AN ADIABATIC SOLUTION CALORIMETER USED FOR MEASURING THE MOLAR EXCESS ENTHALPY OF THE SYSTEM CARBON TETRACHLORIDE – BENZENE AT 25 °C

Abstract

A new adiabatic calorimeter for measuring heats of mixing is described. The design of the mixing cell avoids the presence of a vapor space, and accommodates changes in volume by means of a flexible diaphragm. The apparatus is equipped with automatic adiabatic control and produces a continuous record of the temperature of the mixing cell. An extensive series of measurements was carried out for the system carbon tetrachloride – benzene at 25 °C. The maximum value of the molar excess enthalpy, 113.4 ± 0.5 J mole⁻¹, occurred at a mole fraction of carbon tetrachloride equal to 0.4907. For most of the concentration range, the results are from 1 to 2 J mole⁻¹ lower than data reported recently by other investigators.