Chemical Education Today edited by
Book & Media Reviews
Jeffrey Kovac University of Tennessee Knoxville, TN 37996-1600
An Introduction to Chemical Kinetics by Margaret Robson Wright John Wiley & Sons: West Sussex, England, 2004. 462 pp. ISBN 0470090596 (paperback). $39.95; ISBN 0470090588 (cloth) $110. reviewed by Matthew Elrod
If one were to poll students on the most difficult subjects presented in the typical undergraduate physical chemistry course, I suspect that thermodynamics and quantum chemistry would run neck-and-neck in the survey. Perhaps this is the reason that many good physical chemistry texts are available for these subjects, but decidedly fewer are available that provide a similarly comprehensive treatment of the third major subject area of physical chemistry, kinetics. Indeed, while I have adopted several textbooks that contain high quality thermodynamics and quantum chemistry treatments, I have always felt that I was just “limping by” with the kinetics treatments contained in these same texts. As an atmospheric chemist, I have always found this situation discouraging, as my field (among many other growing interdisciplinary areas) relies quite heavily on the tools and methods of kinetics. Margaret Robson Wright has taken aim at this deficiency by authoring this dedicated text on the subject. While An Introduction to Chemical Kinetics was inspired by Wright’s years as an instructor at the Universities of Dundee and St. Andrews, I believe that the subject coverage and level of treatment are quite appropriate for the U.S. physical chemistry undergraduate audience as well. The novel organization of the text reflects Wright’s intention to demonstrate the importance of the experiment-based phenomenological roots of kinetics as well as the leading theories of chemical reactions before proceeding to discuss the important chemical applications of kinetics. Following some brief introductory remarks on the history of kinetics and its wide application in chemistry, the second chapter focuses on the leading experimental methods in kinetics. I particularly appreciate Wright’s explicit separation of the kinetics experiments into the somewhat separable issues of species detection and rate measurement. To the best of my knowledge, no other undergraduate kinetics treatment provides such a comprehensive development of the various experimental approaches. The third chapter contains most of the phenomenological framework of kinetics usually found in undergraduate treatments: rates, rate laws, determination of rate laws, integrated rate laws, pseudo first-order approach, steady state approximation, reversible reactions, and the Arrhenius expression. However, Wright takes an unusually painstaking approach to the subject of rate laws. For example, concentration vs. time graphs are explicitly deconstructed to reveal the concentration dependence of rates and the concept of the half-life before these quantities are derived from the integrated rate laws. My initial reaction to this approach was that it was not appropriate 40
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for physical chemistry students who have been previously exposed to such concepts in an introductory chemistry course. However, one of my frustrations in teaching kinetics in the physical chemistry course is that while most students become comfortable with the process of deriving and using integrated rate laws, many don’t seem to have an intuitive grasp of the utility of the rate laws. Perhaps Wright’s approach is appropriate, as it attempts to build the intuitive connections (how the various kinetics parameters affect concentration vs. time data) before moving on the actual machinery used by kineticists (integrated rate laws). The fourth chapter delves into theories of chemical reactions, starting with simple collision theory, and proceeding to both the statistical and thermodynamic formulations of transition state theory. Wright then uses this theoretical background to address the historically interesting development of unimolecular dissociation theory. The fifth chapter deals with the direct use of potential energy surfaces to understand the true multidimensional dynamical character of chemical reactions. The sixth chapter describes gas phase applications of the concepts laid out in the preceding chapters. Unfortunately, this chapter focuses on the mechanisms of the usual suspects in physical chemistry texts—chain reactions, H2 + Br2, the Rice-Herzfeld mechanism, the kinetics of explosions—and does not provide any examples from atmospheric chemistry, which is arguably the most active area of gas phase kinetics at present. The seventh chapter focuses on reactions in solution, with an extensive treatment of transition state theory for non-ideal solutions. The eighth and final chapter provides examples of applications in solution phase kinetics, with an appropriate emphasis on enzyme kinetics. The pedagogical organization of the chapters reflects Wright’s philosophical approach to the subject. In particular, there are many “nuts and bolts” descriptions of how to perform specific kinetics skills. For example, in my lectures I always present a checklist method for applying the steady state approximation. Wright actually provides such a checklist in her text! Through the use of at least ten “Worked Problems” in each chapter, it is clear that Wright intends that students solve problems as they read through the text. Although I affirm the point that such problems must be worked to really understand the kinetics concepts, I find such extensive use of these problems to be distracting, as one often has to turn several pages to resume the narrative. As a side note, the narrative itself could have benefited from a more concise writing style; more than once, I had to reread lengthy sentences in order to grasp the points being made. Finally, each chapter concludes with several more “Further Problems,” which could conceivably form the basis for class assignments, although the full solutions to all problems are included in the back of the text. In general, the textbook succeeds in its intended purpose. Because of its singular focus and extended length, it provides a much more detailed treatment of kinetics than is available in most comprehensive physical chemistry texts. The material is presented in a relatively modular fashion, so that in-
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structors can easily pick and choose the topics appropriate for their course (an important aspect, since it is unlikely that the whole text could be covered in the time usually allotted to kinetics in a standard physical chemistry sequence). Steinfeld, Francisco, and Hase’s Chemical Kinetics and Dynamics (1) would have to be considered one of the few quality alternatives to Wright’s text. However, I think the much more expensive Steinfeld et al. text is more appropriate for an advanced undergraduate or graduate course in kinetics. Nonetheless, since the Wright text would be have to be considered “supplementary” for use in physical chemistry courses (obviously, another text would be needed for the thermodynamics and quantum chemistry subjects), instructors would have to weigh
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whether the additional cost of the text is worth the improved treatment of kinetics. For instructors who have struggled to provide a stimulating and complete treatment of kinetics for their students, the answer may well be “yes”. Literature Cited 1. Steinfeld, J. I.: Francisco, J. S.; Hase, W. L. Chemical Kinetics and Dynamics, 2nd ed.; Pearson Education: New York, 1998.
Matthew Elrod is in the Department of Chemistry, Oberlin College, 119 Woodland Street, Oberlin, OH 44074;
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