High temperature vapor pressure and the critical point of potassium

Abstract

The vapor pressure of potassium was experimentally determined from 2100 deg F up to-its critical temperature. An empirical equation of the form ln P = A + B/T + C ln T + DT/sup 1.5/ was found to best fit the data. A critical pressure of 2378.2 plus or minus 4.0 psia (161.79 plus or minus 0.27 ata) was measured. The corresponding critical temperature, extrapolated from the pressure-- temperature curve, is 4105.4 plus or minus 5 deg R (2280.8 plus or minus 3 deg K). The technique employed was tae pressure tube method developed earlier in this laboratory and used for determining the vapor pressure of rubidium and cesium. This method measures tae critical pressure directly, as well as the vapor pressure st lower temperatures. (4 tables, 6 figures, 26 references) (auth