0
EXAMINATIONS I N THE PRACTICE OF ELEMENTARY ORGANIC CHEMISTRY G. ROSS ROBERTSON University of California, Los Angeles
DISS~TISFACTION
with conventional examination questions in organic chemistry has led to the commendable improvement recently prepared under the auspices of the American Council on Education and entitled "A. C. S. Cooperative Organic Chemistry Tests."' These tests offer a refreshing change from such items as "Give five reactions of aldehydes" and "Write equations for the synthesis of methyl orange" which have featured certain examinations of past years. Although the new multiple-choice questions constitute a searching inquiry into the student's knowledge of general organic reactions, in the writer's opinion they fall far short of identifying the thoughtful laboratory worker who knows what to do, how and when to do it, and why. This opinion hinges upon the assumption that there are three levels of chemical education, all important; furthermore, that the multiple-choice examination tests only the lower, or first two of the three levels. These levels are the following:
handbooks and any textbooks presenting theory only. Laboratory manuals and private notebooks are excluded. I n the case of the particular example cited, the laboratory course had already included complete, single synthetic experiments with acetic acid and derivatives, hydrolysis of an ester, aniline, acetanilide, diazotization and phenol, to say nothing of additional operations in which correct technique in extraction, xashing, evaporation, drying, introduction of acid and alkali, etc., were prescribed and disoussed. The restriction specifying acid hydrolysis was considered desirable in order to keep the procedures of the various students closely comparable. The instructor vho has never thrown his students on their own resources n+th such an examination has a revelation coming when he grades the papers. The wide variation, from intellectual daylight to darkness, will be something of a surprise. In the first place, the students who are comparatively illiterate in English composition-a significant number-get into trouble 1. Learning of chemical facts. 2. Understanding of the reasoning presented by promptly, and this is desirable. We hope that this fact instructor or textbook, and recitation of such reasoning will circulate among the students. On the other hand, back in an ~xamination~perhaps with "propyl" and certain able students who have not been stimulated by a "butyl" substituted for "methyl" and "ethyl" dis- mere memory course, but who are willing to indulge in some thinking as a ch~micalreaction proceeds, are cussed in class. 3. Selecting data m t suggested by the instructor and conspicuously revealed. Unfortunately, this type of examination is not suited using such data to solve a problem. of three or four hundred students vhose to a r~eiment .. It is this third and highest form of chemical training papers must be handled by a staff of teaching aswhich has led t o the use of the type of examination de- sistants or an ynternational" business machine. If scribed belov. It deals with the type of activity vhieh numbers are more reasonable, perhaps as many as 60 or progressive industry and worthy graduate schools 80, the one instructor grading the examination reads naturally favor. The examination is designed to dis- tach paper once, marking errors, apd places it in a tinguish laboratory thinkers from cookbook slaves. I t ranking position on the ample table spacp hefore him. consists of a one-hour, open-book test, in which there Perhaps 8 to 10 piles of papers may be the final result. is but one problem. The following is a representative ~t the end of the reading, marking and sorting pern = m n h as given t o a state-university class of average formance the instructor assigns to the successive piles, ability after four to eight months of semiveekly lahora- respectively, arbitrary numerical values from 90, 95, or tory practice: 100 at the top down to a generous 10 per cent a t the "Write exact directions, suited to a Person of your bottom, adjusting such values to suit a convenient class experience, for conversion of one-half mole of aceto-o- average. ~h~ ,\.,.iter chooses 60 for this average as a toluidide into pure '0-cresol and pure acetic acid in figure not lolv enough to discourage plodders, and not maximum yields, with use of acid hydrolysis as an es- high enough to obscure the records of the A-grade persential part of the process. Specify apparatus, quan- formers. tities, and concentrations of reagents, using molar As a variant of the plan, and particularly for use early quantities if convenient toavoid time-consuming weight in the course, an examination of this type may veil be calculations." devoted to mere isolation of pure compounds from a Students so examined are invited to bring chemical mixture of two to five ingredients. In such problems 1 DEDERING, E. F., AN^ OTHERS, A. C. S. T ~ s cooperstivc ~, the student is sometimes expected to recover all compounds, at other times to discard one or two as worthTest Service, 15 Amsterdam Ave.. New York 23, N. Y. 104
FEBRUARY, 1948 less. I t is of course convenient to include acidic, basic, and neutral compounds. To avoid evasions based on mere dependence upon fractional distillation, the examiner may well choose compounds of nearly the same boiling point. On one occasion a test of the "write directions" type of examination was made by having both professor and junior instructor run through the same set of papers independently. As a result, few differences were noted
in the ratings. The writer still remembers clearly how his junior colleague exclaimed over one paper, written by a student whom we had hitherto not recognized as outstanding. I t mas agreed, in the language of the junior colleague, that "this sounds like something right out of 'Organic Syntheses."' I t has been interesting to follow, in subsequent years, the research records'not only of this student, but of others who made good s h o ~ ings in sudi a laboratory examination.
M i o ~ oL e b T h e Chemistry of t h e Infinitely Small are oonrerved i n the L i l l i ~ ~ t i aworld n of t h e micro Laboratory. Here, in Gull Oil's micro lnborntory, fuels are lllsterials-nll 'rime, h n h l y r e d i n qoantilies of 0.0001 t o 0.00003 of an ounce. Speeisl mechanical micro knives are used t o take samples of airnost invisible stsins from plaes. Even the o o ~ p e rl e i t on s man's hand as result of touching a brass door knob oan be detected. T h e b a t t e r y of WJIS equipment dlorn is for t h e ~ a ~ i automatic d , determination of carbon, hydrogen, a n d nitrogen i n organic oompounda. \raterials are burned i n the m e t d l i c cylinders) giving f a r quicker results t h a n i n testing with normal-sired batches. furnaces ( t h e
