Abstract
The stoichiometric pK *1 and pK *2 for the ionization of carbonic acid has been determined from emf measurements in NaCl soluions to 6.0m at 25°C. Our results at low concentrations are in good agreement with the results of Harned and Bonner, of Dyrssen and Hansson and of Roy et al. The calculated values of pK *1 using Pitzer's equations agree with the measured values to ±0.01 pK units provided higher order terms are used. It was necessary to use a triplet interaction parameter (ψ) and higher order electrostatic terms (Eθ) to calculate reliable values of pK *2 (±0.03 pK units) over the entire concentration range. These results demonstrate the reliability of the Pitzer equations to estimate activity coefficients in concentrated salt solutions.
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Thurmond, V., Millero, F.J. Ionization of carbonic acid in sodium chloride solutions at 25°C. J Solution Chem 11, 447–456 (1982). https://doi.org/10.1007/BF00647107
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DOI: https://doi.org/10.1007/BF00647107