What Chemistry to Teach Engineers?

In the Classroom

What Chemistry to Teach Engineers? Stephen J. Hawkes Department of Chemistry, Oregon State University, Corvallis, OR 97331-4003; [email protected]

I have been studying chemistry for half a century and now know enough to know that I know only a little. When there is only a semester, or even a year, to teach chemistry to students, what part of my accumulated learning should I attempt to impart? What subjects with which I am uncomfortable should I master for their benefit? What means are available to make a decision? When I was young it was easy: I taught what was in the introductory texts in the naive belief that somebody had addressed the question and made an informed decision. I was wrong. In previous papers (1, 2) I have addressed the needs of students in disciplines mostly related to the life sciences, neglecting engineering. Here I address the particular needs of engineering students, which turn out to be similar but not identical. Only a little help is given by the Accreditation Board for Engineering and Technology, some more by study of engineering textbooks, some by study of the texts of other required subjects to detect overlap with chemistry, some by consultation with engineers. Accreditation The current curriculum for accreditation of an engineering program (3) requires that studies include “both general chemistry and calculus-based general physics…with at least a two-semester sequence of study in either area.” Almost all schools of engineering require a full year of physics (I checked 14 catalogs of engineering schools and found this true in every case) fulfilling the two-semester requirement, so that most students receive one semester of chemistry. It is clear that only a limited exposure to chemistry is demanded, but it is not even suggested what aspects of this vast subject are most useful to engineers. This work explores that question. The new curriculum “ABET2000” (4 ) is even less precise. It requires “one year of a combination of college level mathematics and basic sciences (some with experimental experience) appropriate to the discipline” (underlining is in the original). This does not specifically require chemistry as a general requirement for all engineers. However, ABET2000 lists separate curricula for each engineering program, which are summarized in Box 1. Many of these do not include chemistry. We may expect that college departments responsible for these programs will not include chemistry in their curriculum, and that the number specifying only one semester will increase. Laboratory Accreditation does not specifically require laboratory experience in chemistry. If a chemistry department goes to the trouble and expense of providing a chemistry lab for engineering students it does so for philosophical or political reasons unrelated to the students’ professional needs. The philosophical needs will be met at least in part by the laboratory requirement of the physics course, so the chemistry lab requires careful justification and great care to ensure that the alleged purpose is in fact achieved.

This Work The problem would be easier if there were a definite answer to the question “Why do engineers need to study chemistry?” but there isn’t. To find what chemistry is actually needed by engineers (other than chemical engineers), I worked my way through 38 engineering textbooks noting what chemistry was assumed and what chemistry was taught. This is summarized in Boxes 2–4. My findings have been submitted to both academic engineers and engineers in industry and to most of the authors I have quoted, so that they could correct naive conclusions. A few engineering texts open with a review of the chemistry needed. However, such summaries are more rigorous and more quantitative than is needed to understand the rest of the text or the professional problems that engineers face. That a concept is not used in the study of engineering does not necessarily mean that it should not be part of the education of an engineer. Engineers are also citizens and Box 1. Chemistry Requirements for Engineering Disciplines in the New Requirements “ABET2000” Programs with no chemistry requirement: Aerospace, Electrical, Engineering Management, Engineering Mechanics, Naval Architecture & Marine Engineering, Ocean, Petroleum, Surveying Programs specifying only the words “general chemistry”: Architectural, Civil, Construction, Environmentala , Geological, Industrial, Manufacturing,b Mining Programs with other specifications: Bioengineering. Requires “understanding of biology and physiology”. This will normally have extensive chemistry prerequisites. Ceramic. Requires “ability to apply advanced science [such as chemistry and physics]…to materials systems”. Chemical engineering. Requires “thorough grounding in chemistry and a working knowledge of advanced chemistry”. Materials & Metallurgical. Require “ability to apply advanced science [such as chemistry and physics]…to materials systems.” This may have chemistry prerequisites. Mechanical. Requires “knowledge of chemistry and calculusbased physics with depth in at least one”. Nuclear & Radiological. Require “ability to apply advanced… science…including atomic and nuclear physics, and the transport and interaction of radiation with matter, to nuclear and radiological systems and processes.” There would be only a small chemistry component in this, so these departments could elect to teach the chemistry themselves in only a few lectures. a Environmental also requires “a biological science”. This may have an organic chemistry prerequisite. bManufacturing also requires “proficiency in materials and manufacturing processes: understanding the behavior and properties of materials as they are altered or influenced by processing in manufacturing.” Courses that provide this training may include the necessary chemistry or may have chemistry prerequisites.

