Martin A. Paul
Harpur College Slate University of N e w York Binghamfon and S. H. Bauer Cornell University Ithaca, N e w York
I Physical Chemistry in the Engineering Curriculum
Radical changes have been taking place since World War I1 in the education of engineering students. These are attributable to profound advances in scientific technology, comparable in scope to the revolutionary developments that took place a t the turn of the century. Hardly had we begun to assimilate the effects of widespread use of the lighter metals and synthetic plastics developed before the war, than we were faced with new developments: microwave physics had a revolutionary impact on communicsc tions; antibiotirs and synthetic pcsticides produced an equally dramatic impact on sanitation and health; jet propulsion changed the logistics of transportation and weaponry; nuclear physics transformed concepts of energy resources and military power; and computer technology is revolutionizing nearly every aspect of our lives. Life on earth appears not to be sufficiently complex for some of us; we are reaching out to the moon and stars. Engineering education had to change. The lead time between new discoveries in our research laboratories and their exploitation in technology has become so Presented a s part of the Symposium on Teaching of Physical Chemistry before joint sessions of the Divisions of Physical Chemistry and Chemical Education at the 148th National Me& ing of the American Chemical Society in Chicago, Illinois, August 1964.
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short that no technologically oriented curriculum call remain vitally useful to the graduates for a significant period. I n a short span of 20 years, commercial research enterprises were faced with the need for a complete turnover of their t,echnical staffs due to obsolescence. Progressive engineering schools have begun to emphasize studies of the fundamental disciplines in depth, inasmuch as the old divisions are no longer applicable to the conten~poraryworld. There are many aspects, however, which change slowly. The very terminology of engineering retains vestiges of the technological revolutions of the past. The first "engines" appear to have been military contrivances: battering rams, catapults, and the like. Plutarch tells how Archimedes almost beat off the Roman siege of Syracuse by means of his engines. As each new "secret weapon" was unveiled, the dismayed invaders would exclaim, "Here is Archimedes again!" The military engineers have inherited this tradition of being experts a t den~olitiou. I n contrast, the profession of civil engineering evolved from the peaceful application of the miltary engineer's craft; e.g., road building, water supply, and sanitation. With the advent of hydraulic and steam power during the eighteenth century, mechanical engineering developed into a profession. The scientific stature of nineteenth century engineering was high; the second Ph.D. degree awarded
in the United States in a scientific field was in engineering, and it went to Josiah Willard Gibbs a t Yale University in 1863.' The great electrical discoveries in the nineteenth century opened the way for electrical engineers, whose original concern was with dynamos, electric lighting, and transmission lines. The growth of industrial chemistry during the late nineteenth and early twentieth century brought about a ~eparat~ion of chemical engineers from chemists. These two groups have continued to maintain tolerably close ties and cordial relationships with each other, and in some universities continue to function in one department. During the years following World War I, the traditional branches of engineering were civil, mechanical, and electrical; chemical engineering occupied an indeterminate position somewhere between the engineering school and the chemistry department. With few exceptions these branches continued until the late 1940's. Since World War 11, engineering schools have responded to the challenge of the current technological explosion in a variety of ways. Some have retained the classical pattern. A few have adopted core programs with some specialization, offering a t the undergraduate level an unspecialized bachelor's degree in engineering. Other schools have organized more and more branches of engineering, some offering as many as 14 or 15 different engineering degrees. Besides the development of new branches of eugineering to cover the wide range of modern technology, there have been major changes in the curricula of all branches. Almost all engineering students are required to take courses in the applications of modern electronic digital and analog computers. Computer technology and communications technology have become major subdivisions of modern electrical engineering, and laser technology is rapidly expanding to the magnitude of an "opt,ion." Practically all engineering students, of whatever persuasion, are now required to take one or more courses in "materials science." This essentially new subject consists of the theoretical principles underlying the structure and properties of matter, part,iculasly in the condensed states. Some schools continue to offer as well a traditional course in materials testing, but many have abandoned this basically empirical subject in favor of a more sophisticated approach, using the full resources of modern chemical and physical theory. I n 1950-51 during a review of the 5-year engineering program at Coruell University, the basic courses in science were shuffled. Although the trends described above were not as clear then as they are now, Professor 1'. A. Long, then chairmanof the chemistry department, was asked by the engineering faculty to develop a course in physical chemistry for engineering students. The time available was a one-semester spot in the sophomore year. For several years Professor Long and Dr. John Bragg gave a three-hour course in the fall for some students and a two-hour course in the spring term for others. These lectures were then taken over by one of us (S. H. R.). No satisfactory textbook was available, since the conventional introductory texts are designed for one-year courses taken mainly by senior or junior undergraduates majoring in chemistry. WHEELER,L. P., "Josiah Willard Gibbs," Yale University Press, 1951.
