New Kinetics Experiment for Undergraduate Chemical Engineering Laboratory

Dr. David Griffin, Dr. Bill Gilbert and Prof. Mark B. Shiflett

A new kinetics experiment shown in Figure 1 was completed and added to the undergraduate chemical engineering teaching laboratory for the Chemical Engineering Laboratory I, C&PE 616.  Students can measure the kinetic orders and activation energy for the iodination of acetone reaction (CH3COCH3  + I2 → CH3COCH2I +  HI) using HCl as a catalyst.

The reaction is a color change reaction so it starts as a colored solution when iodine is added (I2 is red/brown in color) and goes clear as the product iodoacetone is formed (iodoacetone is clear). The experimental setup consists of a 1 liter stirred tank reactor with a cooling/heating jacket controlled with a Peltier temperature bath.  A pump circulates a sample of the reactor fluid through a flow cell in a spectrometer for instantaneous analysis of the iodine concentration as a function of time.  The temperature and absorbance are recorded using a LabView® data acquisition program on a laptop computer.  The waste can be drained to waste containers beneath the reactor and the system is mounted on a moveable rack which allows the experiment to be portable.  The setup is identical on both sides of the rack so that students can work in groups of two to run both reactors simultaneously.  The spectrometer measures the absorbance of iodine at a wavelength of 510 nm.  Students use both a linear regression (Initial Rates Method) and a non-linear regression to analyze the kinetics data to determine the orders of reaction and the activation energy.  In addition to the experiments, students model the reaction using Aspen Plus using both batch (RBATCH) and continuous (RCSTR) reactor models. The fact that the experiment is portable allows the equipment to be wheeled into the classroom for demonstration during lectures.  Students taking Chemical Kinetics C&PE 524 will learn how the experiment works, the methods for data analysis and be assigned a homework set based on actually experimental data being measured by the Senior class.  This will connect the lab course with the kinetics course and familiarize the Juniors in C&PE 524 with the kinetics experiment they will do the following semester in the undergraduate laboratory course C&PE 616.  In addition, future experiments can be conducted with other reactants such as bromine and the effect of different catalysts can be studied.

A new thermodynamics experiment is planned for construction during the summer of 2017 and ready for use in C&PE 616 by the Fall semester.  The intent is by the Fall of 2018, that three new experiments focused on kinetics (complete), thermodynamics and fluid mechanics will be ready which connect the theory taught in the core courses with the laboratory course.  The experiments will be portable and allow instructors to describe the experiments in the classroom and build homework sets based on data measured by students to familiarize Juniors with the Senior laboratory equipment and analysis methods.