JChemEd.chem.wisc.edu • Vol. 77 No. 3 March 2000 • Journal of Chemical Education

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should know whatever chemistry it is considered that every citizen should know (1, 2). Chemistry That Is Taken for Granted Most of the chemistry needed by engineers is provided in the texts for the engineering courses assuming only an elementary exposure to chemistry that could be expected in a high school general science program. This is detailed in Box 2. The exception is adsorption, which is seldom mentioned in beginning texts, but is assumed by engineering texts. Sweeping Generalization As a sweeping generalization, engineers have most use for understanding how the chemistry of a substance affects its physical properties and less need for understanding of chemical reactions. The reactions that seem to be important are those with atmospheric oxygen, carbon dioxide, or water. Chemistry That Is Needed The chemistry actually needed for those engineering disciplines that specify a chemistry requirement is compiled in Boxes 2–4. However, a few subjects need further comment. Box 2. Chemistry That Is Taken for Granted Meaning of adsorption Meaning of a chemical equation Existence of ions Complexation of ionsa Meaning (but not theory) of covalence Meaning (but not mechanism) of catalysis Existence of local areas of electrical charge in neutral molecules Ability to understand the symbolism of organic structural formulas Organic compounds are oxidized by air to CO2 and H2O Crystals are orderly arrays of atoms, ions, or molecules Crystals have cleavage planes Elementary understanding of the structure of the atom, including the nucleus Nature of radioactivity Electrolysis of salts a Especially complexation of metal ions by chloride. Not complexation equilibria.

Box 4. Subjects Often Taught in Introductory Chemistry That Are Also Taught in Other Required Courses Ideal gas law and kinetic theory of gases (physics) Real gases (thermodynamics) Critical phenomena (thermodynamics) Thermodynamics (thermodynamics)a Atomic structure and radioactivity (physics: but not always) a There is little purpose in the elementary introduction to thermodynamics provided in first-year chemistry texts unless to show that the principles have application in fields other than engineering. Even then, Spencer has shown (19, 20) that the thermodynamics in first-year chemistry texts typically includes substantial errors, so that discussion of thermodynamics is best left to later courses by better informed teachers. If it is taught, then the student-oriented introduction advocated by Spencer et al. (21) is preferable to the usual treatment.

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Box 3. Subjects That Are Taught and Used in Engineering Texts and Also Taught in Introductory Chemistry Electroplating Interconversion of chemical and electrical energya Molecular structure of silicates and aluminates in rocks, clay, and soil Stabilization and destabilization of colloids by electrical effects, including the effect of ionic charges Theory of semiconductivity Oxidation/reduction caused by electrical potentials Molecular structure and density of ice and of liquid water Hydrophobicityb and water repellantsc Polarity of water and resulting solvent power for ions Hydrogen bonding Vapor pressure of liquid water and ice and the effect of temperaturec Water hardness Acid rain Henry’s lawd,e Qualitative discussion of colligative propertiesf Comprehension of structural organic formulas (but not alkane nomenclature) Recognition of organic functional groups Relative polarity of organic functional groupsg Structural isomerism (but not optical isomerism) Relation between density and the packing density and mass of atoms and moleculesh Calculating density from d = m/v h Usual valence of period 1 and groups 1 and 2 and the lighter elements of groups 3 through 7 Disruption of molecules and crystal lattices by ionizing particles Origin of atmospheric radon When to expect deviation from the ideal gas law Ion exchange, including the effect of the eluant; examples from soil chemistry and environmental cleanup pH as an arbitrary scale of the propensity of a solution to supply hydrogen ions i,j Absorption and emission of electromagnetic radiation Oxidation as reaction with oxygen, and occasionally as reaction with other oxidants a

