Abstract
The solubility, solubility product and the thermodynamic functions for the CeF3−H2O system have been measured using the radiometric, conductometric and potentiometric techniques. The radiometric values for the solubility and solubility product, the lowest and more acceptable for reasons cited in previous papers, are 3.14·10−5 M and 2.17·10−17 respectively. The enthalpy change measured by the conductometric method is almost twice as that obtained by potentiometric method due to abnormal conductances registered at higher temperatures. The average values for ΔHo and ΔGo and ΔSo at 298 K are 53.0±17.4, 91.7±4.0 and −129.7±58.2 KJ·mol−1 respectively. The positive values for ΔHo and ΔGo and the negative value for ΔSo are indicative of the low solubility of this salt in water. The stability constants for the mono- and difluoride complexes of Ce(III) have been determined potentiometrically using unsaturated solution mixtures of Ce(III) and F−. These values for CeF+ and CeF +2 are 997±98 and (1.03±0.44)·105, respectively. Studies on pH dependence of the solubility shows that the solubility reaches a minimum value at a pH of about 3.2.
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Menon, M.P., James, J. & Jackson, J.D. Complexation, solubilities and thermodynamic functions for cerium(III) fluoride-water system. Journal of Radioanalytical and Nuclear Chemistry, Articles 102, 419–428 (1986). https://doi.org/10.1007/BF02047916
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DOI: https://doi.org/10.1007/BF02047916