Leonard K. Nash Harvard University Cambridge. Massachusens 02138
Reflections on Freshman Chemistry
The college freshman chemistry course, and even to some extent the high-school chemistry course, have in the last 15 years progressively shifted from general chemistry toward elementary physical chemistry. Examination of representative collections of textbooks in use a t the beginning and end of this oericd indicates that the shift has eone far toward comdetion. ~ a v i long n ~ urged the desirability of just such a shift, the writer is today less elated than dismayed by what has happened. Of course, the general chemistry of yesteryear would not properly exploit the amply demonstrated ability of today's college freshmen to handle material far more challenging than was offered them in the past. The physico-chemical material that has found its way into today's freshman course is amply challenging. But the introduction of a host of sophisticated abstractions seems wholly to have eclipsed phenomenal content. That's an unmitigated disaster for chemical pedagogy. For surely chemistry isn't about such abstractions as entropy and wave functions. Chemistry is about phenomena of qualitative change, and this we forget only a t grave cost to the color and excitement of our subject. No derogation of the interest and value of abstract theories is intended. With the Baconian conceot of tabula rasa now thoroughly discredited, today one understands that theoretical concepts are indispensahle in setting a horizon of expectation against which empirical novelty first stands out as something surprising, and so worth noticing.' Moreover, it is characteristic of an advanced science that a handful of theoretical eeneralizations stand in lieu of myriad observational particurars. Danger arises only when obsession with theoretical abstractions denies DroDer attention to the phenomenal specifics in which those al;stractions are rooted, b$ which they are secured, and throuah which they will ultimately come to he extended. Today much in fashion, a lavish use of mathematical abstractions seems a widely accredited mark of scientific sophistication. Yet biology has long been a science without being conspicuously mathematical, while astrology has long been conspicuously mathematical without being a t all a science. Perhaps our deference to mathematics is a remote consequence of Dirac's celebrated claim that, through his quantum mechanics, all of chemistry is a t last "reduced in principle'' to mathematical physics. Certainly that hold assertion had an enormous impact in its day. Now, almost half a century later, one feels far less secure in one's understanding of what may be meant by "reduced to,"and one is overwhelmed by the realization that to say anything is possible in principle is quite as emohaticallv to say that it is not possible in practice. Chemistry remains, and presumably will long remain, a science too rich and complex to be fully caught in the web of mathematical physics. This is most conspicuously evident in biochemistry. But, much closer to home, one has learned from such discov&ies as the xenon fluorides that, however powerful in principle, the abstract theories of physical chemistry are insufficient instruments of discovery-even though they do provide, ex po.~tfacto, ample rationalizations for whatever has been established empirically. There are in our test tubes and vacuum lines more things than are dreamt of in our chemical ohilosonhv. , Proper attention to the phenomenal is not achieved simply bv a renewed emnhasis on descri~tivechemistrv. That seems t u lare moit tenrht.riquire n.; much as it bores their students. ;\nd, thouph painnl, the teacher need nut ftrel altoyether de-
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606 / Journal of Chemical Education
vastated if some of his students think silver chloride is a pale vellow-meen em-orouided that thev well know where to seek more accurate informatmn. IVhat is truly dewstaring is related but iruite different: the i)ossihilitv thar through our instruction students may cometo suppose that one need think of silver chloride as no more than an assemblage of nucleons and electrons obeying obscure but definitive physical laws. There's much more than that to silver chloride (e.g., in its well-known association with gelatin) even as there's far more to contemporary chemistry than can now be extracted from any such body of laws. Troubled by the dominance of the ahstract theoretical over the concrete empirical, one is further troubled by what appears a gross overvaluation of the quantitative a t the expense of the qualitative. Notwithstanding Kelvin's oft-repeated assertion that our knowledge is imperfect until we can express it mathematicallv. one cannot he unaware that matters mav be imperfectly uiderstood long after they've been correct6 exoressed mathematicallv. Even what mav a t first aonear . . a~ purely quantitative discipline like ionic equilibrium demands a aualitative insight2 for the solution of oroblems that are m&hematically tXvial. What is forbiddingly difficult here is certainlv not the solution of the appropriate eauation. or even .. . rn thr a r i t w long supposedl the setting up uf an equation. 'I'he cruci:tl difficultv is recuanition of the aualirati\.e nature of the system that comes in question. ~
