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S E W BOOKS Phyaical Chemistry of High Polymeric Systems. By H. MARKASO A . V. TOBOLSKY. xi +- 506 pp. New York: Intcrscience Publishers, Inc. Price: $6.50. The fact that this new edition contains 150 new pages, 56 new figures, and 13 new tables reflects the substantial increase in literature and advances in understanding of the physical chemistry of polymer systems in the ten years since the first edition of this work appeared. T h e new edition provides a n authoritative and up-to-date discussion of the chemical preparation of polymers, tho primary and secondary bonds in polymer systems, and the resulting influence on therniodynamic and kinematic properties of polymor solutions and the mechanical behavior of polymers. The book gives an extensive and thorough introduction t o the fundamental chemical and physical principles of major interest t o the polymer chemist or polymer physicist. I n view of the careful printing and excellent binding, this book will certainly he an important addition to the personal library of any acientist dealing with polymeric materials. CHARLESC. PRICE.
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Chemical Thermodynamics. By FREDERICK D . ROSSXNI. G x 9 in.; xix 514 pp. Kew York: John Wiley and Sons, Inc., 1950. Price: $6.00. This book contains a number of valuable features, some of which are given in the following list: (1) The discussion of empirical temperature scales, including that given by an ideal gas. ( 2 ) The relation between international and absolute joules and a discussion of the various thermochemical calories. (3) The calorimetric part of a thermochemical investigation. (4) The calculation of certain thermodynamic functions by methods of statistical mechanics. ( 6 ) The discussion of the third law of thermodynamics. (6) Applications to a system in a gravitational or magnetic or electric field. A number of teachers and students will find chapter 34 of great interest and value. The author discusses in some detail the thermodynamic study of ( I ) a mixture of ethylbenzene and the three xylenes, ( 8 ) the reactions involved in making toluene from the light gasoline fraction of petroleum, (3) the manufacture of “isooctane” for aviation fuel, ( 4 ) butadiene and styrene and other hydrocarbons used in obtaining synthetic rubber, and ( 6 ) the preparation of synthetic fuels and of synthetic alcohols. This chapter closes with a discussion of the evaluation of purity from measurements of the freezing point and a detailed treatment of fractionating processes. On the other hand, I find the treatment of the second law very unsatisfactory, on t h e whole. On page 69, the author writes, “For example, the increase in entropy in a reversible process might be defined aa d S = ap/f(T), where the value of f(T) increases with increase in temperature.” On page 70 he merely lets f ( T ) = T . Now up t o this point, at least, T is the temperature defined by an ideal gas. On page 71, the author remarks t h a t the second law “was first clearly enunciated by Clausius in 1850 and independently by Kelvin in 1851,” but he does not give their formulations. His statement of the second law is t o be gathered from the following remarks: ‘IAccording t o the second law, entropy is fully conserved over all systems in every reversible process. . . . If the process is not a reversible one, then, for all systems participating, the sum of all the changes in entropy is greater than zero.” This manner of stating the second law would be mare illuminating if accompanied by the following statements: (1) We postulate that the equation d S = aq/T for a reversible process defines S as a singlevalued function of the state of a system. ( 2 ) We postulate t h a t this function is conserved over all systems in every reversible process and that i t increases over all systems if the process is not reversible. Much later in the tcxt (on page 127) the author undertakes to prove “the identity of the scales of temperature provided by the ideal gas and by the second law.” He writes, “In earlier chapters, we introduced the absolute temperature by means of the definition of the ideal gas, and again independently by the second law of thermodynamics by the quantita-
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tive definition of change in entropy.” This seems t o mean t h a t the author considers it possible in one equation to define (that is, to give directions for measuring) two previously undefined functions, the entropy and a thermodynamic temperature. The author’s proof t h a t the temperature defined by an ideal gas is also a thermodynamic temperature will hardly be convincing t o his readers. I n paragraph 6 on page 5 we read, “The properties of a substance are classed as intensive or extensive, according t o whether the given property is independent of or dependent on the mass of the substance.” Although this definition is good enough for a phase consisting of one substance, it is not, in general, valid for a phase containing two or more substances. I n fact, as far as I have examined his text, the author gives no definition of intensive and extensive properties of a solution. although, of course, he gives examples of each kind of property. Chapter 24 is entitled “Solutions; Partial Molal and Apparent Molal Quantities.” The student will find in this chapter many helpful hints in the use of the “two basic partial molal equations” in the study of solutions. The derivation of these two basic equations leaves much t o be desired. On page 261, we read that “the composition of a solution may be specified by giving the number of moles of each component.” I n the next paragraph we read t h a t “the foregoing method specifies both the composition and the quantity of the components, the latter an extensive property. It is usually more convenient t o specify the composition separately as an intensive property,” using mole fractions. With this notion about “composition” in mind, we turn t o page 266 and find, “The change in the value of any property G of any solution is, a t constant pressure and temperature, a function of the composition only, and may be expressed mathematically as
dG =
(E)
nj
dni .”
