Applicability of Raoult's law in nonideal mixed solvents


In general, the vapor-pressure change due to the addition of a solute to a solvent mixture does not follow Raoult's law. We have demonstrated thermodynamically that if one adds to a binary solvent mixture solute and solvents in such a way that the vapor-phase composition remains constant, then the decrease of total pressure follows Raoult's law; a supplementary term which vanishes for very dilute solute concentration is introduced as a consequence of the nonideality of the ternary solution. Precise vapor-pressure measurements of dilute solutions of electrolytes and nonelectrolytes in a 40.000 wt. % water-tetrahydrofuran mixture are used in order to illustrate the applicability of Raoult's law under the above conditions. These may be regarded as a particular case of what has been called endostatic conditions, i.e., addition of a solute under constant solvent activity ratio.

This is a preview of subscription content, access via your institution.


  1. 1.

    W. L. Miller,J. Phys. Chem. 1, 633 (1897); A. I. Johnson and W. F. Furter,Can. J. Chem. Eng., 78 (1960).

    Google Scholar 

  2. 2.

    R. Wright,J. Chem. Soc., 124, 2068 (1924).

    Google Scholar 

  3. 3.

    E. Grünwald and A. L. Barcarella,J. Am. Chem. Soc. 80, 3840 (1958); E. Grünwald, G. Baugham, and G. Kohnstam,J. Am. Chem. Soc. 82, 5801 (1960).

    Google Scholar 

  4. 4.

    E. Grünwald and A. Effio,J. Am. Chem. Soc. 96, 423 (1974).

    Google Scholar 

  5. 5.

    C. Treiner and P. Finas,J. Chim. Phys. 71, 76 (1974).

    Google Scholar 

  6. 6.

    C. Treiner,J. Chim. Phys. 70, 1183 (1973).

    Google Scholar 

  7. 7.

    C. Treiner and P. Tzias,J. Solution Chem. 4, 471 (1975).

    Google Scholar 

  8. 8.

    J. L. Hawes and R. L. Kay,J. Phys. Chem. 69, 2420 (1965).

    Google Scholar 

  9. 9.

    C. Treiner, J. F. Bocquet, and M. Chemla,J. Chim. Phys. 70, 68 (1973).

    Google Scholar 

Download references

Author information



Rights and permissions

Reprints and Permissions

About this article

Cite this article

Tzias, P., Treiner, C. & Chemla, M. Applicability of Raoult's law in nonideal mixed solvents. J Solution Chem 6, 393–402 (1977).

Download citation

Key Words

  • Raoult's law
  • endostatic conditions
  • ternary mixtures
  • vapor pressure
  • water-tetrahydrofuran
  • solute-solvent interactions