Consider an ideal ternary mixture subject to an equilibrium-limited chemical reaction . The relative volatilities are taken as and . Pure is fed to the still. The Demonstration plots the residue curve (red) for this ternary reactive mixture as well as the equilibrium curve (green). It is clear that as the value of the Damköhler number, , becomes large, the residue curve approaches the equilibrium curve more rapidly. After some time, both curves will overlap for high . Only component will be left in the still after a long enough time. You can vary the Damköhler number as well as the equilibrium constant.