Locus of Binary and Ternary Azeotropes in Chloroform-Methanol-Acetone Mixture
Consider a ternary mixture of chloroform, acetone, and methanol at . The vapor-liquid equilibrium (VLE) behavior is described by a modified form of Raoult's law with activity coefficients predicted by the Wilson model .[more]
This mixture presents four azeotropes, whose compositions and boiling points are:
This Demonstration shows the density plot of the function . At azeotropes, and thus ; also for pure components (i.e., at the vertices of the triangle).
This mixture presents three binary azeotropes and a ternary azeotrope. Azeotropes and pure components can be readily identified by the orange-colored regions. You can drag the locator to display the corresponding value of the function . Locator coordinates (i.e., the mole fractions of chloroform and acetone in the liquid phase) are displayed in the upper-right corner. The last snapshot shows a situation where the value of is very small near the ternary azeotrope, .[less]
 G. M. Wilson, "Vapor-Liquid Equilibrium XI: A New Expression for the Excess Free Energy of Mixing," Journal of the American Chemical Society, 86(2), 1964 pp. 127–130.