How Chemical Reactions Occur: An Introduction to Chemical Kinetics and Reaction Mechanisms
BOOK
Edward L. King, Univemity of Colorado, Boulder. W. A. Benjamin, Inc., New York, 1963. xi 148 pp. Figs. and tables. 14 X 21 cm. Paperbound. $1.95.
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REVIEWS
Four Poperbacks for General_Chemistry
Learning to learn without a. teacher is a skill thst is generally acquired through trial and error, often through reading first one book and then another, and then perhaps still another. For it is usually impossible for s, single book to supply consistently the right facts s t the right time to every reader. The reader intent upon learning without a teacher generally needs to examine many books. That most young students of science do not do this, thst they are, in fact, notoriously illiterate, reflects, in part, the Parkinsonian fact that formal curricula tend to expand to fill the available time and, further, the fact that until recently there existed few suitable books in science a t the beginning level. The young student desirous of learning more about chemical kinetics, for example, or thermodynamics, or spectroscopy, had little of real substance to turn to beyond the traditional textbooks in these fields, which, unfortunately for him, were generally developed in an unfamiliar mathematical language. The recent emergence a t the beginning level of intellectual, scientific paperbacks as supplements to, or substitutes for, traditional clothbound texts, and as material for enriching the educational fare of students, especially gifted and highly motivat,ed students, is therefore an event of considerable interest. Use of these paperbacks in a. general chemistry course naturally invites the question, "What is left out?" The answer often given is, "Descriptive Chemistry." If hy descriptive chemistry one means "Common chemistry that is not well-understood," thia choice can be easily appreciated. For some teachers all of the time and probably all teachers some of the time enjoy discussing phenomena that can he easily "explained!' And as often happens the common phenomena. that are easiest to observe in the laboratory are the most difficultto explain in lecture. Conversely, phenomena easy to explain in lecture mav often he difficultto observe in the laboratorv. This tends to lead to the development of l a w leet,urea and ex~ensivelaboratories. wiich msv be oedaeo&calls desirable but independently of each other. Another danger of emphssieing in the classroom those aspects of science that most easily can be explained is the dan~e-er that the subject may lose contact with its most characteristic feature, growth. Intr~duetorycourses, especially, have an important responsibility to convey to the student the knowledge that there do exist and perhaps always will exist within the domain of science common and imoortant facts that are not well-understood. In several of the books reviewed here there'is a tendency toward authoritarianism, although all of them carefully make the point that chemistry is still an experimentd science. In none of them, however, is there my discussion of the personalities of science and the evolution of scientific thought. Is thia because scientists of the present generation reared in the backwash of the early successes of quantum mechanics really do believe, as many then did, that all of chemistry is contained in the wave equation and that consequently the manner in which scientific concepts once developed is not important to the younger generation? Publication of these paperbacks raises, thus, some interesting questions and presents some new opportunities. Their use implies a topical approach to the subject which should encourage department-wide participation in general chemistry programs and, through this, effective use in subsequent courses of the students' early exposure to the major theories of modern chemistry. HENRYA. BENT Univwsity gf Minnesota MinneapolG
v v i e w e d in this Issue
Through s skillful blend of fact and theory and an adroit use of examples this excellently written book achieves in brief compass a remarkably complete, welldocumented, well-illustrated, and up-todate treatment of the important experimental and theoretical aspects of chemical kinetics. I t can be warmly recommended to d l students and teaohers of general chemistry, and to "those rtt more advanced levels in related fields," as an "introduction, or reintroduction, to the subject." For beginning students the book should form an instructive bridge between, on the one hand, chemical formulas and balanced equations and, on the other, later studies of molecular structure and chemial equilibrium. The book addresses itself to four questions: How rapidly do- reaction occur? How is reaction velocity influenced by changes in concentration? How is reaction velocity influenced by changes in temperature? Does reaction occur in one step or in a sequence of steps? After a brief introduction, the concepts of reaction mechanism (Chap. 2) and 16 action rate (Chap. 3) are carefully introduced and illustrated, the former by three reactions (the oueatep HZ 1% reaction, the multi-step oxidation of Fe(I1) by Cr(VI), m d the H,+Br, chain reaction), the latter by three different experimental measurements (the oxygen evolved in the decomposition of NIOain CCL, the change in electrical conductivity in the