I found this discussed in only one engineering text. More properly “hydrophobia”. c Other liquids seem to be unimportant. But emphasize that water is never repelled, but is prevented from wetting by forces within the water. Failure to dissolve in hydrocarbons is attributable to entropy, not enthalpy. d But not Raoult’s law. e Henry’s law is most used in environmental studies. f Calculation of changes due to colligative effects are not used in engineering education, but are sometimes taught in their textbooks. g Principally that C=O > C–O > C–H and that C≡N > C=N > C–N > C–H. Numerical values are not useful at this level. hDensity was understood long before arithmetic was invented. Cavemen knew that rock has a higher density than wood. It might be thought obvious that when two forms of the same substance have different densities, then the one with higher density has the atoms more closely packed; in my experience this is not obvious and exam questions that require this to be perceived are regarded as unfair. For a surprising number of students it is not even obvious that iron has a higher density than wood. The qualitative aspects of density are important in the study of crystals, which seem to be important to engineers. It may be necessary to explain how it is measured and to introduce d = m/v, but it should not dominate discussion of density. Exam questions should test comprehension more thoroughly than calculation. i The logarithmic relation is never used, even though pH is often defined using it. This reinforces the view expressed nearly half a century ago by MacInnes (17), one of the leading workers on the theory of pH in his time: “In possibly all but one case in a thousand, it is not necessary to consider the meaning of pH in terms of solution theory at all, but only to accept the numbers as a practical scale of acidity and alkalinity.” j There is no value in all the pH calculations to which we subject students. Hawkes (18) has discussed how pH can be presented without the mathematical infrastructure. b

Journal of Chemical Education • Vol. 77 No. 3 March 2000 • JChemEd.chem.wisc.edu

In the Classroom

Atomic and Molecular Structure (Other Than Nuclear) It is sufficient that electrons may migrate from one atom to another forming positive or negative ions, usually from metal to nonmetal atoms. Greater detail of atomic structure is seldom used. The formation of the covalent bond by the attraction of two nuclei for the same electrons and the resulting dipole are both important, but orbital theory or the concepts of hybridization, resonance, or sigma and pi bonding are not used, although they are occasionally described. Texts describing semiconductors use band theory to explain their level of conductivity and the effect of temperature on their conductivity. An enlightening discussion of the chemistry of semiconductors is given by Mangonon (5) in his Materials Selection for Engineering Design, but I have not found that it is used in any other part of the text. The section of the text titled “Performance and Materials Selection for Engineering Design” does not include anything on semiconductors. Moreover, the electrical engineering program has no chemistry requirement in the new ABET curriculum, so we may conclude that this is not important enough to be required in introductory chemistry, though it would be an interesting discretionary topic for some engineers, especially electrical engineers. Periodic Table The periodic table is used only to show the relation of metals, semimetals, and nonmetals. The term “rare earth” can probably not be explained without reference to the table. The periodic table therefore needs to be explained in much the way that Mendeleev would have explained it, without reference to s, p, d, f, and quantum numbers. If the teacher’s philosophy requires that the table be “explained”, it is simplest to “explain” it using ionization energies as described by Gillespie (6, 7 ). Stoichiometry Only the simplest stoichiometric calculations are ever used. However, since phrases like “basicity as CaCO3”, “acidity as SiO2”, or “sulfate as SO3” are used frequently in the engineering literature and in other real-world contexts, it would be useful to introduce problems phrased in this way. The important principles involve ratios of reagent masses to each other or to mass of product, the additivity of molarities, and dilution calculations. Limiting reagent calculations and empirical formula calculations appear to have no relevance, but may perhaps be useful to consolidate comprehension. However, empirical formula calculations are typically presented as algorithms that cannot be easily related to more general principles and are memorized uncomprehendingly, so they do not consolidate comprehension of stoichiometry. Several practicing engineers confirmed that they regularly use the mole concept. Specifically, nuclear engineers calculate the number of atoms of a particular element or isotope per unit volume of a material. Aspects That Are Explained but Not Used In this section I consider aspects that engineering texts find it desirable to explain but do not use anywhere in the text that explains them, and that are not used in any other text that I have examined.

