Consider an ideal quaternary mixture subject to an equilibrium-limited chemical reaction . The relative volatilities are taken as , , , and . The products and appear as the highest and lowest boiling point components of this quaternary mixture. An equimolar mixture of and is initially fed to a reactive rectifier. For simplicity, assume that the reaction takes place only in the still. This Demonstration plots the distillate and still compositions versus time for user-set values of the Damköhler number (see parameter , which varies between 0 and 1, the reflux ratio , the equilibrium constant (used in the rate expression as follows: ), and the number of nonreactive stages in the rectifier . Compositions of components , , , and are plotted in red, blue, green, and magenta, respectively.