Thermochemical Study on Ternary Solid Complex of La(Gly)2 (Ala)3 Cl3 ·2H2O (s)

The complex of lanthanum chloride with Glycine and Alanine, La(Gly)2(Ala)3Cl3 · 2H2O, was synthesized and characterized by IR, elementary analysis, thermogravimetric analysis, and chemical analysis. The dissolution enthalpies of LaCl3 · 7H2O(s), 2Gly(s) + 3Ala(s) and La(Gly)2(Ala)3Cl3 · 2H2O(s) were determined in 2 mol · L−1 HCl by a solution-reaction isoperibol calorimeter. By designing a thermochemical cycle in terms of Hess' Law and through calculation, the reaction enthalpy of lanthanum chloride seven-hydrate with Glycine and Alanine was obtained: ΔrHθm(298.15 K) = (29.652 ± 0.504) kJ · mol−1, and the standard enthalpy of formation of La(Gly)2(Ala)3Cl3 · 2H2O(s) ΔfHθm[La(Gly)2 (Ala)3Cl3 · 2H2O, s, 298.15 K] = −4467.6 ± 8.3 kJ · mol−1.