SECTION 16: IONIZATION CONSTANTS IN AQUEOUS SOLUTIONS
A large body of information exists on the ionization of electrolytes in water at ambient temperatures. As early as the turn of the century, experiments were devised to obtain ionization constants for weak electrolytes in solutions in equilibrium with vapor at temperatures to 300° C, but only in the last decade have methods been developed for the determination of ionization constants in supercritical aqueous solutions. (The usefulness of these constants as a means of understanding hydrothermal, ionic equilibria has been apparent for some time from successful applications at lower temperatures.) In this relatively new field, there are sufficiently few data to make it possible for this compilation to be, hopefully, complete through 1963 in coverage of constants for water above 0° C and for inorganic compounds in aqueous solutions above the critical point of the solvent. In the subcritical region, constants are given where available for all compounds for which there are supercritical data, as well as for several inorganic acids and bases likely to be of common geologic interest. For ionization constants of other compounds (and commonly only near room temperature), the reader is referred to the exhaustive, but uncritical, compilation of stability constants by Sillén and Martell  covering the literature through 1960. Other less complete tabulations of ionization constants of inorganic aqueous species near 25° C include those by Parsons  and Yatsimirskiǐ and Vasil'ev .
All ionization constants given in the following tables are reported as the logarithms of thermodynamic constants, without dimensions, but are numerically