Thermodynamics Research Center / ThermoML | International Journal of Thermophysics

Low-Temperature Heat Capacities and Standard Molar Enthalpy of Formation of Dichloro Bis(2-aminopyridine) Zinc (II), ZnCl2(C5H6N2)2(s)

Dan, W.-Y.[Wen-Yan], Di, [You-Ying], Liu, Y.-J.[Yan-Juan], Kong, Y.-X.[Yu-Xia], Tan, Z.-C.[Zhi-Cheng]
Int. J. Thermophys. 2010, 31, 11-12, 2103-2118
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.
Compounds
# Formula Name
1 Zn zinc
2 Cl2 chlorine
3 H2 hydrogen
4 N2 nitrogen
5 C graphite
6 Cl2Zn zinc chloride
7 ClH hydrogen chloride
8 H2O water
9 C10H12Cl2N4Zn dichlorobis(2-aminopyridine)zinc
Datasets
The table above is generated from the ThermoML associated json file (link above). POMD and RXND refer to PureOrMixture and Reaction Datasets. The compound numbers are included in properties, variables, and phases, if specificied; the numbers refer to the table of compounds on the left.
Type Compound-# Property Variable Constraint Phase Method #Points
  • POMD
  • 9
  • Mass density, kg/m3 ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • X-ray analysis
  • 1
  • POMD
  • 9
  • Molar heat capacity at constant pressure, J/K/mol ; Crystal
  • Temperature, K; Crystal
  • Pressure, kPa; Crystal
  • Crystal
  • Vacuum adiabatic calorimetry
  • 126
  • POMD
  • 6
  • 7
  • 8
  • Molar enthalpy of solution, kJ/mol ; Liquid
  • Ratio of mass of solute to volume of solution, kg/m3 - 6; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Solvent: Amount concentration (molarity), mol/dm3 - 7; Liquid
  • Liquid
  • ISOPERIBOL
  • 1
  • POMD
  • 7
  • 8
  • 9
  • Molar enthalpy of solution, kJ/mol ; Liquid
  • Ratio of mass of solute to volume of solution, kg/m3 - 9; Liquid
  • Temperature, K; Liquid
  • Pressure, kPa; Liquid
  • Solvent: Amount concentration (molarity), mol/dm3 - 7; Liquid
  • Liquid
  • ISOPERIBOL
  • 1
  • RXND
  • 1
  • 2
  • 9
  • 3
  • 4
  • 5
  • Molar enthalpy of reaction, kJ/mol
  • Solution calorimetry
  • 1