Equilibrium Equilibrium is seldom mentioned. This is not so surprising as it seems to a chemist, because systems of interest to engineers almost never reach chemical equilibrium. Masters’s text Environmental Engineering and Science opens with three chapters of chemistry (suggesting that advanced students skip them), which (inter alia) explain and define Ka, Kb, Ksp, and Keq; but these terms are never used through the rest of the book. This is also unsurprising: introductory chemistry is not defined by what is valuable to students, but by what chemistry professors learned as first-year students. As an example of equilibrium it discusses the carbonic acid–carbonate system, but I have no opinion whether this is important. An example of the deceptive introduction of equilibrium constants is found in Sincero and Sincero (8), pp 42–43. The solubility of CaCO3 is calculated assuming that Ksp represents the only equilibrium involved. The answer is given to two significant figures even though the hydrolysis of the CO32᎑ ion causes a threefold error.1 I found no use of Ksp anywhere in the rest of the book, except as a measure of solubility; it would have been better to quote the solubility directly. Hawkes has found (9) that such solubility calculations in pure water are, on average, in error by a factor of 5 and that calculations of acid–base equilibria (10) are also astonishingly inaccurate. This section drew fire from several academic engineers who felt that the concept of equilibrium was an important aspect of chemistry. No case was made for the chapters of equilibrium calculations that are included in most introductory texts, so these should be omitted and the phenomenon of equilibrium treated qualitatively together with some superficial application of the law of mass action. The work of Lambeth and Robinson (11) makes it clear that the concept of equilibrium is often not understood by students who can plug numbers successfully into mass action expressions. Given the mathophilicity of engineering students, this is probably even more true for them than for the mathophobic. Polymers Many texts explain the molecular structures of polymers and show structural diagrams, but I have not seen that any use is made of this information. This sentence also drew fire from both academic engineers and engineers in industry. There is a general feeling that polymers are such important materials in modern engineering that an understanding of their chemistry is important. I was unable to get a suggestion of what aspects of polymer chemistry would be useful. My reading of their texts gave no direct insight, but the overall philosophy that emerged from all their literature suggests to me that engineers have use for an understanding of how the chemical structure of a polymer affects its physical properties such as its density, permeability, flexibility, and conductivity, its chemical stability, and its capacity for adsorbing films and being wetted by liquids. They should understand the susceptibility of condensation polymers to hydrolysis by basic solutions. The chemical stability of polytetrafluorethylene should be explained. They need professionally to discuss the attributes of a particular polymer to establish its usefulness for some specific purpose. They need to understand the meaning of “copolymer”, “vulcanization”, “linear”, “crosslinking”, and “condensation” and the differences among thermo


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sets, thermoplastics, and elastomers. Methods of synthesizing polymers are no more than marginally important to engineers. Our concern here is how much of this should be taught in introductory chemistry. The need for more discussion of polymers in courses for engineers was pointed out 18 years ago by Kybett (12). His discussion includes consideration of the tensile strength of polymers and how it is affected by the constitution, structure and lattice energy of the polymer. Engineering texts assume that a structural formula drawn for a polymer will be understood. It is therefore vital that students be introduced to enough organic chemistry to understand it. This is not much. The details of nomenclature of the alkanes on which I have wasted thousands of student hours is not needed for this, or for the biochemistry that is valuable to other disciplines. There should be some introduction to polymers in introductory chemistry if only to ensure that when students meet the more detailed study in materials science they will have the basic chemistry necessary to follow it.

Phase Diagrams Two texts showed phase diagrams of alloys. The phase diagram of the three common phases of water that is found in most introductory chemistry texts is found only in Shackelford (13) and in one engineering thermodynamics text and is never referred to again in either text. The relation between this diagram, whose coordinates are temperature and pressure, and the alloy phase diagram, of which the coordinates are composition and temperature, is not obvious to a neophyte, so the usual water diagram is more confusing than helpful. What They Should Know but Don’t It should be possible for chemists to introduce engineers to principles that they would find useful but that were not included in their training (see Box 5). This would require a more sophisticated dialog between chemists and engineers than is at all probable. One fragment that should be better understood is that two substances in physical contact invariably generate an electrical potential because the electron cloud is in a lower energy state on one than on the other. In the absence of a complete circuit the electron migration ceases after a millisecond or so as the charge builds up sufficiently to prevent it, but if the circuit is completed this “Volta potential” drives an electrical current, which may be substantial if both substances are conductors. This is a major cause of corrosion, since the less “noble” metal loses electrons and is converted to ions and ionic compounds (Bodner objects [14 ] that this is at best only a partial explanation; the rate of the resulting corrosion is also changed by the attachment of another metal).

