  H+1 + C6H7O6-1  7.9 x 10-5 4.10 9.90 1.26 x 10-10
Benzoic C6H5COOH  <==>   H+1 + C6H5COO-1 6.3 x 10-5 4.20 9.80 1.59 x 10-10
Hydrogen oxalate HOOCCOO-1  <=>  H+1 + 1-OOCCOO-1  5.4 x 10-5 4.27 9.73 1.86 x 10-10
Phenylammonium ion C6H5NH3+1  <=====>  H+1 + C6H5NH2 2.0 x 10-5 4.70 9.30 5.01 x 10-10
Ethanoic CH3COOH  <==>  H+1 + CH3COO-1 1.7 x 10-5 4.77 9.23 5.89 x 10-10
n-Butanoic C3H4COOH  <===> H+1 +C3H4COO-1 1.5 x 10-5 4.82 9.18 6.61 x 10-10
Propanoic C4H5COOH   <==>   H+1 + C4H5COO-1  1.3 x 10-5 4.89 9.11 7.76 x 10-10
Aluminum ion Al(H2O)63+ <==>   H+1 + Al(H2O)5(OH)2+  1.0 x 10-5 5.00 9.00 1.0 x 10-9
Dihydrogen phosphite H2PO3-1  <===>   H+1 + HPO32-  6.3 x 10-7 6.21 7.79 1.62 x 10-8
Carbonic H2O + CO2  <=====>  H+1 + HCO3-1   4.5 x 10-7 6.35  7.65 2.24 x 10-8
Hydrogen chromate HCrO4-1  <==>  H+1 + CrO42- 3.2 x 10-7 6.50 7.50  3.16 x 10-8
Hydrogen sulphide H2S  <=====>  H+1 + HS-1  8.9 x 10-8  7.05 6.95 1.12 x 10-7
Hydrogen sulphite HSO3-1  <==>  H+1 + SO32- 6.2 x 10-8 7.21 6.79 2.0 x 10-7
Dihydrogen phosphate H2PO4-1 <===>  H+1 + HPO42- 6.2 x 10-8 7.21 6.79 2.0 x 10-7
Hypochlorous HClO  <=====>  H+1 + ClO-1  3.7 x 10-8 7.43 6.57 3.0 x 10-7
Telluric H5TeO6  <=====>  H+1 + H4TeO6-1 2.0 x 10-8 7.70 6.30 5.02 x 10-7
Hypobromous HBrO  <=====>  H+1 + BrO-1  2.1 x 10-9 8.68 5.32 4.8 x 10-6
Boric H3BO3  <=====>  H+1 + H2BO3-1  5.8 x 10-10 9.24 4.76 1.74 x 10-5
Ammonium ion NH4+1  <=====>  H+1 + NH 5.6 x 10-10 9.25 4.75 1.78 x 10-5
Hydrocyanic HCN  <=====>  H+1 + CN-1 4.9 x 10-10 9.31 4.69  2.04 x 10-5
Silicic H2SiO3  <=====>  H+1 + HSiO3-1 1.3 x 10-10 9.89 4.11  7.69 x 10-5
Ethane-1,2-diammonium C2H9N2+1 <===> H+1 + CH3NHCH2NH2 1.3 x 10-10 9.89  4.11 7.69 x 10-5
Phenol C6H5OH  <=====>  H+1 + C6H5O-1 1.28 x 10-10 9.88 4.12 7.81 x 10-5
Butylammonium  C4H9NH3+1 <===>   H+1 + C4H9NH 5.0 x 10-11 10.30 3.70  1.0 x 10-4
Hydrogen carbonate HCO3-1  <==>  H+1 + CO32-  4.8 x 10-11 10.32 3.68  2.10 x 10-4
Hydrogen telluride H4TeO6-1 <==> H+1 +  H3TeO62-  1.0 x 10-11 11.00 3.00 1.0 x 10-3
Hydrogen peroxide H2O2  <===>  H+1 + HO2-1  2.4 x 10-12 11.62 2.38 4.17 x 10-3
Hydrogen silicate HSiO3-1  <==>  H+1 + SiO32- 1.3 x 10-12 11.89 2.11  7.76 x 10-3
Hydrogen phosphate HPO4-2  <==>  H+1 + PO43-  4.4 x 10-13 12.36 1.64 2.29 x 10-2
Hydrogen sulphide HS-1  <=====>  H+1 + S2-  1.2 x 10-13 12.92 1.08 8.3 x 10-2
Water H2O  <=====>  H+1 + OH-1  1.0 x 10-14 14.00 0.00 1.0