Differential ebulliometric method

Vapour pressures can be measured directly using a differential ebulliometric method [81,82], or by static measurements with different kinds of manometers [83-85]. 

Although calorimetric methods are usually regarded as yielding the most accurate enthalpies of vaporization [39], the measurement of the saturation vapor pressures of a liquid as a function of temperature is also widely used for the same purpose and may afford good quality data. Among these so-called vapor pressure methods [35], differential ebulliometry is probably one of the most reliable. Briefly, the ebulliometric method consists in measuring the boiling temperatures of a liquid at different pressures. In the differential set-up, the pressure over the... 

This paper describes an ebulliometric system for routine and special determinations of molecular weights. The system uses a simple ebulliometer, an immersion heater, and a Cottrell-type pump. Temperature sensing is by differential thermopile. Precision varies from about 1 to 6%, and values compare well with those from other laboratories and those from other methods. Values as high as 170,000 have been successfully measured. Some problems encountered in using the ebulliometric method are selection and effect of reference temperature, limitations of the vapor lift pump and a possible substitute for it, measurement of equilibrium concentrations within the operating ebulliometer, and the experimentally determined ebulliometric constant and some factors which influence its value. 

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See also in sourсe #XX -- [ ]

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