The engineering students had comparatively slim experience in chemistry (one year of general chem~stry), but during the sophomore year they were about as familiar with mathematics, particularly with arithmetic computations and with calculus, as the general run of physical chemistry students were during the junior year.2 With the needs and background of these students in mind, a suitable textbook was prepared in mimeographed form. Examples and problems were included which would be meaningful to students with an interest in engineering; a t the same time the chemical substances mentioned were, so far as possible, those that are familiar to students with a limited linowledge of chemistry. Full advantage was taken of the fact that the students had taken courses in calculus and general physics. As it has turned out, the very features that made the book suitable for the engineering students are the ones required (in the present trend) to put physicalchemistry at an earlier position in the undergraduate program for chemistry majors (the junior or sophon~ore year). When the book was reviewed for possible publication, the decision was reached that with some additions it would be a suitable textbook for an introductory course in physical chemistry. In its published form the book thus covers appreciably more ground than can be treated in the one-semester three-hour course.8 At Cornell University, a thorough revision of the engineering curriculum (1961-62) set up a two-year basic science program with materials science offered to all engineering students as a four-credit-hour course during the first half of the junior year. The level of presentation is approximately that in "Physical Properties of Solid Materials" by C. Zwikker (Interscience Public* tions, Inc., New York, 1954), but greater emphasis is placed on the structures of solids and their correlation with properties. The course was first given in the fall of 1963 by Professor Arthur Ruoff and Professor Thor Rhodin of the Engineering School. Alultilith notes written by Professor Ruoff and Professor Rhodin, titled, "Introduction to Materials Science," are used as the text, which is firmly grounded on the supposition that the students have acquired familiarity with the principles and methods of introductory physical chemistry. An idea of the scope can be obtained from the following outline of major subjects covered during the one semester: Binding, Structure, and Chemical Constitution. Assemblies of Matter and Equilibrium. Rate Processes and Mechanisms. Metastable Structures. Mechanical Behavior of Materials.
The theoretical part of the course is accompanied by laboratory experiments which include X-ray diffraction studies of order-disorder phenomena, establishment of ¶This is no longer the case, since advanced mathematical techniques and concepts are being taught in the more progressive high schools. The incoming freshman specializing in science has considerably greater sophistication in mathematics then was expected as little as five years ago. 'The hook under discussion is PAUL,M. A,, "Physied Chemistry," D. C. Heath and Company, 1962. Professor George W. Murphy at the University of Oklahoma informs us that he covers this in a one-semester six-hour course given jointly to engineering and chemistry students. The chemistry students take further work in physical chemistry at a more advanced level (quantum chemistry, etc.). Volume 42, Number 4, April 1965
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phase diagrams by thern~al arrest and differential t,hernial analysis methods, n~icrographic examination of microstmctures in crvstalline materials., ex~erimental studies of dislocations and latt,ice vacancies, measurement of diffusion coefficients in solids, studies of thermal history effects on mechanical properties of alloys, and some open-euded experimeuts of a research nature on various mechanical properties of solids as related to structure. A second semester,. required of students in several . branches of engineering, covers surface properties, dielectric properties, electrical and thermal conductivity, semiconductors, magnet,ic properties, and superconductivitv. Since materials science is largely applied physical chemistry and solid state physics, much of the course if given without a physical chemistry prerequisite would have to be devoted to elementary physical chemistry at the expense of time talcen from the subject matter proper. Recognition of this fact led to a more receptive attitude on the part of the Engineering staff and students to the required physical chemistry course. The three-hour physical chemistry course was given for the first time to all engineers in the Spring of 1963 by Professor Ben Widom. In its second and third years it was supervised by Assistant Professor R. A. Scott.
