Effect of impurities upon pure component thermophysical properties Academic Article uri icon


  • This article first derives thermodynamic relations between the dew-point/bubble-point gap, the infinite dilution activity coefficient (γ2∞), and Henry′s constant (H21) for binary mixtures where the first component is the pure (solvent) component and the second component is the impurity (solute). Equations for prediction of these quantities from a one-fluid van der Waals (VdW-1) model give poor results. Both relative volatility and chemical nature of the two species are shown to affect significantly the dew-/bubble-point gap. We recommend the UNIFAC method for prediction of infinite dilution activity coefficients. A priori prediction of the dew-/ bubble-point gap with impurity level follows, allowing the experimentalist to confirm his measurements when (1) the impurities are known by prior analysis or (2) the impurities have been formed by decomposition of the pure component. Five example cases are presented, including the effect of decomposition on the vapor pressure curve of “pure” hydrogen sulfide. © 1987, American Chemical Society. All rights reserved.

author list (cited authors)

  • Eubank, P. T., Kim, E. S., Holste, J. C., & Hall, K. R.

citation count

  • 5

publication date

  • October 1987