Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

ABSTRACT

Dichloro bis(2-aminopyridine) zinc (II), ZnCl2(C5H6N2)2(s), was synthesized by the method of solvonthermal synthesis in which 2-aminopyridine and zinc chloride were chosen as the reactants. X-ray crystallography, chemical analysis, and elemental analysis were applied to characterize the structure and composition of the complex. Low-temperature heat capacities of the title compound were measured with a precise small-sample automated adiabatic calorimeter over the temperature range from 78 K to 398 K. A polynomial equation of the heat capacities as a function of temperature was fitted by a least-squares method. Smoothed heat capacities and thermodynamic functions of the compound relative to the standard reference temperature (298.15 K) were calculated and tabulated at intervals of 5 K based on the fitted polynomial.Areasonable thermochemical cyclewas designed, and the standardmolar enthalpies of dissolution for the reactants and products of the synthesis reaction in a selected solvent were measured by an isoperibol solution-reaction calorimeter. In addition, the enthalpy change of the reactionwas calculated from the data of the above standardmolar enthalpies of dissolution. Finally, the standardmolar enthalpy of formation of the complex ZnCl2(C5H6N2)2(s)was determined to be-(400.52+-1.66) kJ*mol-1 in accordance with Hess s law.