This Demonstration shows the residue curve of a non-ideal ternary mixture composed of chloroform, acetone, and methanol at a total pressure of 10 atm. Deviation from ideal gas phase behavior must be considered. Indeed, the vapor-phase fugacity coefficient is computed using the Soave–Redlich–Kwong equation of state. This mixture presents three binary azeotropes and a ternary azeotrope, marked in the ternary diagram by for . Azeotropes appear as extrema of the residue curves. You can drag the locator and the program will plot the residue curve passing through the locator position. The location of the ternary azeotrope has been determined separately since it is neither a stable nor an unstable node. Compositions of all binary azeotropes are obtained from the residue curve calculations, as follows: