Estimation of the Solubility Constant of Calcite, Aragonite, and Vaterite at 25°C Based on Primary Data Using the Pitzer Ion Interaction Approach

Summary.

 Experimentally determined values of the solubility constant of anhydrous calcium carbonate species were compiled from primary literature. The data were processed using a least-squares technique and the activity coefficients were calculated using the Pitzer ion interaction model. It was shown that the literature data considered can be divided into two data sets which are internally consistent, but mutually inconsistent. The first data set was consistent with the existence of the CaHCO₃ ⁺ ion pair, while the second data set was not. It was assumed that the difference between the two data sets might be due to surface charge effects.