Lattice potential energy and thermochemical properties of ethylenediamine dihydrochloride (C2H10N2Cl2)

Ethylenediamine dihydrochloride (C2H10N2Cl2)(s) was synthesized. The crystal structure of the compound has been determined by X-ray crystallography. The lattice potential energy and ionic radius of the cation of the compound were obtained from the crystallographic data. Molar enthalpies of dissolution of the compound in double-distilled water under various values of molality were determined at T = 298.15 K by an isoperibol solution-reaction calorimeter. Following to Pitzer’s theory, the molar enthalpy of dissolution of the compound at infinite dilution (ΔsolHm∞) and the Pitzer parameters (βMX(0)L and βMX(1)L) were obtained. The values of relative apparent molar enthalpies (ΦL  ), relative partial molar enthalpies (L¯2) of the compound and relative partial molar enthalpies (L¯1) of the solvent at different concentrations m/(mol · kg−1) were derived from the experimental values of the enthalpies of dissolution of the compound. Finally, the hydration enthalpy of the cation of the substance was calculated by designing a thermochemical cycle.