S o w I feel sure that in this statement the author had in mind “any extensive property G” and not “any property G” and moreover t h a t he meant t o say that G is a function of all the mole numbers and not of the “composition.” This is, however, a minor matter compared with the lack of a satisfactory definition of a n extensive property. The integration of the preceding equation at constant temperature and pressure and constant composition t o give the first basic partial molal equation,
is not justified, since it has not been proved that aG/ani is a function of the composition only a t constant temperature and pressure. What is needed is not merely the statement t h a t G is a function of the mole numbers but the proof that it is a homogeneous function of the first degree in the mole numbers. It is then easily shown that any partial derivative of the form aG/an, is a homogeneous function of the zeroth degree in the mole numbers and therefore is a function of the “composition” only, apart from T and p . On page 123, in listing the criteria of equilibrium, the author omits the one that seems t o follow most directly from the second law: namely, the entropy of a system maintained at constant energy and constant volume attains a maximum value when a state of equilibrium is reached. On page 110, i t is stated that “Einstein showed t h a t the average energy (kinetic plus potential) of an oscillator vibrating with a characteristic frequency Y was t o be taken, not
kTx
-.” .4s a matter of fact, Einstein e‘ - 1 merely took over a result which is due t o Max Planck. On page 12 we have the peculiar statement that “in his derivation Debye modified Einstein’s procedure by letting (sic) each oscillator vibrate with all possible frequencies from zero up t o a maximum frequency, as kT for each degree of vibrational freedom, but as
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vnlS, characteristic for each substance.” The number of different frequencies available a t any time to all of the oscillators of the substance is finite and not infinite. It is, of course, difficult or even impossible to devise a simple system of notation for thcrmodynamic quantities. Some of the symbols used by the author seem bound to lead to confusion or misunderstanding. For example, on page 429 we meet with such symbols as A H f t and Kf.The di5erence between a small circle used as superscript and an oval zero used as subscript can be shown in printing, but it must be much more difficult to indicate the difference in speech or in writing on the blackboard. Moreover, the symbol Kf a t first glance will denote the product of K and f, whereas in the author’s notation it means the equilibrium constant of the reaction in which a compound is formed from its elements. I t seems t o me also that some less awkward expression than “the pV work energy” could be found for the term P d V or its integral. The sensitive reader will probably be irritated by the frequent occurrence of the locution, “That is to say.” The level of style attained by the author may be gauged by reading the following excerpts: “A thermodynamic process constitutes the changes which take place in the system or systems being subjected to thermodynamic study.” (page 5 ) . “With the final state B being identical with the initial state A, .” (page 37). “In the examination of the purity of the chemical reaction being studied. . ” (page 146). “In 1906, Nernst pronounced his famous heat theorem.” (page 213). F. H . MACDCJUGALL.
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The Physical Chemistry of Electrolytic Solutions. Second edition. By HERBERTS . HARNED AND BENTON B. OWEN.6# x lot in.; xxxvi 645 pp. New York: Reinhold Publishing Corporation, 1950. Price: tl0.W. Ever since its first publication in 1943, this treatise by Harned and Owen has enjoyed the greatest esteem. It has been an indispensable book for all chemists who are interested in the study of electrolytic solutions. The authors state in the preface that “in view of the expense entailed in a thoroughgoing revision of the original text, a compromise has been adopted in preparing a second edition of this work. An appendix has been added which contains revisions of the tables of the theoretical functions, extensions of some of the tables of data, and discussions of some recent experimental and theoretical contributions.” The second edition is, accordingly, a reprint of the first, with the addition of 37 pages of new material (Appendix B ) . I suggest that this Appendix B should be made available as a separate publication to those who already have acccss to the first edition. I might amplify the statement made in the preface to the second edition about the new appendix by listing some of the topics included therein. These are, for example, “Diffusion Coefficients of Potassium Chloride and Calcium Chloride in Dilute Aqueous Solutions,” “Summary of Recent Contributions to Theories of Electrolytes,” “Dissociation of Strong Electrolytes as Derived from Raman Spectra,” “Dissociation of Some Moderately Strong Electrolytes,” “Ionization Constants and Ionization of Weak Acids in Salt Solutions,” and “Transition from the Simpler to Complex Aggregates and Polymer Electrolytes.” F. H . MACDOUGALL.
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