A new set of acidity constants for carbonic acid and boric acid in sea water

The dissociation constants of carbonic acid, the acidity constant of boric acid, and the ionic product of water have been determined by potentiometric titrations in synthetic sea water. The interpolated values for the salinity range of 20–40% and the temperature range of 5–30°C are given for carbonic acid in Table 5, for boric acid in Table 6, and for pKw in Table 4. The activity scale is chosen so that the activity coefficient approaches unity when the concentrations of H+, OH−, H2CO3+CO2, HCO3−, CO32−, B(OH)3 and B(OH)4− approach zero in synthetic sea water of a certain salinity. The concentration unit is Mw, moles per kg solution. Experimental methods and activity scales used by Buch, Harvey, Wattenberg and Gripenberg (1932), Buch (1938) and Lyman (1957) are reviewed. Comparisons of the concentrations of the carbonate species in a sample, obtained by use of tables given by Buch, Lyman and this work, are listed in Table 9.