Low-temperature heat capacity and standard molar enthalpy of formation of the complex Zn(Thr)SO4·H2O (s)

Low-temperature heat capacities of the complex Zn(Thr)SO4·H2O (s) have been precisely measured with a small sample adiabatic calorimeter over the temperature range from 78 to 373 K. The initial dehydration temperature of the complex (Td=325.50 K) has been obtained by analysis of the heat-capacity curve. The experimental values of molar heat capacities have been fitted to a polynomial equation by least square method. The standard molar enthalpy of formation of the complex has been determined from the enthalpies of dissolution (ΔdHmΘ) of [ZnSO4·7H2O (s) +Thr (s)] and Zn(Thr)SO4·H2O (s) in 100 ml of 2 mol dm−3 HCl solvent as: ΔfHm,Zn(Thr)SO4·H2OΘ=−2111.7±3.4 kJ mol−1. These experiments were made by using an isoperibol solution calorimeter at 298.15 K.