Box 5. What They Should Know but Don’t Forces that cause adsorption Superficial understanding of effect of temperature and concentration on adsorption equilibria Volta potentials Pourbaix diagrams Organic molecules are usually only partially oxidized by environmental oxygen

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Corrosion is more easily understood with the aid of Pourbaix diagrams. I found, more than once, the assumption that organic materials are completely oxidized by environmental O2 to CO2 and H2O. It would probably be helpful for more engineers to be aware of the intermediate reaction products. For example, the oxidation of aliphatic hydrocarbons in gasoline or oil to produce aldehydes that spoil the odor and flavor of paraffin oil. Or the oxidation of linseed oil to the hard resin that is desired in oil-treated wood surfaces. Treatment of polluted water with air must surely leave it contaminated with such partial oxidation products. A section on bicarbonate buffering in one text explains that a buffer is a substance capable of neutralizing acid, and hence bicarbonate is a buffer. This explanation would not satisfy a chemist, and the context suggests that the author did not appreciate the importance of the conjugate acid in stabilizing pH, or perhaps considered it unimportant in the context of stabilizing bicarbonate lakes. Similar comments apply to the discussion of removing acids using basic aluminum salts. It would probably be useful to discuss what situations are conducive to adsorption. The relative strengths of London, dipole–dipole, dipole–induced dipole, hydrogen bond, electron donor–acceptor interactions and ion exchange would be described. The relation to temperature should be discussed only vaguely in such terms as “the fraction adsorbed is dependent on 1/T and the relation is roughly exponential”. The influence of pressure and partial pressure also merits semiquantitative discussion. Rigorous quantitative discussion is beyond the scope of introductory chemistry, while superficial discussion deceives more than it enlightens. Pseudo-first-order kinetics are important in environmental work where water or oxygen is a reactant. Environmental engineers should be able to calculate the extent of decay of pollutants and other solutes in water or air from their halflife or decay rate. First-Semester Chemistry Engineering students in schools that cannot offer special courses suited to their needs are often compelled to take the first semester of a one-year course. In this case the subject areas should be arranged so that the topics needed by engineers are treated in that first exposure. Specifically, the first semester should deal with crystal structure, with nuclear structure, with reduction and Volta potentials, elementary stoichiometry, and rudimentary organic chemistry. The more erudite aspects of bonding such as resonance and molecular orbitals, or the less basic aspects of stoichiometry such as limiting reactant and empirical formulae, can be left to the second semester. The spiral format used by Willamette University (15) is especially useful in coping with this problem. Some schools actually offer a one-semester course and several make it the only chemistry requirement for engineers. Such courses typically contain all the chemistry that engineers use. A few schools require a year of chemistry in addition to a year of physics, but in all such cases that I have seen there is no suitable one-semester course offered, and the one-year course is not spiraled. In these cases, exposure to the concepts of chemistry is spread over an entire year so the full year of chemistry is made necessary. Such schools could reduce the


In the Classroom

Box 6. Subjects Usually Taught in Introductory Chemistry for Which I Have Found No Professional Usefulness nature of the chemical bond: resonance, orbitals, quantum numbers,a π, σ, % ionic character Bohr atom pH calculations equilibrium calculations colligative properties calorimetry Hess’s law balancing equations work and free energy Nernst equationb partial pressures “descriptive” inorganic Arrhenius acid/base titrimetry X-ray diffraction atomic & ionic radii biochemistry c d metallurgy kinetic calculations crystal field theory most of organic chemistry paramagnetism Fahrenheit Graham’s laws bond energies electrochemical activity series ∆Hf and ∆Hc normality a The pointlessness of quantum numbers in introductory chemistry was discussed by Ruis (22) and has not been refuted in any reference that I have seen. It has been reemphasized by Gillespie et al. (23). b Failure to find a usefulness for the Nernst equation was the most surprising finding in this work. It is useful to specialists in corrosion but not to regular engineers. The simplification E = constant + (R T/nF ln 10) log(concentration) may be useful if ion-selective electrodes are discussed. c One engineer considered it important to know that organisms eat structures and fuels. d Kreyenbuhl and Atwood (24) found that engineers mostly agreed that metallurgy is of little importance in introductory chemistry, but I have received emphatic disagreement from an engineer whose views I respect.

