The equations of Pitzer have been used to calculate the stoichiometric ionization constants, pK*HA, for acids in NaCl media at 25°C. The calculated results for the ionization of HAc, H2O, B(OH)3, H2CO-3, H3PO4, H2PO-4, HPO2-4, H3AsO4, H2AsO-4 and HAsO2-4 are in good agreement with the measured values, providing higher order interaction terms (θ and ψ) are used. The pK*HA measurements of these acids in NaCl media containing Mg2+ and Ca2+ were used to determine Pitzer specific interaction parameters at I = 0.7. With these Pitzer coefficients, it was possible to make reliable estimates for the activity coefficients of anions in seawater (S = 35) that form strong interactions with Mg2+ and Ca2+. The calculated activity coefficients yield reliable estimates for the pK*HA of acids in seawater.
ASJC Scopus subject areas
- Geochemistry and Petrology