Abstract
The stoichiometric pK *1 and pK *2 for the ionization of sulfurous acid has been determined from emf measurements in NaCl solutions with varying concentrations of added MgCl2 (m=0.1, 0.2 and 0.3) from I=0.5 to 6.0 molal at 25°C. These experimental results have been treated using both the ion pairing and Pitzer's specific ion-interaction models. The Pitzer parameters for the interaction of Mg2+ with SO2 and HSO −3 yielded λ=0.085±0.004, β(0) = 0.35±0.02, β(1) = 1.2±0.04, and Cφ = −0.072±0.007. The Pitzer parameters β(0) = −2.8±0.4, β(1) = 12.9±2.9 and β(2) = −2071±57 have been determined for the interactions of Mg2+ with SO 2−3 . The calculated values of pK *1 and pK *2 using Pitzer's equations reproduce the measured values to within ±0.04 pK units. The ion pairing model with log KMgSO3=2.36±0.02 and logγMgSO3 = 0.1021, reproduces the experimental values of pK *2 to ±0.01. These results demonstrate that treating the data by considering the formation of MgSO3 yields a better fit of the experimental measurements with fewer adjustable parameters. With these derived coefficients obtained from the Pitzer equations and the ion pairing model, it is possible to make reliable estimates of the activity coefficients of HSO −3 and SO 2−3 in seawater, brines and marine aerosols containing Mg2+ ions.
Similar content being viewed by others
References
D. Dyrssen and I. Hansson,Mar. Chem. 1, 137 (1973).
R. M. Pytkowicz and J. E. Hawley,Limnol. Oceanogr. 19, 223 (1974).
V. Thurmond and F. J. Millero,J. Solution Chem. 11, 447 (1982).
F. J. Millero and V. Thurmond,J. Solution Chem. 12, 401 (1983).
F. J. Millero and D. R. Schreiber,Am. J. Sci. 282, 1508 (1982).
F. J. Millero,Thalassia Jugoslavia 18, 253 (1982).
F. J. Millero,Geochim. Cosmochim. Acta 47, 2121 (1983).
F. J. Millero, J. P. Hershey, G. Johnson, and J. Z. Zhang,J. Atmosph. Chem. 8, 377 (1989).
K. S. Pitzer, inActivity Coefficients in Electrolyte Solutions, R. M. Pytkowicz, ed., Vol. 1, (CRC Press, 157, 1979).
G. Arena, E. Rizzarelli, S. Sammartano, and C. Rigano,Talanta 26, 1 (1979).
L. M. Connaughton, J. P. Hershey, and F. J. Millero,J. Solution Chem. 15, 989 (1986).
C. E. Harvie and J. H. Weare,Geochim. Cosmochim. Acta 44, 981 (1980).
K. S. Pitzer and G. Mayorga,J. Phys. Chem. 77, 2300 (1973).
T. H. Kim and J. W. Frederick, Jr.,J. Chem. Eng. Data 33, 177 (1988).
K. S. Pitzer and G. Mayorga,J. Solution Chem. 3, 539 (1974).
C. E. Harvie, N. Moller, and J. H. Weare,Geochim. Cosmochim. Acta 48, 723 (1984).
K. S. Pitzer and J. J. Kim,J. Am. Chem. Soc. 96, 5701 (1974).
R. N. Roy, J. J. Gibbons, D. P. Bliss, Jr., R. G. Casebolt, and B. K. Baker,J. Solution Chem. 9, 911 (1980).
R. N. Goldberg and V. B. Parker,J. Res. Natl. Bur. Std. 90, 341 (1985).
J. P. Hershey, M. Fernandez, P. J. Milne, and F. J. Millero,Geochim. Cosmochim. Acta 50, 143 (1986).
J. P. Hershey, T. Plese, and F. J. Millero,Geochim. Cosmochim. Acta 52, 2047 (1988).
C. P. Kerr, inThermodynamics of Aqueous Systems with Industrial Applications, S. A. Newman, ed., (ACS Symp. Series, Vol. 133, Ch. 5, 1980), p. 91.
K. S. Pitzer and G. Mayorga,J. Chem. Soc. Faraday Trans. II 68, 101 (1972).
Author information
Authors and Affiliations
Rights and permissions
About this article
Cite this article
Roy, R.N., Zhang, JZ. & Millero, F.J. The ionization of sulfurous acid in Na−Mg−Cl solutions at 25°C. J Solution Chem 20, 361–373 (1991). https://doi.org/10.1007/BF00650763
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF00650763