IUPAC-NIST Solubility Data Series. 92. Metal Carbonates. Part 1. Solubility and related thermodynamic quantities of cadmium(II) carbonate in aqueous systems

摘要

This paper, devoted to cadmium(II) carbonate, is the first in a series dedicated to the solubility of compounds relevant to mobility of metals in the environment. Here, we present compilations and critical evaluation of the experimental solubility data for cadmium(II) carbonate, otavite, in aqueous ternary and higher-order systems. The solubility of cadmium(II) carbonate depends on temperature, carbon dioxide partial pressure, pH, the presence of complexing ions, and ionic strength of the solution. Papers referring to solubility of cadmium(II) carbonate have been published since 1901; the thorough search of the literature in this field covered the period from 1901 through 2009. The compilation of the available experimental data is introduced with a critical evaluation. The evaluation of the experimental data considers the possible correlation between the data obtained under similar experimental conditions of temperature, carbon dioxide partial pressure, electrolyte, and ionic strength. Those experiments where the solid phase was well identified and the interactions between the electrolyte and the dissolved cadmium(II) ion were considered practically negligible were used to determine the thermodynamic properties of the solid cadmium(II) carbonate. Recommended values for the thermodynamic quantities are lg*K(ps0)(degrees) = 6.11 +/- 0.10, Delta(f)G degrees(CdCO(3), cr, 298.15 K) = -(674.3 +/- 0.6) kJ mol(-1), Delta(f)H degrees(CdCO(3), cr, 298.15 K) = -(752.2 +/- 0.8) kJ mol(-1), S degrees(CdCO(3), cr, 298.15 K) = (103.9 +/- 0.2) J K(-1) mol(-1).