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

Abstract

The equilibrium solubility of the quaternary system LuCl 3 -CdCl 2 -HCl-H 2 O 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, CdCl 2 • H 2 O, Cd 3 LuCl 9 • 14H 2 O (3:1 type), CdLuCl 5 • 9H 2 O (1:1 type), and LuCl 3 • 6H 2 O, of which the new compounds Cd 3 LuCl 9 • 14H 2 O and CdLuCl 5 • 9H 2 O 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 Cd 3 LuCl 9 • 14H 2 O and CdLuCl 5 • 9H 2 O 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.

Phase Equilibrium System of HoCl3−CdCl2−HCl(7.52 %)−H2O at 298.15 K and Standard Molar Enthalpy of Formation of Cd4HoCl11·14H2O

“…But for the quaternary systems TbCl 3 −CdCl 2 −HCl−H 2 O and DyCl 3 −CdCl 2 −HCl−H 2 O, there are only three equilibrium solid phases (CdCl 2 ·H 2 O, Cd 4 TbCl 11 ·14H 2 O, and TbCl 3 ·6H 2 O) and (CdCl 2 ·H 2 O, Cd 9 Dy 2 Cl 24 ·29H 2 O, and DyCl 3 ·6H 2 O). We re-examined the YCl 3 −CdCl 2 −HCl−H 2 O, ErCl 3 −CdCl 2 −HCl−H 2 O, and LuCl 3 −CdCl 2 −HCl−H 2 O systems and confirmed that the YCl 3 −CdCl 2 −HCl−H 2 O system is composed of four equilibrium solid phases: CdCl 2 ·H 2 O, Cd 4 YCl 11 ·13H 2 O, Cd 5 Y 2 Cl 16 ·26H 2 O, and YCl 3 ·6H 2 O, respectively. For the ErCl 3 −CdCl 2 −HCl−H 2 O system, four equilibrium solid phases (CdCl 2 ·H 2 O, Cd 9 Er 2 Cl 24 ·29H 2 O, CdEr 7 Cl 23 ·42H 2 O, and ErCl 3 ·6H 2 O) were observed.…”

“…Phase equilibria of quaternary systems of RECl 3 −CdCl 2 −HCl(∼8 %)−H 2 O (RE = La, Ce, Pr, Nd, Eu, Tb, Dy, Y, Er, Lu) at 298.15 K have been previously reported. − It is highly valuable and important for us to understand the phase relations and interactions of RECl 3 and CdCl 2 in aqueous media. Li et al and Wang et al , reported the presence of four equilibrium solid−phase regions (CdCl 2 ·H 2 O, Cd 8 RECl 19 · n H 2 O, Cd 4 RECl 11 ·12H 2 O, and RECl 3 ·7H 2 O) (RE = La, Pr, n = 16, 20) in the LaCl 3 −CdCl 2 −HCl−H 2 O and CdCl 2 −PrCl 3 −HCl−H 2 O quaternary systems.…”

“…Phase equilibria of quaternary systems of RECl 3 -CdCl 2 -HCl(∼8 %)-H 2 O (RE ) La, Ce, Pr, Nd, Eu, Tb, Dy, Y, Er, Lu) at 298.15 K have been previously reported. [1][2][3][4][5][6][7][8][9][10] It is highly valuable and important for us to understand the phase relations and interactions of RECl 3 and CdCl 2 in aqueous media. Li et al and Wang et al 1,3 reported the presence of four equilibrium solid-phase regions (CdCl The purity reached in this way was found to be 99.9 mass %.…”