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ter for a special two-term course (taken during their sophomore year) which is primarily physical chemistry ronibined with some lecture material and laboratory work in quantitative analysis. The objective of the one-term course is to present a rigorous treatment of selected basic principles, drawn maiuly from chemical thermodynamics and chemical kinetics. The quantum chemist,ry side of physical chemistry present,ly has much less to offer and, besides, demands a higher level of mathematical sophistication than is otherwise necessary. A t,ypical outline follow^:^ Conservation of energy (3 lectures): Internal energy concept (a function of two or more state variables); rigorous definitions of quantity of work and qnantity of heat; heat capacity, enthalpy, heats of phase changes. Gas laws (4 leotures): Temperature scales, the universal gas constant R, the ideal-gas equation of state and thermal properties, real gases. Kinetic theory of gases (6 lectures): Molec~~lsr velocities and the distribution lsw, experimentd demonstrations of the velocity laws, effusion methods of vapor-pressure determination, heat capacities of gases and the quantum theory, transport properties of gases, intermalecolitr forces.
The liquid and the solid states (4 lectures): Liquefaction, van der Wads' equation, vapor pressure; surface tension; dielectric properties; heat capacities of solids. Thermochemistry (4 lectures): Experimental thermochemistry; use of thermoohemical tables: chemical fuels.. . roo.ell ants, theoretical flame temoeratores. Equilibrium and the second law of thermodynamics (3 lectures): Entropy and Gibbs free energy. Simple phase equilibria (4 lectures): Clapeyron's equstion and its applications, semi-empirical vapor pressure equations, d o t r o p y (sulfur, tin, iron, carbon, etc.). 'Where adequate staff is available, we recommend that the course be given in two weekly lectures and one problem session (groups no larger than 18). The number of "lectures" given in the outline includes problem sessions.
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Physical properties of solutions (4 lectures): Partial vapor pressures, ideal solutions and nonideal solutions, distillation, boiling-paint and freezing-point laws. Chemical equilibrium ( 5 lectures): Equilibrium constants and use of standard free-energy tables, entropies of chemical reaction, the third law of thermodynamios and its applications. Phase diagrams for binary systems (4 lectures): Types of phase diagrams; alloys, order-disorder transitions, brass, steel, etc. Chemical kinetics (4 lectures): Simple rate laws snd their characteristics, activation energy and the concept of the transition state, theoretical analysis of rate processes.
During the semester a set of 4-6 problems is assigned every week. The testing usually includes three onehour examinations and a 21/2-ho~rfinal exam. Engineering is concerned with the exploitation of scientific knowledge to accomplish specific objectivesbuilding the Verrazano bridge and manufacturing penicillin are examples. The present explosion of scientific knowledge has greatly enlarged the variety of applications which the practicing engineer will be called upon to make. His education must be broadly based, so that he will be prepared to meet opportunities that are now only in the offing. Physical chemistry can contribute much to his understanding of what chemists have been doing, particularly in the area of correlating the physical behavior of materials with their chemical compositions and structures. In turn, familiarity with the engineer's use of chemical principles can help the physical chemistry instructor enrich the content of his courses. The course described in this report is one exploratory experiment for providing the avenue of mutual benefit.
