Density and compressibility of superheated carbon tetrachloride

The effect of both pressure and temperature on the specific volume of carbon tetrachloride was determined using a new experimental technique. An apparatus, called a capillary pycnometer, was constructed which enabled extension of existing data on liquid densities into the superheated region. In brief, the apparatus consisted of a spherical quartz bulb attached to a long uniform section of capillary tubing in such manner as to enable superheating of the liquid contained in the bulb. Specific volume data were obtained by noting changes in level of the liquid meniscus in the (vertical) capillary caused by changes in either pressure or temperature in the bulb. Data were taken along four isotherms (69.83°C, 76.53°C, 82.23°C, and 88.03°C) under conditions of increasing pressure (falling meniscus) as well as decreasing pressure (rising meniscus). No hysteresis in the results was obtained for pressures ranging from 418 mm Hg to 1104 mm Hg. The maximum superheat reported in this study is 13.1°C (obtained at 88.03°C and 718 mm Hg), although values as high as 42°C were obtained during normal operation of the apparatus. Since the pycnometer system devised yielded only relative density values, it was necessary to obtain one absolute value to convert the other changes observed into absolute values. The data of Gibson and Loeffler were used for this purpose; in particular, a value of 1.49558 grams per cubic centimeter at 69.83°C was chosen. Thus, the data reported here can be no more accurate, on an absolute basis, than that reported by Gibson and Loeffler; however, an error analysis reveals that the data obtained here, treated on a relative basis, is superior to any yet reported