. ..students can readilv" handle countless problems classified in a college-outline or oroblems book, or in Keller-plan units, and still be wholly unable to cope with comparable problems that are presented unclassified and in a neutral context. That the oivnral nroblem lies t h e r ~hewmes ahundantlv clear from the fact that students can readily handle co&tles; problems classified in a college-outline or problems book, or in Keller-plan units, and still be wholly unable to cope with comparable problems that are presented unclassified and in a neutral context. An appropriate qualitative identification of the problem is indispensable, if only to suggest the approximations that make a simple calculation possible. And the attempt to exdoit such approximations immediatelv reveals another aspect of the ovkiemphasis on the quantitative. Students too often believe that the essence of science is quantitative rigor, and find repugnant and even "unscientific" the very idea of approximations and simplifying assumptions. But one well knows that these are virtuallv unavoidable in -~anv quantitative argument about the "real world," and that the assumptions and approximations of ionic equilibrium are no different in kind but only more obvious in practice. What a ex~erienceoffers n o nrior examnles: .ojtv that the hi~h-school " e.g., the generally unvoiced assumption of volume additivity that underlies the classical mixture nrohlems of hieh-school algebra. ~
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American Chemical Society. I On the primacy of hypothesis, see Nash, L. K., "The Nature of the Natural Sciences," Little Brown, Boston, 1963, passim. On the unspecifiabilityof skills, see Palanyi, Michael, "Personal Knowledge," Routledge & Kegan Paul, London, 1958, p. 49 et seq.
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To he sure, the skill for making hack-of-the-envelope calculations on ionic equilibrium may he close to the brink of obsolescence. The advent of inexpensive proerammahle hand-held calculators should render .kperfluox &any of the simolifvine assumptions that students find so troublesome. B U here ~ we imp&e on a deeper and still less tractable problem: the ohsolescence of skills. Such ohsolescence is indeed amply obvious to older chemists who achieved a hardwon mastery of a hydrogen-sulfide scheme of qualitative analysis, the operation of a slide rule, and many other skills today quite equally without value. The obsolescence of skills is of course unavoidable, and positively delightfnl-in that it implies progress toward deeper knowledge and more powerful skills. But, this progress being abundantly demonstrable, it follows that students must be prepared to acquire new knowledge and new skills. We may even maintain that the only ability unquestionably worth teachine is the ahilitv to learn for oneself thines one hasn't we are abysmally ignorant of how to been taight. train students to learn for themselves. We might justifiably suppose that the laboratory offers the one obvious situation ~ e r f e c t l vsuited to such learnine. But not. alas. a lahoratorv that operates as most freshman chemistry l&ora&ries operatk today. Examining laboratory programs, one sees again the increasine dominance of quantitative over qualitative. Evervwhere in fashion, this dominance is in thk laboratory additionallv encouraged hv (1) the transfer to the freshman enterprise of responsibi%ties that helonged to quantitativeanalysis courses that seem now to be following qualitative analysis into oblivion; by (2) the current availability of inexpensive p H meters, spectrophotometers, and other powerful instruments; and, a t the most mundane hut not least influential level, because (3) quantitative determinations of unknowns provide an ostensible solution to the otherwise naggingly intractable problem of grading students in the laboratorv. That's no trivial ~ r o b l e mwhen one must run a large course with the aid of a corps of graduate teaching assistank, hut the need for a reasonahlv eradahle laboratory mav have an unreasonably large effect i n what students &e asked to undertake in the laboratory. Whatever may he the origin of emphasis on quantitative meter readings, and one thinks here of Eddington and his strange hut influential view of "objectivity," students today may pardonuhly believe that just those meter readings are u,hat the laboraton ianllabout. All tooseldom are thereacrual chmucal phenomena for them to look at. And there may then clnme the shock ot'recognition thar one's own carefully cunstrurted laboratnry curriculum faili to offer students thc slightest stimulus to close and careful ohsewation-perhaps including even observation of something not expected a priori. The problem is not a t all peculiar to chemistry, though surely less readily excusable in chemistry. Hear a distinguished modern physicist who, as a general lesson, emphasizes"
