The irreversible reaction A → B takes place in an isothermal plug-flow reactor (PFR). The rate of reaction and the fractional conversion are plotted versus space velocity (entering volumetric flow rate/reactor volume). As space velocity increases, the time available for reaction decreases. Use sliders to vary the dimensionless rate constant and dimensionless feed concentration. Select the reaction order with buttons. Conversion is high for smaller space velocities, regardless of the order of reaction, and for a first-order reaction, conversion is independent of feed concentration.

For all reactions the instantaneous rate is , where is the change in the moles of A with time, is the kinetic constant, is the concentration of A, and is the order of the reaction.

The conversion is calculated from

where is the space velocity, is the conversion of A, and is the conversion of A at the exit.

The conversion has an upper limit of 1, so that if at a given space velocity, then conversion is 1 at lower space velocities.

The overall rate is

where rate is the total number of moles reacting with time in the reactor, and is the feed concentration of A.

Negative first-order reaction:

instantaneous rate: 

conversion: 

Negative half-order reaction:

instantaneous rate: 

conversion: 

Zero-order reaction:

instantaneous rate: 

conversion: 

Half-order reaction:

instantaneous rate: 

conversion: 

First-order reaction:

instantaneous rate: 

conversion: 

Second-order reaction:

instantaneous rate: 

conversion: 

This simulation was created in the Department of Chemical and Biological Engineering at University of Colorado Boulder for LearnChemE.com by John L. Falconer using Claude AI. It is a JavaScript/HTML5 implementation of a Mathematica simulation by Derek M. Machalek. It was prepared with financial support from the National Science Foundation (DUE 2336987 and 2336988) in collaboration with Washington State University. Address any questions or comments to LearnChemE@gmail.com.