High temperature saturated vapour pressure of sulphur and the estimation of its critical quantities

Vapour pressure measurements on sulphur were performed up to a temperature of 1273 K (144.5 atm) with the aid of a special all-silica Bourdon gauge. Densities of the coexisting vapour and liquid were measured to 1273 K (vapour) and 1193 K (liquid). From the results the critical quantities of S were estimated to be: critical temperature, To = 1313 K; critical pressure, pc = 179.7 atm; critical volume, Vc = 158 cm3 mol−1; critical density, pc = 0.563 g cm−3; mean number of atoms per molecule at the critical point, vo = 2.78. The vapour pressure of sulphur between 590 K and the critical point is given by the formula:log⁡10(psat/atm)=60.9106-24971(K/T)+1.0817×107(K/T)2−2.2060×109(K/T)3−14.4102log⁡10(T/K).