ow ever,
. . . the importance of qualitative observations-what
we may describe
as looking for the natural history of the phenomenon. This aspect of practical physics has always been soft-pedalled. Yet it is the intuitive feeling for what can and cannot happen that is the mark of the sound
scientist, and this feeling is not developed hy concentration on the laws and their exact application; in addition there must be a fascination far, a deep involvement in, all the marvellously complicated things that can happen, that are worth looking at and speculating about even though one knows an exact analysis is not practicable. It is this side of a scientist's life, I am sure, that is the spring of his imaginative originality,and by neglecting to develop it we are losing
it to just looking at and playing with things, and writing reasoned accounts of what they have seen and learnt? We should, incidentally, do more than just produce better physicists. The art of observing and
descrihing is one which has application in everyday activities far outside the normal traffic of physics, and teaching of this sort can genuinely be described as sound general education, with the peculiar advantaee of heine tied to a orofessional need so that the committed
being. How refreshine is the early reference to "natural history" in
Our freshman laboratories leave too little room for wonder and surprise, produce too little sense of what one can discover for oneself. an archaically non-pejorative sense! And how bold the terminal claim, to which we return in closing. Our freshman chemistrv laboratories leave too little room .-- -for wonder and surprise, produce too little sense of what one can discover for oneself. For many years the situation has been openly scandalous, but one sees little disposition to act on such nossihilities as Pippard's further sueeestion that the lahora-tory should include .. . a wide variety of guessing games with the aim of developing insight into many different sorts of problem. [Tlheproblem would be stated to a small group, who would discuss it and produce in a given time their considered opinion. They would then do the necessary experiment and, helped by the class head, hold a postmortem. I believe this would be enjoyable as well as instructive, and enjoyment is an important element in godteaching. Unhappily, our valuation of the gain consequent to enjoyment is tempered by legitimate doubt as to the "gradability" of any exercise like that here proposed. May it be that we tolerate the palpable inadequacy of our freshman laboratory programs simply because, in our heart of hearts. we've alreadv conceded the obsolescence of the simple skills therein imparted? For one may well question the value of those traditional skills in an aee " when computer iuterfacing with powerful instruments may require, in the limit, no more than insertion of a sample and subsequent collection of a written report on its characteristics. Now if indeed the freshman laboratorv convevs onlv worthless skills, we ought not to deny that knowledge t o o & hard-pressed Deans. For think of the staeeerine costs of our laboratory promams! Apart from the pure1;fiscLexpeuses for building oveqhead; fo; instruments, chemicals, and supplies; for teaching-assistant salaries; there is the even less f&ivably extravagant cost of our students' time and effort. If the freshman laboratory simply cannot be made worthwhile, we owe it to everybody (and not least of all to ourselves) to say so loudly and clearly, and to act accordingly. When baldlv stated, the irredeemahility of the freshman chemistry l;ilr)~toryu4l he accepred hy feu,. Kven the simple skills therein acauirable retain their useiulness, it m l v as a means of detecting the manifold malfunctions of sophisticated instruments. Moreover, the whole instrument-computer approach presumes the qualitative possibilities fully definable a t the outset, and leaves too little scope for the unexpected qualitative manifestation that is the most frequent wellspring of important conceptual novelty. Such a phenomenon we can perceive only when both our ideas and our experiments are sufficiently open-ended to make such recognition possible. As to openness to experience. mav we not he denviue " .. our students the one mvit important lesson that can be roweyed through scienrc instructwn? Science is the on/>rfirctirr instrumrnt we possc~isto combar superstition. irratimnlism, ol,icur;mtism. The need conrinuouslv to iirht thar fight was not apparent for many years, but is inescapable today when not merely adolescents but adults as well are fully prepared ~
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3 Pippard, A. B., "Reconciling Physics with Reality," Cambridge University Press, England, 1972, pp. 12, 14,9-10.
