Phase Equilibrium System of LuCl3−CdCl2−HCl(7.47 %)−H2O at 298.15 K and Standard Molar Enthalpies of Formation of New Solid-Phase Compounds

• Published in: Journal of chemical and engineering data 2008-02, Vol.53 (2), p.471-474
• Main Authors: Qiao, Zhan-Ping, Zhuo, Li-Hong, Guo, Ying-Chen, Zhang, Shu-Shen
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Phase equilibria
• ISSN: 0021-9568; 1520-5134
• DOI: 10.1021/je700556p

The equilibrium solubility of the quaternary system LuCl3−CdCl2−HCl−H2O was determined at 298.15 K, and the corresponding equilibrium diagram was constructed in this paper. The quaternary system is complicated with four equilibrium solid phases, CdCl2·H2O, Cd3LuCl9·14H2O (3:1 type), CdLuCl5·9H2O (1:1 type), and LuCl3·6H2O, of which the new compounds Cd3LuCl9·14H2O and CdLuCl5·9H2O were found to be congruently soluble in the system. The two new compounds obtained were identified and characterized by the methods of X-ray diffraction, thermogravimetry, and differential thermogravimetry. The standard molar enthalpies of solution of Cd3LuCl9·14H2O and CdLuCl5·9H2O in deionized water were measured to be 28.79 ± 0.22 kJ·mol−1 and −15.48 ± 0.30 kJ·mol−1, respectively, by heat conduction microcalorimetry. Their standard molar enthalpies of formation were calculated to be −6427.5 ± 1.3 kJ·mol−1 and −4133.7 ± 0.7 kJ·mol−1, respectively.