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 pc was treated as an adjustable parameter and the value of pc = 3027 kPa was calculated from the smoothing equation using a selected critical temperature of Tc = 507.49 K. The calculated normal boiling temperature is Tb = 341.866 K and an extrapolation to the triple-point temperature Ttp = 177.87 K predicts a triple-point pressure of ptp = 1.23 Pa.