Low-temperature heat capacities and standard molar enthalpy of formation of complex Zn(Met)SO4•H2O(s)

Low-temperature heat capacities of complex Zn(Met)SO4 center dot H2O(s) have been precisely measured with a small sample precision automated adiabatic calorimeter over the temperature range from 78 to 370 K. The initial dehydration temperature of the complex (T-0=329.50 K) has been obtained by means of the analysis of a heat capacity curve. The experimental values of molar heat capacities have been fitted to a polynomial equation of heat capacities (Cp,m)vs. the temperature (7) with the least square method. The smoothed heat capacities and the thermodynamic functions of the complex have been calculated on the basis of the equation. In accordance with Hess law, the standard molar enthalpy of formation for the complex was detertnined as triangle(f) H-m(circle minus)= -(2069.30 +/- 0.74) kJ center dot mol(-1), by using an isoperibol solution-reaction calorimeter, M designing a thermochemical cycle and choosing 100 mL of 2 mol center dot dm(-3) HCl as calorimetric solvent.