hydrolysis of an alkyl halide, and the change in light absorption in the oxidationof I - b y C10-). Well-conceived. well-drawn. and carefullv captioned illustrations help to make clear the experimental significance of these examples. Next (Chap. 4), experimentd rate laws for several of the reactions previously mentioned are described in full detail; in words, algebraically, in tabular form, and graphically. Included are first- and second-order rate laws, a rate law involving a catalyst, and a two-term rate law. Mechanisms for some of these rate laws are described later in Chapter 6. Also included is a timely digression on radioactive decay and an elegant suggestion on how to obtain experimentally, in lecture or in the leboratory, rate data far the reaction Hz02 312Hf = la- + 2Hs0. Suggestions such as this are only too rarely found in textbooks and are much to be prized. Theories of reaction kinetics are discussed next (Chap. 5). Bimolecular collision frequency is introduced in an interesting and relaxed manner in eight pages. The discussion uses to advantage several of the well-known results of kinetic moleculsrtheory. Elsewhere in thebook use is made of the gas laws, oxidation potentials, Le Chstelier's principle, and equilibrium constants. Reaction mechenisms are discussed in
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Edvard L. King, How Chemical Reactions Occur Bmce H. Mahan, Elementary Chemical Thermodynamics Gordon M. B a r n , The Structure of Molecules Werner Hem, The Shape of Carbon Compounds Siegfried Nussabaum, Organic Chemistry Ead R. Parker, Materials for Missiles and Spacecraft Robert F. Gould, editor, Saline Water Conversion-11
Volume 41, Number 7, January 1964
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Chapter 6. This discussion, together with those that precede it, should thoroughly prepare the student for the treatment of reversible reactions and chemical equC librium that follows in Chapter 7. Important points about chemical equilibrium are established with the aid of two wellchosen examples, one simple, the decomposition of hydrogen iodide, and one more eomolex. the deeamoosition of nitraua ' acid: The hook closes with brief, but readable chapters on catalysis, very fast reactions, and the use of isotopes. Also included is an Appendix on the meaning of the signs, =, -, 8 ,e;n useful Glossary; and a nice list of 34 articles on kinetics culled from Chemical Reviews, Quarterly Reviews, ~ n l JOURNAL, s and Seientifrc American. It should be noted, finally, that often much can be inferred about the effortand imagination that has gone into a.book from its problem. King's problems are "first rate." They make an excellent contribution to a fine volume that should find wide use among students of chemistry.
HENRYA. BENT University of Minnesota Minneapolis Elementary Chemical Thermodynamics
Bruce H. Mahan, University of California, Berkeley. W. A. Benjamin, Inc., 155 pp. Figs. New York, 1963. x and tables. 14 X 21 em. Pe+peperhound. $1.95. The conventional general chemistry course contains much concealed thermodynamics. Included, for exemple, are solubility products, ionization constants, and other constants of chemical equilihrium; oxidation-reduction potentials and electrochemistry; vapor pressure; freezing point lowering and boiling point rise effects; osmotic pressure; and Le Chatelier's principle. These applications of thermodynamics are capably described from s. (primarily) clc~ssicalpoint of view in this volume, which, although it introduces no major new physical and pedagogical insights, does contain a number of nice touches. Taken together the latter add up in the reviewer's opinion to a successful trettment of chemical thermodynamics for beginning students who have had, or are currently enrolled in, n beginning calculus course. (Mshan's book is the only one of the four reviewed that presumes a knowledge of calculus.) The book is divided into four chapters: an Introduction, the First Law, the Second Law, and Applications. The Introduction is s. business-like, and happily brief, discussion of several of classical thermodynamic's characteristic concepts (macroscopic properties, systems, states and state functions, equilibrium states, and temperature scales). In the second chapter, the First Law is introduced-with the aid of Newton's law and several integrations of "mathemrttically defined" work-in the familiar form AE = q - w and illustrated by readable discussions of thermochemistry, enthalpies of formation. bond energies, heat capacity, temperature dependence of AH, explosions and flames, and P - V cdlculstions on ideal gases. The last topic, though
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Journol of Chemiml Education
particularly well-worked out, prabably will not greatly fire the imagination of beginning students-a statement more about beginning students, perhaps, than about thermodynamics. In the third chapter, after discussing the need for another law with three examples (the free expansion of a gas, heat flowiromhot to cold, and theirreversible reaction of hydrogen and oxygen), the Second Law is introduced, rather abrupbly. in the form
chemistry who have enjoyed within recent years a conventional course in physical chemistry will probably wish to examine this book. The publisher is to be congratulated uoon the rare meed with which this book was put into print.
