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)

Abstract

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 T fus = 182.54 K, ΔH fus = (14047 ± 19.6) J·mol−1 and ΔS fus = (76.96 ± 0.11) J·mol−1·K−1, have been determined. These values are also in a satisfactory agreement with the reference data.

Heat Capacities of Natural Antlerite and Brochantite at Low Temperature

“…Measurements of the antlerite heat capacity have been performed by the method of adiabatic calorimetry in a low-temperature thermophysical installation produced by CJSC “Termis” (Mendeleevo, Moscow region). The calorimeter uncertainty when measuring a standard sample of the heat capacity measure (copper of the grade OFC) does not exceed ± 0.0144 at 5 K, about ± 0.0023 at 40 K, and less than ± 0.0011 over the range of (80 to 300) K . The temperature is measured with an iron–rhodium resistance thermometer RIRT3 ( R 0 = 50 ohm) calibrated in the VNIIFTRI (National Research Institute for Physicotechnical and Radio Engineering Measurements) in accordance with ITS90.…”

Structural Characteristics and Thermodynamic Functions of Compounds Ba(La1–xPrx)2WO7 (x from 0.005 to 0.05)

“…Measurements of the heat capacity of the samples obtained were carried out from the temperature of liquid helium to 320 K by adiabatic calorimetry on a low-temperature thermophysical installation manufactured by Termax. 35 The samples weighed between 0.9 and 1.2 g; the measurement step was between 0.3 and 3 K depending on the temperature range, and the measurement range was from 4.25 to 320 K. In the temperature region of helium, the heat capacity was measured at least twice. In the temperature region of nitrogen, the number of runs was 5 and more times.…”

Crystal Structure and Thermodynamic Properties of Barium–Thulium Bismuthate with Perovskite Structure

“…The experimental study of the heat capacity by adiabatic calorimetry method has been carried out over the temperature range of 5–320 K in a low‐temperature thermophysical apparatus produced by “Termax” company (Moscow). The calorimeter accuracy in accordance with a standard reference of the heat capacity measure (annealed oxygen‐free copper) is ±1.43% at 5 K, ±0.75% at 10 K, ±0.23% at 40 K, and less than 0.11% for the temperature range 90–298.15 K. The weight of the perovskite sample in a titanium container of 1 cm 3 was 2.5755 g. The measurement pitch was 0.3 K at 4–6 K, 0.5 K at 6–10 K, 2 K at 20–70 K, and 3 K over 70 K. The time of heating and measurement of calorimeter drift was 600 s.…”