A plot of (feed molar flow rate)/(rate of reaction) versus fractional conversion is used to demonstrate how to minimize total reactor volume for two isothermal reactors in series. Select the order of the plug flow reactor (PFR) and continuous stirred-tank reactor (CSTR) with buttons. Use buttons to select the reaction kinetics for ; the reaction can be first order, second order or a Langmuir–Hinshelwood mechanism . The colored areas are proportional to the reactor volumes. The PFR volume is proportional to the area under the curve (from inlet to outlet conversion), and the CSTR volume is the difference between inlet and outlet conversion multiplied by the axis ratio at the reactor outlet. Use sliders to select the fractional conversion exiting each reactor.