The USE of OBJECTIVE TESTS in
ORGANIC CHEMISTRY* ED. F. DEGERING
Pwdue University, Lafayette, Indiana
Tests in one form or another account for a large part of teaching routine. They are used as teaching tools to (1) stimulate the students to do a high grade of work, and (2) afford the instructor a means of rating the student with respect to his group. Most arguments in favor of tests can be resolved into one or the other of these basic concepts. I n tke writer's opinion, all tests may be classified as (1) dejkite or (2) indefinite. An illustration of the latter i s afforded by the discussion type of test. The definite type of test may be divided into ( 1 ) the blank page type, (2) the fill-in type, and (3) the objective type. Each of these has its justification, but the two latter seem to answer all the requirements for a test without placing a n undue burden on the instructor. Some statistics on the use of these tests are presented. The writer belimes that the most satisfactory test is the one that stimulates the student adequately without unnecessary taxation on the instructor's time.
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ESTS in one form or another account for a large part of teaching routine. They fall, according to one school of thought, into the category of necessary evils. To another group, tests serve as basic teaching tools.
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*Presented before the Division of Chemical Education at the Rochester meeting of the American Chemical Society, September 6, 1937.
It is beyond the scope of this paper to attempt to justify the use of tests. The writer assumes that the use of drills, quizzes, tests, or examinations of one type or another has been accepted by most instructors as a matter of routine. The basic question is not relative to the advisability of using tests as a teaching tool but, on the other hand, the type df a test that will most effectively and most economically attain the end in view. Most instructors will contend that examinations should aim a t a two-fold objective: they should stimulate the students to do a high grade of work, and they should afford a means of appraising the relative capacity of any given student with respect to the group. Various other arguments might be presented to substantiate the necessity of giving examinations, but they all resolve themselves into the problem of stimulating and placing a student. If this be true, then any type of test, that will stimulate a student to do high grade work and a t the same time afford a fair means by which the instructor may appraise that work, must be satisfactory. In the writer's opinion, all tests may be classified as (1) d e h i t e or (2) indefinite. In the latter group are those that deal in generalities and leave the student with little or no directions or guidance as in the discussion type of test.
TABLE1 (1) (2) (3) (4) (5)
The definite type of test may be divided, for the purpose of this discussion, into three subdivisions: the blank page type, the fill-in type, and the objective type. Such tests give the student a very definite idea of
THE DISCUSSION TYPEOB TEST Discuss the chemistry of the olefins. Discuss substitution in the benzene ring. Discus the industrial production of an organic compound. Discuss the chemistry of benzenediazonium chloride. Discuss the chemistry af the aliphatic alcohols.
TABLE3
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FILL-INTYPEGP DEFINITETEST (1) (a)Lactic acid heat ( 6 ) Glycine + h e a t (2) (a) 3-Hydroxypropanoic acid heat (b) 4-Hydroxybutanoic acid heat (3) ( a ) CHrHC:CHCO.OH HBr (b) Muconic acid 1 Br, (4) (a) Ammonium carbonate heat (b) Ethyl chlorocarbonate NH5 (5) Classify proteins. (6) (a) Give the xanthoproteic test for proteins. (b) What is the biuret reaction? (7) Give two methods for precipitating proteins (a) (6) (8) Show (a) acid and (6) ketonic hydrolysis of acetoacetate. (a) i bj (9) Indicate the alkyl halide needed in the acetoacetic ester synthesis to prepare (a) propionic acid and (b) 2-pentanone.
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A test of this type has a certain justification in that it permits the student to deliver according to his capacity to express himself clearly and forcibly. Obviously enough, the student with a thorough training in English
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TABLE2 BE BLANKPAGETYPE OF DEFINITETEST (1) Define (a) asymmetric carbon atom, (b) external compensation, (6) optical activity, (d) resolution, and (e) desmotropy. (2) State a commercial use for (a) phenol, (b) phthalic anhydride, (c) naphthalene, (d) nitrobenzene, and (c) tannin. (3) Give a commercial method far the preparation of (a) pyrogallol, (b) aniline, (c) benzenesulfonic acid, (d) Michler's ketone, and (c) phenol. (4) Give equations for five specific reactions of benzenesulfonyl chloride. (5) Starting with benzene, prepare (a) henzoic acid, (b) phenyl cyanide, (6) s-tribromoaniline, (d) m-nitromiline, and (e) o-nitrotoluene. (6) (a) Illustrate Sandmeyer's reaction. (b) What are auxochromes? (c) Is benzyl chloride more reactive than mchlorotoluene? (d) Distinguish between a m and diazo. (6) Illustrate the Friedel-Crafts reaction. (7) (a) Give the conditions for the substitution of chlorine in a side chain. (b) Indicate what happens when phenol is distilled over zinc dust. (c) Illustrate sulfanation. (d) Give the formula for the product formed by the treatment of aniline with acetyl chloride. (e) Starting with aniline, prepare p-nitroaniline. (8) (a) Give a test for protein. ( b ) Show the action of heat upon 3-hydroxyprapanoic acid. (c) Acrylic acid HBr -. (d) Give an equation for the preparation of salicylic acid by the Kolbe-Schmitt reaction. (e) 1Nitronaphthalene oxidation -. (9) Give equations t o illustrate five different type reactions of benzaldehyde. (10) (a) Illustrate a quinoid structure. (6) Give the equation for the reaction of benzoquinone with an excess of hydroxylamine. (c) Write the graphic formula for saccharin. (d) Give the formula and name of an aromatic alcohol. (e) CsHs.SO..ONa NaCN, fuse -.
