Thermodynamic properties of fluorine compounds. Part 15.—Vapour pressures of the three tetrafluorobenzenes and 1,3,5-trichloro-2,4,6-trifluorobenzene
The vapour pressures were measured of 1,2,4,5-tetrafluorobenzene from 5 kPa to the critical pressure, of 1,2,3,5-tetrafluorobenzene from 5 kPa to 470 kPa, of 1,2,3,4-tetrafluorobenzene from 7 kPa to 202 kPa, and of 1,3,5-trichloro-2,4,6-trifluorobenzene from 3 kPa to 180 kPa. The results were fitted by Antoine equations (applicable at pressures up to 200 kPa) and by Chebyshev equations. For each compound one of the latter equations is applicable over the whole range up to the critical temperature, and it is shown that the variation with temperature of ΔH/ΔZ calculated from this equation is similar to that found for other compounds.