Micro conduction calorimeters to measure enthalpies of vaporization

Details of the construction of micro-conduction calorimeters for measuring enthalpies of vaporization (or sublimation) are described. Accuracy and precision of the calorimeters were tested by the use of a few standard reference compounds. Experimental results showed that the enthalpies of vaporization could be measured for compounds of vapor pressures of 10 Pa to 10 kPa at 298 K with uncertainty less than 0.2 per cent. Results of enthalpy of vaporization measurements for some compounds are also given. Since calorimetric cells of these calorimeters were composed of glass and PTFE, the calorimeters made it possible to measure the enthalpies of vaporization for metal corrosive compounds.