Vapour pressures of n-hexane determined by comparative ebulliometry

The vapour pressures of n-hexane have been measured using comparative ebulliometry with water as the reference fluid. The measurements cover the temperature and pressure range (315.7 K 41.1 kPa) to (504.0 K, 2876.8 kPa) and join smoothly with results selected from the literature to provide consistent results down to (289.7 K, 13.8 kPa). The combined data set have been described by a Wagner style equation with a fractional standard deviation of 4.2 . 10(-5) in the vapour pressure. The critical pressure p(c) was treated as an adjustable parameter and the value of p(c) = 3027 kPa was calculated from the smoothing equation using a selected critical temperature of T-c = 507.49 K. The calculated normal boiling temperature is T-b = 341.866 K and an extrapolation to the triple-point temperature T-tp = 177.87 K predicts a triple-point pressure of p(tp) = 1.23 Pa. (C) 2005 Published by Elsevier Ltd.