Iodide Catalyzed Decomposition of H2O21,2
Adapted from references 1 and 2 by J. M. McCormick
Last Update: November 3, 2013
The kinetics of the iodide catalyzed decomposition of H2O2 will be studied at different temperatures and concentrations to test the proposed mechanism. The reaction’s progress will be followed by monitoring the change in pressure as O2 is evolved. You are referred to the literature1 for further background on the reaction and methods to be used.
A literature procedure will be followed.1 IMPORTANT! This procedure uses the method of initial rates. Therefore, it is not necessary to follow the reaction to completion and it may not be necessary to partially evacuate the reaction vessel before adding the iodide (see reference 2). Although you may wish to evaluate this for yourself.
A Vernier pressure sensor interfaced to a computer through the LabPro interface and LoggerPro software. Click here to review the basic operating procedure for the Vernier pressure sensor and the LoggerPro software. Because we are not interested in the absolute value of the pressure, only the change in the pressure, you will only need to calibrate the sensor at a single point (ambient pressure). The reaction will be studied initially at 25 °C using a water bath.
Once you have determined the order with respect to each reactant. Study how the rate of reaction changes as a function of temperature, and from these data determine the activation energy.
Present a typical kinetics trace of pressure as a function of time as well as the graphs you used to determine the orders with respect to each reactant. The methods for doing this are outlined in reference 1 and in the on-line review of kinetics. Show your Arrhenius plot and give your value of the activation energy.
Discuss whether your results are consistent with the proposed mechanism and with previous results.
1. Hansen, J. C. J. Chem. Educ. 1996, 73, 728-732. Click here to download this file (Truman addresses and J. Chem. Educ. subscribers only).
2. Abramovitch, D. A.; Cunningham, L. K. and Litwer, M. R. J. Chem. Educ. 2003, 80, 790-792. Click here to download this file (Truman addresses and J. Chem. Educ. subscribers only).