Volume 53.Number 10, October 1976 / 607
to abandon reason in order to embrace notions more primitive, more credulous, more romantic. Witness the resurgence of \'elekwsky! Of course this sad retrogression has extended sorial roors, but our own invdvement seems rlear: the triumph aftcr triumph achicved with the aid of s~ientifiral~strarri#ms enwura8e.i acceptance ot'ahstractions as jizn~mll)legitimate. For one may well suppose oneself authorized to believe whatever one pleases now that science has found merit in all kinds of crazv (read: counter-intuitive) abstractions. This is merely possible but inevitable a disakrous &clusion-not when science fails to stress how its abstractions are anchored in experience. Our intellectual heritage lays on us the obligation to fight this fight. But if we wish to combat credulity and irrationalism, must we not ourselves set an example of responsibly critical thinking? If our students are to become percipent enough to see that "Power to the People" doesn't solve everyth:lng, must we not ourselves eschew, for example, the pretension that words like tend and tendency explain anything? If we reject the medieval concept of innate dispositions, must we not reject all use of "tend" and "tendency" to lend a statement of fact the wholly spurious appearance of an explanation? There is no tendency for electron transfers yielding closed shells, no tendency for entropy to increase, no tendency toward hybridization. One might as well claim to build an explanatory economics on the argument that the rich tend to get richer while, on the other hand, the poor have a tendency to get poorer. T o see a problem, to recognize one's own ignorance, demands courage and capacity to detect the emptiness
. ..anybodypersuaded to believe some of the nonsense we spout in freshman chemistry would believe anything. of facile pseudo-explanation. But, as it is, anybody persuaded to helieve some of the nonsense we spout in freshman chemistry would believe anything. Our presentation of abstractions must reflect not only critical thinkine but also. and m i t e as important. the characteristically scientific interplay of evidence and inference. Only thus is the abstract generalization rooted in concrete particulars; only thus does the conceptual ideal come to be defined as the limit of an explicit extrapolation from the empirically real. For example,though a truly reversible change is nowhere observable as such in the world of experience, reversihility is defined and meaningful as the limit of an extrapolation from the irre~ersihle.~ And the adequacy of the extrapolation as well as the value of the concept are documented by the success of calculations of the equilibrium condition in which alone a truly reversible change would in principle he realized. Awareness of such extrapolations offers the only possible justification for the way we play fast and loose with some experimental results. The conservation of mass is daily and universally violated in freshman chemistry laboratories, and is defensible onlv hv wav of an extraoolation. The more carefully the experiment is made, the &re narrowly do the results a .~.o r o a c hthe limit of an accurate conservation. And so we come to conventionalize the limit, and stubbornly to assert it as a orinci~le:even in the face of contradictorv findings we wholiy den; the status of facts. That is, contrary empirical findings aren't evidence against the conservation principle hut, rather, only evidence of experimental error. So also are most empirical findings that seem to contradict the law of definite proportions, or the supposed impossibility of spontaneous generation. If life appears in a supposedly sterile medium, that's not evidence supporting spontaneous generation, but merelv. a proof that the medium wasn't sterile. . Howewr, quite as rharacreristir as t h i ~ruiiv~ntionali~ation c g f principlri 1% the fact tllar in science such cun\.entionaliration is never absolute or final. Ultimately, revisions are possible. Not mass alone, but mass-energy is conserved; her-
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608 / Journal of Chemical Education