demands of the pre-engineering curriculum by spiraling the chemistry course. Shackelford’s text Introduction to Materials Science for Engineers (12) includes all the material that an engineer would need and assumes only that the reader has the superficial acquaintance with chemistry possessed by students who have taken a general science course in high school. If a materialscience course is taken using this text without a prerequisite chemistry course, and the “Fundamentals” section is taken slowly and carefully, it should fulfill a chemistry requirement for accreditation as discussed above. It would certainly be better than taking only the first semester of an unspiralized one-year course. Sweeping Reform My reading of engineering texts suggests that they would profit more from study of the chemistry of materials than the study of much that is now taught in the introductory course, especially the course for majors. Specifically, the emphasis on the chemistry of solutions is misplaced, especially as the quantitative theory of solutions that is presented is so simplistic that it would be dangerous if it were applied. Further, the descriptive chemistry is usually irrelevant to the needs of engineers, or students in most other service courses. What to Leave Out Listing what is needed, and how needed subjects may be abbreviated or should be expanded, leaves the question of what is not needed for the professional studies of engineering

Box 7. Curriculum Changes Adopted by Owens and Springer Less time devoted to ideal gases Significant reduction in acid–base equilibria and calculations Less emphasis on nomenclature Greater reliance on laboratory activities to develop specific skills Elimination of combustion analysis problem solving No emphasis on multistep reaction mechanisms No coverage of wave functions, molecular orbitals, and ligand field theory Less emphasis on descriptive inorganic chemistry

students. There may well be other reasons for including subjects in the introductory curriculum that are traditional but for which the need has not been found in this study. I leave this with the philosophy of the reader. However, the subjects listed in Box 6 do not seem to be professionally needed, so if they are included in an introductory course, the teacher is obligated to defend their inclusion. Previous Findings by Owens and Springer The study of the chemistry curriculum for engineers by Owens and Springer (16 ) is especially useful because it approaches the same problem as this study using different criteria and reaches almost the same conclusions. A curriculum to include “modern topics” needed by West Point students required the authors to delete material to make room for it. They accomplished this by “first selecting the modern topics and then emphasizing the traditional subjects that were most relevant to these emerging areas. …This resulted in a number of changes” which are shown in Box 7. If There Is Time What would benefit an engineering student, although not basically necessary? The temptation is to teach material with which we are familiar, thus consolidating the traditional curriculum. If this trap is avoided, other criteria must be used. I have tried to avoid philosophy in this work, concentrating on what can be proved, but opinion must enter into this section. A few lectures on the structure of polymers and how the structure affects their physical properties would consolidate their understanding of structural formulas, intermolecular bonding as in nylon and cellulose, and the effect of entanglement and of the movement of small and large bond segments (i.e., of temperature) on the phase (glass, leather, plastic, elastomer, or liquid) of a polymer. Semiconductors are important to modern engineering and we may reasonably guess that they will become more so. Discussion of their chemistry will show the importance of crystal theory and will show that a more elaborate description of bonding is needed but is not supplied by molecular orbital theory. Whether to fill the gap by teaching band theory is a matter of opinion: there is the danger that this model will become standard and continue to be taught long after it is obsolete, but the theory does provide a useful conceptual model that combines the effect of temperature and the differences


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Box 8. Subjects Not Usually Taught in Introductory Chemistry, Which Should Perhaps Be Taught Supercritical phenomena Analytical chemistry a Structure and property correlations Fluid flow and viscosity aAnalytical chemistry was suggested by two knowledgeable correspondents, one of whom specified discussion of both its power and its weaknesses, and the effects of sampling, methods selection, validation, interferences, sensitivity, precision, and accuracy. These make sense intuitively, especially for environmental engineers, but no evidence or anecdotes were supplied to show that engineers are disadvantaged by lack of understanding of these.

