Measurement of Heat Capacity by Adiabatic Calorimetry and Calculation of Thermodynamic Functions of Standard Substances: Copper, Benzoic Acid, and Heptane (For Calibration of an Adiabatic Calorimeter)

Measurements of the heat capacity of standard specimens of copper, benzoic acid, and heptane and their thermodynamic functions of molar heat capacity, change in entropy, and enthalpy have been carried out at a low-temperature thermal-physical installation in the temperature range (4.2 up to 320) K using the method of adiabatic calorimetry. The obtained data are in good agreement with the recommended values. The relative uncertainty limits of the calorimetric unit: ± 1.43 % at T = 5 K, ± 0.75 % at T = 10 K, ± 0.23 % at T = 40 K, and less than ± 0.11 % for the temperature range (90 up to 298.15) K have been determined according to the experimental data of measurements of the certified measure of oxygen-free electronic (OFE) grade copper heat capacity. According to the heptane heat capacity measurement, the values of its enthalpy and entropy of fusion at Tfus = 182.54 K, ΔHfus = (14047 ± 19.6) J·mol−1 and ΔSfus = (76.96 ± 0.11) J·mol−1·K−1, have been determined. These values are also in a satisfactory agreem...