Abstract
The first and second acidity constants of phosphoric acid were determined in a 0.70 ionic strength solution of both a sodium and a potassium ion background salt at 25°C. These experimentally determined constants were compared to literature values as well as values calculated from a theoretical model. Assuming negligible ion pairing of the phosphate ligand with the potassium ions, the stability constants of the NaHPO -4 and NaH2PO 04 complexes were determined to be 1.3±0.3 and 0.49±0.07 (mol-L−1), respectively. These constants were used to model the speciation of orthophosphate in a background of a sodium salt from pH 3 to 10.
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References
E. Atlas, C. Culberson, and R. M. Pytokowicz,Marine Chem. 4, 243 (1976).
SAS User's Guide, SAS Institute, Inc., Box 8000, Cary, NC 27511 (1981).
D. R. Migneault and R. K. Forcé,J. of Automatic Chem. 9, 125 (1987).
R. K. Forcé, J. Boyd, and E. Harris,Interfaces in Computing 1, 59, (1982).
R. M. Smith and R. A. Aberty,J. Phys. Chem. 60, 180 (1956).
P. G. Daniele, C. Rigano, and S. Sammartano,Talanta 30, 81 (1983).
R. G. Bates,Determination of pH, Theory and Practice (Wiley, New York, 1973).
R. M. Smith and A. E. Martell,Critical Stability Constants, Volume 4: Inorganic Complexes (Plenum Press, New York, 1981).
D. P. Shoemaker and C. W. Garland,Experiments in Physical Chemistry (McGraw-Hill, New York, 1967).
W. Strumm and J. J. Morgan,Aquatic Chemistry (Wiley, New York, 1981).
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Migneault, D.R., Forcé, R.K. Dissociation constants of phosphoric acid at 25°C and the ion pairing of sodium with orthophosphate ligands at 25°C. J Solution Chem 17, 987–997 (1988). https://doi.org/10.1007/BF00649742
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DOI: https://doi.org/10.1007/BF00649742