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and composition has a distinct advantage over the student who may have a much broader edge of the field but is inadequately trained to express himself. In such an event. the discussion tvoe of test hecomes a measure of ability in composit~on rather than a measure of one's factual knowledge. In so far as the students are concerned, the good to be derived from this type of test might off-sit the ills. In so far as the instructor is concerned, such a test offers nothing but hard and tedious work. ~i~ of a student to a particular place in his group has been intensified by a large number of uncertainties and a certain degree of indefiniteness. As a result, an instructor who is faced with one hundred or more pafour or five discussion questions, . which deal will find himself tending to grade on quantity of material instead of quality of work.
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(a)
(6) (10) (a) How many monoethyl citrates would you predict? (b) How many diethyl citrates would you predict?
what he is expected to produce to give evidence of his familiarity with the subject. Usually his answer is right TABLE4 FILL-INTYPEOF DEFINITETEST In the blank space, give the answer to the question indicated a t the right. In the case of equations, give the principal organic product only. (1). . . . . . . . . . . . . . G i v e a commercial use for ethylene. (2). . . . . . . . . . . . . .G i v e a commercial use for acetylene. 3 ) . . . . . . . . . . . . G i v e a commercial use for ethyl ether. (4). . . . . . . . . . . . . . Name, CHa.CICCC12.CHz.CHs (5). . . . . . . . . . . . . . .Name, H1C:CCICBr2CH2.CH8 6 ) . . . . . . . . . . . Name, CHd20.0.CH2.CHI (7). . . . . . . . . . . . . . .Give a commercial preparation for acetone. (8).. . . . . . . . . . . . . H o w is glycerine prepared commercially? (9). . . . . . . . . . . . . . W r i t e the formula of 1,l.a-tribromo-2butene. (10). . . . . . . . . . . . . . Write the graphic formula for 1.2-ethanediol. (11). . . . . . . . . . . . . . W r i t e the formula for 2-chloro-3-pentanone. (12). . . . . . . . . . . ..Acetaldehyde nascent hydrogen (131.. . . . . . . . . . . . . . . . C H ~ C H T O H PCI, (14). . . . . . . . . . . . . . .3-Pentanone nascent hydrogen
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E~,NH/H,O? , (17). . . . . . . . . . . . . .W h i c h i s the more basic. NH3/Hx0 or Et3~/H10? (18). . . . . . . . . . . . . . .Ethyl bromide NaOH, ale. (19). . . . . . . . . . . . . ..Ethyl bromide NaOH, aq. (20). ............. .1,2-Dibromobutane f zinc dust/(Et.OHAc.OH) (21). . . . . . . . . . . . . ..1,1,2,2-~etrabromobutan zinc dust/ (Et.OH-Ac.0~) (22). . . . . . . . . . . . . . .Propane burning (23). . . . . . . . . . . . . . . Butanal burning (24),. . . . . . . . . . . . . . H , ~ : C H cH, , + HBr + (25). . . . . . . . . . . . . . .CHrCO.CI CH..CO.O.Na ~
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TABLE5 OF DERINITE TEST. O B J E ~ I VTYPE E
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Encircle the T if the statement is true, the F if it is false. T F (1) R.CH(NH&CO.OH NaOH, aq. RCH(NHa)CO.ONa HzO. T F (2) Ammonia is last when a 4-amino acid is heated. T F (3) Proteins are amphoteric. T F (4) A metallic cyanide a mineral acid as H&Ol- methanenitrile. T F (5) The hydrolysis of a carbylamine yields the corresponding acid. T F (6) I n the arc process, Na Hn,heat, pressure NHa. T F (7) A carbylamine R.MgX, then H.0 an aldehyde an amine. T F (8) The Nitride Process: 3 Mg N*, heat MgaNs, then 6 8 0 2 NH3 3 Mg(OH)*. T F (9) H O C N CIa C1.CN HOCI. T F (10) Fulminic acid and its derivatives are stable compounds. B. I n the blank, fill in the number of the corresponding name or formula. ...... (1) Aminoethanoic acid (1) (CI.CN)r (11) Glycine . . . . . . (2) Cyanamide (2) Methyl isocyanide (12) H S N C N ...... (3) Cyanic acid (3) HO.NC (13) HnN.CO.N& ...... (4) Cyanogen (4) Guanidine (14) CHVCHVNC . . . . . . (5) Cranogen chloride (5) N C C N (15) H.N:C:O ...... (6) Cyanuric chloride (6) Hydrogen chloride . . . . . . (7) Ethanenitrile (7) Urea ...... (8) Fulminic a d d (8) H O C N ...... (9) Methanenitrile (9) Methyl cyanide . . . . . .(10) Methylcarbylamine (10) CICN C. Complete the following (give organic products first): (1) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .R.CHX.CO.OH 3 NHs(2) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Above product CuSO,, aq. (3). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ..Product from 2 HIS, aq. + (4). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . a r e identified by the carbylamine test. (5) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R.CN 2HX-t (6). ............................................................ a r e the building units of the proteins. (7). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . R.CN + ( R C O ) s O + (8)............................................................ .is the tautomeric form of hydrogen cyanide. (9). ........................................................... .R.NC HgO (10). ........................................................... . C a C N1, heat D. I n the blank, place the number of the product that applies: ...... (1) CHVCN CHrMgI, then H20/(H+) (1) Acetamide (11) Glycine ...... (2) Cyanogen chloride ammonia (2) Acetone (12) Propylamine ...... (3) Hydrogen cyanide x H/(Na/EtOH) (3) 2-Aminopropanoic acid (13) 2-Butanone . . . . . . (4) Ammonium oxalate P*Oo,heat (4) Cyanamide (14) Pmpanamide ...... (5) CHVCHOHCN NH,, then H.O/(H+) (5) Cyanogen (15) Formamide ...... (6) Ammonium ethanoate PzOs,distil (6) Ethanenitrile ...... (7) Acetonitrile HlO/(conc. HBO,) (7) Ethylamine ...... (8) Methyl chloride sodium cyanide (8) Ethylcarbylamine ...... (9) Urea sulfuryl chloride (9) Fulminic acid ..... . ( l o ) Ethyl bromide silver cyanide (10) Methyl amine E. I n the blank, place the number of the reagent that applies: (1) Ethanal- 2-hydroxypropanenitrile (1) NHa (11) PxOe (2) Ethanenitrile ethanethioamide (2) H C N (12) NaOH (3) Ethylamine ethylcarbylamine (3) H10 (13) CHCb/NaOH (4) Hydrogen cyanide cyanogen chloride (4) x H20/(H+) (14) NaOH/Et.OH (5) Propylcarbylamine GHvN:C:S (5) Na (15) KC1 ...... (6) Mercuric cyanide cyanogen (6) Heat (7) Cyanogen oxalic acid ( 7 ) Cl* (8) Mercury -mercuric fulminate (8)H S (9) 3-Aminobutanoic acid Zbutenoic acid (9) conc. HNOI, then Et.OH ......(10) Methylcarbylamine methanoic acid (10) s A.
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or wrong; there is little or no opportunity for hedging. the student's ability thus obtained. The broader and The instructor, however, often does experience difficulty the more comprehensive the test, the more accurate in finding the answer due to the fact that students the instructor's appraisal of a student. The instructor, normally exhibit very poor capacity for organizing their on the other hand, can grade his papers in approximaterial. Out of a hundred such test papers, there mately one fourth of the time that would be required for might be a dozen that would be written in such a the blank page type of definite test, without sacrificing manner that the instructor would actually enjoy read- any of the benefits to be derived by a student from a ing them. test. Tests of this type are time saving on the part of both . This represents an extension of the idea utilized in the student and the instructor. For a given time, much the last type of test. It has certain advantages in that more material can be covered and a better measure of all of the answers are to be found on the left hand mar-
gin of the page with the net result that the instructor finds himself conserving his time in so far as the grading of papers is concerned. Theobjective typeof definite test is shown in Table 5. Such a test permits one to cover a maximum amount of material in a given time, and permits a distinct approach a t a measure of the student's capacity. Students do not do equally well on the different parts of this test. Some do unusually well on one particular part of the test and quite poorly on another part of the test. In so far as the instructor is concerned, the grading is reduced to a minimum. The writer knows of a t least one professor who supplies his daughter with pin money by hiring her to grade his objective tests. A rather limited study was made of the response of students to the last two types of tests as judged by their grades, and the results of that study are shown in Table 6. It seems more or less conclusive from a consideration of this data that students do about as well on one type of test as on another type of test. The writer is quite
fully convinced that any test that will stimulate the student to do his best work is satisfactory in so far as
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ObjectiveTests (Type 0,Table 5) us. CompletionTests (Type C. Table 41
Type 0 Type C
Told Aoerage Average Tie Fint Semester Chemical Engineers 92 Home Economics 100 Agriculture 210 Second Semester Chemical Engineers 93 Home Economics 72 Agriculture 184
39.5 31.7 30.1
36.1 32.0 35.1
8 6 6
63 out of 92 39 out of 100 39 out of 210
38.0 32.8 32.9
36.5 31.2 38.2
6 7 7
54 out of 93 45 out of 72 25 out of 184
the student is concerned. As to the instructor, the type of test that makes the least possible demand on his time and energy, provided it stimulates the students to study, is the most satisfactory.
