Periodic Table of Elements
Constants and Variables
Vapor Pressure of Water
Ionization Energies, Electron Affinities, and Electronegativities
Ionization Constants for Weak Acids at 25º C
Ionization Constants for Weak Bases at 25º C
Standard Reduction Potentials
Thermodynamic Values (A-C)
Thermodynamic Values (F-O)
Thermodynamic Values (P-Z) Bibliography
Ionization Constants for Weak Acids at 25º C Acid Acetic Formula and Ionization Equation CH3CO2H H+ + CH3CO2- Ka 1.8 x 10-5 Arsenic H3AsO4 H+ + H2AsO4- H2AsO4- H+ + HAsO42- HAsO42- H+ + AsO43- K1 = 2.5 x 10-4 K2 = 5.6 x 10-8 K3 = 3.0 x 10-13 Arsenous H3AsO3 H+ + H2AsO3- H2AsO3- H+ + HAsO32- K1 = 6.0 x 10-10 K2 = 3.0 x 10-14 Benzoic C6H5CO2H H+ + C6H5CO2- 6.3 x 10-5 Butanoic HC4H7O2 H+ + C4H7O2- 1.52 x 10-5 Boric H3BO3 H+ + H2BO3- H2BO3 H+ + HBO32- HBO32- H+ + BO33- K1 = 7.3 x 10-10 K2 = 1.8 x 10-13 K3 = 1.6 x 10-14 Carbonic H2CO3 H+ + HCO3- HCO3- H+ + CO32- K1 = 4.2 x 10-7 K2 = 4.8 x 10-11 Chromic H2CrO4 H+ + HCrO4- HCrO4- H+ + CrO42- 5.0 1.5 x 10-6 Citric H3C6H5O7 H+ + H2C6H5O7- H2C6H5O7- H+ + HC6H5O72- HC6H5O72- H+ + C6H5O73- K1 = 7.4 x 10-3 K2 = 1.7 x 10-5 K3 = 4.0 x 10-7 Cyanic HOCN H+ + OCN- 3.5 x 10-4 Formic HCO2H H+ + HCO2- 1.8 x 10-4 Hydrazoic HN3 H+ + N3- 1.9 x 10-5 Hydrocyanic HCN H+ + CN- 4.0 x 10-10 Hydrofluoric HF H+ + F- 7.2 x 10-4 Hydrogen Peroxide H2O2 H+ + HO2- 2.4 x 10-12 Hydrosulfuric H2S H+ + HS- HS- H+ + S2- K1 = 1 x 10-7 K2 = 1 x 10-19 Hypobromous HOBr H+ + OBr- 2.5 x 10-9 Hypochlorous HOCl H+ + OCl- 3.5 x 10-8 Hypoiodus HOI H+ + OI- 2.3 x 10-11 Iodic HIO3 H+ + IO3- 1.69 x 10-1 Lactic HC3H5O3 H+ + C3H5O3- 1.38 x 10-4 Malonic H2C3H2O4 H+ + HC3H2O4- HC3H2O4- H+ + C3H2O42- 1.4 x 10-3 2.0 x 10-6 Nitrous HNO2 H+ + NO2- 4.5 x 10-4 Oxalic H2C2O4 H+ + HC2O4- HC2O4- H+ + C2O42- K1 = 5.9 x 10-2 K2 = 6.4 x 10-5 Phenol C6H5OH H+ + C6H5O- 1.3 x 10-10 Phosphoric H3PO4 H+ + H2PO4- H2PO4- H+ + HPO42- HPO42- H+ + PO43- K1 = 7.5 x 10-3 K2 = 6.2 x 10-8 K3 = 3.6 x 10-13 Phosphorous H3PO3 H+ + H2PO3- H2PO3- H+ + HPO32- K1 = 1.6 x 10-2 K2 = 7.0 x 10-7 Phthalic H2C8H4O4 H+ + HC8H4O4- HC8H4O4- H+ + C8H4O42- 1.1 x 10-3 3.9 x 10-6 Propanoic HC3H5O2 H+ + C3H5O2- 1.34 x 10-5 Selenic H2SeO4 H+ + HSeO4- HSeO4- H+ + SeO42- K1 = very large K2 = 1.2 x 10-2 Selenous H2SeO3 H+ + HSeO3- HSeO3- H+ + SeO32- K1 = 2.7 x 10-3 K2 = 2.5 x 10-7 Sulfuric H2SO4 H+ + HSO4- HSO4- H+ + SO42- K1 = very large K2 = 1.2 x 10-2 Sulfurous H2SO3 H+ + HSO3- HSO3- H+ + SO32- K1 = 1.7 x 10-2 K2 = 6.4 x 10-8 Tartaric H2C4H4O6 H+ + HC4H4O6- HC4H4O6- H+ + C4H4O62- 9.2 x 10-4 4.3 x 10-5 Tellurous H2TeO3 H+ + HTeO3- HTeO3- H+ + TeO32- K1 = 2 x 10-3 K2 = 1 x 10-8 home site map/index background information chemical reactions states of matter acid/base reactions thermodynamics redox reactions atoms and molecules organic chemistry nuclear chemistry help features reference thinkquest