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An isoperibol solution-reaction calorimeter suitable for measuring molar enthalpies of solid-liquid and liquid-liquid interactions was constructed. The volume of calorimetric vessel made by transparent hard glass is about 100 cm 3 . Its energy equivalent is 0.48 kJ‚K -1 when containing 100 cm 3 of double distilled water. The thermal leakage modulus is 2.7 × 10 -4 s -1 . The time constant of the calorimeter is about 2.9 s. The precision of controlling and measuring the temperature is within (0.001 K and (0.0001 K, respectively. The performance of the calorimeter was tested by measuring the enthalpy of dissolution of KCl in double distilled water, ∆ s H m,KCl 0 ) (17 547 ( 13 J‚mol -1 ) at T ) (298.15 ( 0.001) K, and the measuring uncertainty was estimated to be within (0.30% by comparing our measured value with the reference. Molar enthalpies of dissolution of the {ZnCl 2 (s) + L-His(s)} mixture and the complex Zn(His)-Cl 2 ‚ 1 / 2 H 2 O(s) in 100 cm 3 of 2 mol‚L -1 HCl at T ) (298.15 ( 0.001) K have been measured to be ∆ d H m,1 0 ) (26.419 ( 0.019) kJ‚mol -1 and ∆ d H m,2 0 ) (11.862 ( 0.009) kJ‚mol -1 , respectively, by means of the isoperibol solution-reaction calorimeter. The standard molar enthalpy of formation of the complex Zn-(His)Cl 2 ‚ 1 / 2 H 2 O(s) has been derived to be3) kJ‚mol -1 by the combination of the experimental values of enthalpies of dissolution with some auxiliary thermodynamic data through a designed Hess thermochemical cycle on the basis of a supposed chemical reaction.

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4-Dimethylaminopyridine (DMAP) is an important catalyst. The thermodynamic properties of DMAP were investigated through differential scanning calorimetry, thermogravimetric analysis, adiabatic calorimetry, and combustion calorimetry. The low-temperature heat capacity (C p ,m) was measured in the temperature range from (80 to 402) K with a high-precision automated adiabatic calorimeter. The melting temperature (T m), the molar enthalpy (Δfus H m), and the entropy (Δfus S m) of fusion were determined to be (387.094 ± 0.002) K, (21.628 ± 0.144) kJ·mol-1, and (55.873 ± 0.372) J·K-1·mol-1, respectively. The mole fraction purity of the sample used in the adiabatic calorimetric study was determined to be 0.99964 according to the Van't Hoff equation. The thermodynamic functions [H T − H 298.15] and [S T − S 298.15] were derived in the range from (80 to 400) K with temperature interval of 5 K based on the heat capacity measurements. The constant-volume energy and standard molar enthalpy of combustion have been determined, Δc U (C7H10N2, cr) = −(4232.20 ± 0.60) kJ·mol-1 and Δc (C7H10N2, cr) = −(4235.92 ± 0.60) kJ·mol-1, by means of a precision oxygen-bomb combustion calorimeter at T = (298.15 ± 0.001) K. The standard molar enthalpy of formation has been derived, Δf (C7H10N2, cr) = (52.20 ± 1.71) kJ·mol-1, from the standard molar enthalpy of combustion in combination with other auxiliary thermodynamic quantities through a Hess thermochemical cycle.