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In the article “Don’t Be Tricked by Your Integrated Rate Plot” (1), Edward Urbansky describes the possible pitfalls of using integrated rate plots. I think the point the author raises is valid, and one should be careful to avoid pitfalls like this. However, as a practising kineticist, I find it most disturbing that the author attributes the error to using an integrated rate plot. In fact, it clearly arises from linearizing the integrated rate law. Urbansky claims that “treatment of reaction order necessarily requires presentation of the linear integrated rate plots”. However, the unfortunate statistical consequences of linearization are well known, and the preferable practice is to use the original (non-linear) integrated rate laws and a non-linear least squares fitting algorithm (2). Comparing measured and fitted curves and observing the residuals of the fit will always reveal deviations that could be hidden in linearization.
Most of these arguments are also clearly presented in various sections of Espenson’s textbook (2). Literature Cited- Urbansky, E. T. J. Chem. Educ. 2001, 78, 921.
- Espenson, J. H. Chemical Kinetics and Reaction Mechanisms, 2nd ed.; McGraw-Hill: New York, 1995.
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