HENRYA. BENT University of Minnesota Minneapolis The Structure of Molecules: An Introduction to Molecular Spectroscopy
This is followed by several illustrative examples (reversible isothermal expansion of an ideal gas, free expansion of an ideal gas, and heat flow), a molecular interpretntion of entropy (S = RIN In R), and the deck-of-cards analogy ("The fundamental reason why the shuffled &ate is found after mixing tbe cards is that there are many microscopic states that are consistent with the shuffled condition and only one that is consistent with the ordered state.") In this way the author sidesteps what often becomes for the beginning student a. traumatic experience with Carnot's cycle and integrating factors. Completing the chapter are conventional, well-written discussions on the Gibbs free energy, eauilibrium constsnts. electrochemied e&, and the temperature dependence of equilibria. In the last chapter (Applications), the book reaches a climax. A subtitle for this chapter might be: General Chemistry From the Vantage Point of the Second Law. Developed there are those applications of thermodynamics mentioned in the first paragraph of this review. The hook contains a very generous set of well-thought out problems. Inclusion of answers to selected problems would probably increase the book's vdue to the student. Alan, while early in the book there is introduced the statement "The entropy of the universe increases," this statement is not fallowed up syatemeticrlly; indeed, the simple relation between the entropy change in the universe and the free energy change in s chemical system is nowhere mentioned. Furthermore, as is almost universal with textbooks on thermodynamics, there is conveyed the impression that the equilibrium condition for reactions occurring st constant volume and for reactions occurring at constant pressure are different; in fact, for a system that is in hydrostatic equilibrium with its surroundings, [ A ( E - TS)IT.V = [A(E - TS p V ) l r . ~ . In addition, the relation between a substance's activity and its partial molal entropy is not explored; one of thermodynamic's most useful applications, the explicit form of equilibrium constant expressions, is, therefore, not developed, but mumed. To be meaningful the early discussion of the relation between the conservation condition and state functions should include a comment on the distinction between intensive and extensive properties. The text sometimes does not follow the recommendstions of a recent letter in Sciace on "I, We, One, and Preaently." On the whole, however, thisis avery well executed hook, tbe best of its kind the reviewer has seen. Teachers of general
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Gordon M. Barrow, Case Institute of Technology, Cleveland, Ohio. W. A. Benjamin, Inc., New Yark, 1963. xi 156 pp. Figs. and tables. 14 X 21 em. Paperbound. $1.95.
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Few studies have contributed more to the advancement of physical science than have studies of the interaction of radiation with matter. From the early contributions of X-ray spectroscopy t o our understanding of atomic structure and the periodic table through the common dayto-day uses of the absorption of visible light by colored compounds to the recent socurate determinations of molecular parameters by microwave speotroscopy, the interaction of radiation with matter haa been an important tool in the study of the structure of matter. Today with the introduction of spectrometers in increasing numbers and variety into chemical laboratories, very notably into undergraduate teaching laboboretories, the appearance of a book on molecular spectroscopy at the beginner&' level is timely . indeed. The book's title, "The Structure of Molecules," is somewhat misleading. Its contents are more aceuratdy described by the subtitle. More than half the book is concerned with the rotational and vibrational spectre of diatomic molecules; only one page, per se, is devoted to the geometrical shapes of molecules. The book is divided into six chantelm. I n the first chapter the reader is intr&uced in eighteen densely packed pages of text to the wave nature of radiation, the quantum nature of radiation (18 lines), Planck's relation, the electromagnetic spectrum, methods of measuring the absorption of radiation (sources, dispersing elements, detectors, choppers, and doublebeam operation), degrees of freedom (tmnslrttional, rotational, vibrationd, and electronic), quantum restrictions, and Boltzmann's relation. , - . cdculation of the internuclear sepa%tion i n carbon monoxide from the moleculz's
vihretiand spectrum of carbon monoxide and the determination therefrom of its farce constant. In none of the chapters of this book is a knowledge of calculus required. (It is assumed, however, that the reader is familiar with the meaning of "erg," "dyne," and "f = ma!') (Continued on page A501
