Thermodynamic Investigation of Phase Equilibria in Metal Carbonate-Water-Carbon Dioxide Systems

摘要: Solubility measurements as a function of temperature have been shown to be powerful tool for the determination thermodynamic properties sparingly-soluble transition metal carbonates. In contrast calorimetric methods, such solution calorimetry or drop calorimetry, evaluation solubility data avoids many systematic errors, yielding enthalpy at 298.15 K with an estimated uncertainty ±3kJ·mol -1. A comprehensive set otavite (CdCO3), smithsonite (ZnCO3), hydrozincite (Zn5(OH)6(CO3)2), malachite (Cu2(OH)2CO3), azurite (Cu3(OH)2(CO3)2), and siderite (FeCO3) was derived. Literature values standard formation were disproved by these experiments, revised are recommended. case siderite, given various bases deviate from each other more than 10 kJ • mor1 which can attributed discrepancy in auxiliary Fee+ ion, critical literature sources results optimized value siderite. The Davies approximation, specific ion-interaction theory, Pitzer concept used extrapolation constants zero ionic strength order obtain valid infinite dilution, T = K, p =105 Pa. application electrolyte models both homogeneous heterogeneous (solid-solute) equilibria aqueous is reviewed. (Cu2(OH)2(CO3) (Cu3(OH)2(CO3)2) reviced 10kJ · mol-1 Fe2+ ion. enthalphy 298.15K, 105 (solid-solute)equilibria