Thermodynamics Research Center / ThermoML | Journal of Chemical and Engineering Data

ABSTRACT

The equilibrium solubility of the ternary system cadmium chloride + l-threonine + water was determined at 298.15 K, and the corresponding equilibrium diagram was constructed. The ternary system is complicated with four equilibrium solid phases, CdCl2*2.5H2O, CdCl2*H2O, Cd(C4H9NO3)Cl2*H2O, and C4H9NO3, of which a new compound of Cd(C4H9NO3)Cl2*H2O was found to be incongruently soluble in the system. The new compound obtained was identified and characterized by the methods of FT-IR, elementary analysis, powder X-ray diffraction, single X-ray diffraction, and thermogravimetric and differential thermal analysis. It belongs to the monoclinic system, space group P2(1)/, with a = 0.7672(4) nm, b = 0.9166(5) nm, c = 1.3787(7) nm, ss = 96.453(7)deg , V = 0.9634(8) nm3, Dc = 2.188 g*cm 3, and Z = 2. The dissolution enthalpies of CdCl2, C4H9NO3, and Cd(C4H9NO3)Cl2*H2O in 2 mol*dm 3 hydrochloric acid were measured by heat conduction microcalorimetry. By designing an appropriate thermochemical cycle according to Hess s law and through calculation, the reaction enthalpies of formation were found to be -(9.28 +- 0.30) kJ*mol 1 for l-threonine with cadmium chloride, and the standard molar enthalpies of formation were found to be -(1493.8 +- 0.4) kJ*mol 1 for Cd(C4H9NO3)Cl2*H2O.