The Vapor Pressures of Sulphur between 100° and 550° with related Thermal Data

Representation of the vapour pressures of sulfur

“…We concluded that the coefficients shown above are inconsistent with equation (1) and that this equation is not a suitable model to use to represent the vapour pressures of sulfur. In spite of the problems we experienced with equation (1), we used both the experimental data and the calculated values reported by these authors to evaluate the quality of the other vapour pressure equations.…”

“…(1) The mirror image representation by equation (10) serves to indicate that all the signs of the coefficients are incorrect. Therefore, the correct form of equation (10) should read:…”

“…West and Menzies (1) measured the vapour pressures of sulfur at temperatures ranging from 376.63 K to 816.23 K. These authors presented the following equation and coefficients for the representation of their experimental data:…”

“…These authors then applied thermodynamic principles to their vapour pressure results and obtained an estimated vapour pressure value of 18208 kPa (179.7 atm) for sulfur at T = 1313 K. The accepted values of the critical temperature and critical pressure for sulfur appear to be T c = 1313 K and p c = 18208 kPa, respectively; these values have been listed in some thermodynamic property data compilations. (3,6) Rau et al (2) used their own results with some of those reported by West and Menzies (1) to develop the following equation for representing the vapour pressures of sulfur over the temperature range of 590 K to 1313 K:…”

“…(1,2) Various kinds of equations for representing these data have been reported by several authors. (1)(2)(3)(4)(5)(6) However, as shown in the following, none of these equations can represent satisfactorily the vapour pressures of sulfur over a wide temperature range of (vapour + liquid) equilibrium. In addition to this problem, there are errors in some of the vapour pressure equations for sulfur that are not immediately obvious.…”