thollide compounds exist; and spontaneous generation.. . . Thus even long cherished theoretical principles do not escape the control of empirical data, and one concludes with Popper that what's most distinctive of an empirical science is not that it's verifiable but that it's falsifiable.5 One never knows one's right, hut may properly feel confident that error will o u t opening the wav to sounder ideas. - Newtonian inertia and Galilean free fall figure extrapolated ideals long defended in the face of almost universallv contradictoryempirical findjngs. But all such extrapolations t o ideal limits deserve more attention than we usuallv erant them. Galilee's extrapolation certainly isn't flawless: & the limit where the inclined plane becomes vertical, the rolling motion passes over into slide. This seems to have no un; toward consequences, hut similar carelessness faults other such extrapolations. Consider for example the extrapolation that terminates in the Gibbs paradox. Or the too-hasty extrapolation into the microcosm of our commonsense concepts of wave and particle. However dangerous, this last kind of extrapolation is inescapable in the creation of the metaphors, analogies, and/or models we need to construct our theories and even in order to make our observations: cf., Charles Darwin, "Without the making of theories I am convinced there would be no ohservation." Some baseline of "normality" estahlished by our concepts alone enables us to have percepts-of phenomena worth observing. Thus, a t a wholly pedestrian level, Boyle's law establishes a baseline relative to which we measure the deviations that characterize the nonideality of real gases. An interesting and significant case in its own right, Bovle's law is obviously a veryconsiderahle ahstraction&serted as a principle: deviations from Boyle's law we regularly dismiss as due to imperfection of the gas, not of the law. That is, we never admit that Boyle's law fails, hut only that we have mistakenlv ~ ~ l i ite to d a nonideal pas. Thus definine an ideal - a.. gas that nowhere exists, Boyle's law may seem to become an utterly sterile truth by definition. But look again! Consider the putative case of Nudnik, who asserts Nudnik's law: PV2 = constant. Nudnik's law admittedly fails with all real gases, but is said to apply rigorously to the Nudnikean ideal fluid it defmes. Now, long before the kinetic-molecular theorv. - Bovle's . law was accepted; and Nudnik's would have been an occasion for derision-and quite rightlv so. For where our experience of real gases otferinothin': k e n remotely like a ~u.dnikean ideal h i d , Buyle's law is at least appn)ximately applicable ro most gases at tnudest preusures, and rigorously applicable to all gasm in the e x t r . ~ p h r e dlimit of zero pressure. Hoyle's law is thus a significilnt scientific proposition, while Nudnik's is no more than an idle fancy. If we scoff a t Nudnik's law. do not some social fictions of comparable inanity deserve a like response? If a social ideal is not defined as the limit of an extrapolation from the real. i t is but an empty myth of some golden land beyond the ho: rizon. And that mav he a mvth not merelv futile but activelv malignant, in that'the foreordained faiiure of attempts actualize it leads ineluctablv to "idealism eone rotten2,-as when, in the name of peaEe and humanity, Weatherman zealots planted bombs in public places. In the end one cannot hut agree w ~ t hI'ippiird that imprwemenrs in elementary scienrr mstrucrion m ~ r h yield t not iust better ic~entist.;hut clearer-sighted humanheings. There's nothing earth-shaking about our present conclusion that improvement in freshman chemistry demands renewed emphasis on the phenomenal, the qualitative, the empirical. Their values are in principle acknowledged by everybody! Why then are those values so little represented in the design and content of our beginning chemistry courses?
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Eberhardt,W. H., J CHEM. EDUC., 41,483 (1964); 47,362 (1970); Nash, L. K., J. CHEM. EDUC., 47,357 (1970). Popper, K. R., "The Logic of SeientificDiseovery,"Hutchinson, London, 1959, passim.
