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  Home > JCE Print > Journal of Chemical Education > Issues > 2001  > July  >
In the Classroom
Don't Be Tricked by Your Integrated Rate Plot!
Edward Todd Urbansky
National Risk Management Research Laboratory, Water Supply and Water Resources Division, U.S. Environmental Protection Agency, 26 West Martin Luther King Drive, Cincinnati, OH 45268-0001
Cover
July 2001
Vol. 78 No. 7
p. 921
Abstract
Reaction order can be determined from kinetic data in a variety of ways. Two common methods are comparison of initial rates (while varying reactant concentration) and plotting integrated rate expressions. Both of these are introduced in general and physical chemistry textbooks. However, the limitations of the integrated rate plot approach are generally not covered. For the integrated rate plot to be used to confirm first-order kinetics, at least 4-5 half-lives' worth of data are required. Deviations from linearity between first- and second-order analyses of first-order data are not observed until the third half-life. Moreover, such deviation may be masked by indeterminate error. These points are demonstrated using simulated first-order kinetic data when conditions are idealized and when a random error of up to ±10% is introduced into the concentration values.

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More Information
*  Citation
 Urbansky, Edward T. J. Chem. Educ. 2001 78 921.
*  Keywords
 Introductory / High School Chemistry; Kinetics; Mechanisms; Teaching / Learning Aids; Teaching/Learning Theory/Practice; Textbooks
*  History
 Created:
Last Updated:		 June 6, 2001
August 31, 2005
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