among metals, conductors, semiconductors, and insulators, and the vague borderline between the last two, into one conceptual framework. However, introductory chemistry texts offer no reason why one band assists the movement of electrons through a solid while another does not or why an empty band assists this movement but not a full one. Better models may do this and may need to be taught. The mechanism of diffusion through solids and membranes and the dramatic dependence of diffusion rate on molecular diameter of small-molecule diffusants and on segmental motion in polymer diffusants seems important enough for inclusion. Engineers whose opinion I respect have suggested the three subject areas listed in Box 8. I have not found specific evidence for them, but I intuitively agree. Other Disciplines These findings are not very different from what was found in similar studies of other disciplines (see 1, 2). It may be concluded that the introductory chemistry curriculum needs drastic revision to meet the needs of introductory students, whatever their discipline. But… Several correspondents have commented on the narrowness of this study. The most succinct was “I submit that there are some chemical topics that are so intrinsically interesting and so beautiful that they should be taught, for their own sake if no other. I suspect that you might agree.” I do. The teacher must decide what is beautiful or interesting and will probably reach a conclusion that is different from mine. I consider that equilibrium calculations, pH calculations, and most of the models of the chemical bond are neither interesting nor beautiful. If they are included in the introductory curriculum it must be because they are useful. Usefulness is a pragmatic consideration and can be objectively defined. Since these subjects are not useful, they should be omitted except by teachers whose opinion on beauty and interest differs from mine. From my own opinionated viewpoint, biochemistry is interesting and nuclear science is beautiful, so both should be included. Other teachers will certainly disagree.

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Acknowledgment I am grateful to Prentice-Hall, Inc., for the gift of 14 of the engineering texts. Note 1. This same example with the same wrong answer is used in Kotz’s latest edition and also that of Masterton and Hurley. It is a sad commentary on our profession that we still produce teachers who believe this.

Literature Cited 1. Hawkes, S. J. J. Chem. Educ. 1989, 66, 831–832. 2. Hawkes, S. J. J. Chem. Educ. 1992, 69, 178–181. 3. 1993 ABET Accreditation Yearbook; Accreditation Board for Engineering and Technology: New York, 1993; p 62. 4. ABET Engineering Criteria 2000, 3rd ed.; Accreditation Board for Engineering and Technology Inc.: Baltimore, MD, 1997. 5. Mangonon, P. L. Materials Selection for Engineering Design; Prentice Hall: Upper Saddle River, NJ, 1999. 6. Gillespie, R. J. Atoms, Molecules and Reactions: An Introduction to Chemistry; Prentice Hall: New York, 1994. 7. Gillespie, R. J.; Spencer, J. N.; Moog, R. S. J. Chem. Educ. 1996, 73, 617–622. 8. Sincero, A. P.; Sincero, G. A. Environmental Engineering; Prentice Hall: Upper Saddle River, NJ, 1996. 9. Hawkes, S. J. CHEM13 News 1996, 250, 1. 10. Hawkes, S. J. Chem. Educator 1997, 1(6): S1430-4171; http://journals.springer-ny.com/chedr (accessed Jan 2000). 11. Lambeth, J. M.; Robinson, W. R. Presented at the 210th ACS Conference, Division of Chemical Education Section, Chicago, Aug 1995; CHED Newslett. 1995, Fall; Abstract 336. 12. Kybett, B. D. J. Chem. Educ. 1982, 59, 724–725. 13. Shackelford, J. F. Introduction to Materials Science for Engineers, 4th ed.; Prentice Hall: Upper Saddle River, NJ, 1996. 14. Bodner, G. M. Presented at the 211th ACS Conference, Division of Chemical Education Section, New Orleans, Mar 1996; CHED Newslett. 1996, Spring; Abstract 671. 15. Brink, C. P.; Goodney, D. E.; Hudak, N. J.; Silverstein, T. P. J. Chem. Educ. 1995, 72, 530–532. 16. Owens, P. M.; Springer, D. S. CHED Newslett. 1996, Fall, 67–68. 17. MacInnes, D. A. Science 1948, 108, 693. 18. Hawkes, S. J. J. Chem. Educ. 1994, 71, 747–749. 19. Spencer, J. N. Abstracts of 211th ACS National Meeting, New Orleans, 24–28 March 1966, Division of Chemical Education; Abstract 674. 20. Spencer, J. N. J. Chem. Educ. 1992, 69, 182–186. 21. Spencer, J. N.; Moog, R. S.; Gillespie, R. J. J. Chem. Educ. 1996, 73, 631–636. 22. Ruis, S. P. J. Chem. Educ. 1988, 65, 720. 23. Gillespie, R. J.; Spencer, J. N.; Moog, R. S. J. Chem. Educ. 1996, 73, 622–627. 24. Kreyenbuhl, J. A.; Atwood, C. H. J. Chem. Educ. 1991, 68, 914–918.


What Chemistry to Teach Engineers?

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