BOOK AND MEDIA REVIEW pubs.acs.org/jchemeduc
Review of Selected Problems in Physical Chemistry: Strategies and Interpretations Hal H. Harris* Department of Chemistry and Biochemistry, University of Missouri—St. Louis, St. Louis, Missouri 63121, United States can be paraphrased, “What amount of 238Pu would be required in order to power an implanted pacemaker with at least 100 μW of energy for 25 years?” The solution provided (and carefully explained) seemed to give an unrealistically small result (2.3 10 7 g), and so I checked the calculation and found that the answer should have been 1000 times larger, 2.3 10 7 kg. While this is still an extremely small mass, the Ilich result was beyond credibility. In this case, the error is not difficult to find because the logic and the computation are presented step-by-step. I would suggest that an additional step should be added to the author’s problem-solving strategy: make a final check that your answer is reasonable. By the way, nuclear-powered pacemakers were used on about 150 patients in the 1970s. The heat produced by a tiny sample of plutonium oxide was converted to an electrical current by a thermopile. This technology has since been replaced, largely by long-life lithium cells.1 The “reasonableness” of the result can also lead you astray, as it does with Ilich’s explanation of the low coefficient of friction under an ice skate as being a consequence of a pressure-induced phase transition. Unfortunately, this seductive hypothesis (which is still often found in textbooks) is an inadequate explanation of why ice is slippery. If a phase transition under the skate is necessary for low friction, then skating would be possible only at temperatures within a few degrees of the melting point, children would not be able to skate, and skiing would not be possible. A very good discussion of ice friction can be found in a recent Physics Today article2 and it is also addressed in several articles in this Journal3 5 and on Kevin Lehmann’s “Bad Chemistry” Web site.6 Ilich can take solace in the fact that he is not the only one to have gotten it wrong.7 Both the problems and their resolutions are often witty. For example, there is the illness of a citizen by the name of J. W. Gibbs, who has been brought to the hospital with a high fever. Instead of the normal 36.6 °C, Professor Gibbs’ temperature has risen to 41.2 °C. Treating the patient as 75 kg of pure water, the reader is asked to determine how much additional metabolic energy must have been generated to increase the temperature by that much. After the correct solution (1.35 MJ) is worked out, Ilich claims that this is equivalent to what would be expended by Professor Gibbs if he ran day and night for six days! The author speculates that this may be one of the reasons why a fever drains our energy. While there may be some truth to the hypothesis that fevers may increase fatigue by consuming extra energy, the assertion about how far that energy could take a runner is unwarranted; 1.35 MJ (322 kcal) would power his jogging for less than an hour.
Selected Problems in Physical Chemistry: Strategies and Interpretations by Predrag-Peter Ilich . Springer: Heidelberg, Dordrecht, London, New York, 2010. 210 pp. ISBN 978-3642043260 (paper). $39.95.
I have occasionally run across students who are less than enthusiastic about physical chemistry problems, and so I am always looking for interesting, context-rich settings for them. That is why I bought a copy of Selected Problems in Physical Chemistry, and I was not disappointed. For my students, this is a potentially very valuable guide; for me, it is a quite nice collection of 50 problems of easy-to-medium difficulty that could be used in most physical chemistry courses. The topics include mechanics, basic and chemical thermodynamics, electrochemistry, kinetics, and spectroscopy. The exercises are related to real-world situations or to phenomena most often treated in other branches of the chemistry curriculum. Detailed solutions are provided for each problem in an avuncular, conversational style. Beyond “how to solve this particular problem”, the student is given valuable advice and encouragement in a few pages for each of them (the 50 problems are discussed in just over 200 pages). A typical solution includes the development of a strategy that includes identification of the applicable principles, useful assumptions and approximations that one can use, and finally, the calculation part of the problem (which is what many students try to start with). Ilich also describes five “little big tricks”, that are mathematical techniques applicable to several different kinds of problems.
Cover image provided by Springer Verlag and reproduced with permission.
I must mention reservations I have with three of the problem solutions or explanations, however. The very first problem I read Copyright r 2011 American Chemical Society and Division of Chemical Education, Inc.
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dx.doi.org/10.1021/ed2004406 | J. Chem. Educ. 2011, 88, 1457–1458
Journal of Chemical Education
BOOK AND MEDIA REVIEW
Despite these few quibbles, I find much to like in this book. Given the cost of textbooks these days, it is not easy to suggest that students spend an additional $40.00 for a supplement, but this is one that would make most students better.
’ AUTHOR INFORMATION Corresponding Author
*E-mail:
[email protected].
’ REFERENCES (1) Alais, M.; Berger, R.; Boucher, R.; Gasper, K. A.; Laurens, P. Nucl. Technol. 1975, 26, 307–319. (2) Rosenberg, R. Phys. Today 2005, 58, 50–55. (3) Loucks, L. F. J. Chem. Educ. 1986, 63, 115–116. (4) Silberman, R. J. Chem. Educ. 1988, 65, 186. (5) Chang, R.; Skinner, J. F. J. Chem. Educ. 1990, 67, 789–790. (6) Bad Chemistry Home Page. http://www.faculty.virginia.edu/ lehmannlab/badchemistry.html (accessed Jul 2011). (7) Gramsch, S. A. J. Chem. Educ. 2000, 77, 718–724.
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dx.doi.org/10.1021/ed2004406 |J. Chem. Educ. 2011, 88, 1457–1458
