Vapour pressures of n-pentane determined by comparative ebulliometry

The vapour pressures of n-pentane have been measured using comparative ebulliometry with water as the reference substance. The measurements cover the temperature and pressure ranges 309 K and 102 kPa to 456 K and 2728 kPa. When combined with selected literature results, the range was extended downwards to a temperature and pressure of 268.8 K and 19.9 kPa and the combined data sets were correlated by a Wagner-type equation with a standard deviation of 18 Pa in the vapour pressure. The critical pressure was treated as an adjustable parameter and the value pc = 3367.4 kPa was obtained using a selected critical temperature, Tc = 469.7 K. The calculated normal boiling temperature was Tb = 309.207 K and an extrapolation to the triple point temperature Ttp = 143.48 K predicted a pressure of ptp = 0.078 Pa.