Sidney Siggia
University of Massachusetts Amherst, 01003
A Third Dimension in the Teaching of Analytical Chemistry Real problems replace recipes
Theory and techniques have bee11 the principal dimensions in the teaching of analytical chemistry. Needless to say, they are mainstays in the field. However, there is a third dimension which is equally important in the training of analytical chemists; this dimension is anal&cal thinking. Theory gives thr student the basis of all analyt,ical measuring approaches; techniques give him the manipulations necessary t'o oh-tain good data; analytical thinking enables the st,udent, to attack problems efficient,ly and conclusively using both theory and techniques. The scope of modern analytical chemistry is broad. The well-rounded analytical chemist must not only have a firm understanding of inorganic and organic! rhemist.ry, but he must also have an understanding of physical and physical chemical phenomena. In "analytical thinking," the thought processes must tie toget,her all these facets toward one goal: the solution of the pmblem a t hand. The "problem" thus hecomes the forus of all attention in chemical malysis. Can we teach analytical thinking? The answer is that we cannot. I t is a t,hnught process and each individual has varying thought processes. However, wc can exercise the student's individual thought processes by continually exposing him to real analytical problems during the course of his education. In this way, not only are the theory and techniques transmitted, bnt these are continually orientd toward goals. At the Undergraduate Level
The author has injected the dimension of anal?;t,ical thinking into the analytical rurriculum at the rmdergraduate level by several techniques: (1) using commercial products as unknowns; (2) requiring answers that are more than percentages of composition; (3) giving a minimum of analytical details and expecting the student to garner the remainder; and (4) continual orienting of the theoretical and descriptive lecture material toward the focal poin-the analytical problem and its solution. The use of commercial products as unknowns has several advantages. The student is faced with real situations which not only exercise his thinking hut which also arouse interest in his work. These are "live" problems which are connected with his everyday living. This stimulation adds incent,ive and this incentive improves his assimilation of all material presented to him. The following types of laboratory problems are itlustrative; the analytical technology heing demonstrat,ed is in parentheses.
Aasuming Ivmy soap ta be Y944/m% pure, what is the equlvxlent weight of the soap used therein (nonaqueous acid-base titrimetry)? Hrrw mnch manganese is there in steel (calorimetry)? Ajaz, Babbo, and Comet all advertise the bleaching power of their kitohen oleansem. Determine the oxidizing power of each ~ n d knowing , the cost of each, determine the oxidizing power per penny( iodimetry).
How much ethylene glycol is there in an rtutamobile cooling system (oxidation-reduction)? How low in temperature will thia glycol content go as an anti-freeee?
There are many commercially available "unknowns" and, in many cases, analyses of these products are availn,hle on the parkage or from the manufacturer. H o w ever, the student should he graded not only by the final numerical value he obtains but by demonstration of his comprehension of the experiment as evidenced in his written report and in verbal examination in lab. The important thing is that the student learn the material and exercise his thinking. The reality of the situation enlivens t,he student's interest and also makes the mat,erial t;aught, him part. of life and not just "t.extbook stuff." The discussion above also illustrates technique (3) ahove---requiring inform~tion ot,her than just per(-entages. The t,hird technique is the use of minimum detail in lahorat,ory experiment instructions. All professors who want t,heir students to hecome genuine ana1yst.s have always objected to t.he "recipe" type instmct,ions given t,o st,udents. Almost anyone who can read ran follow such instructions. Obviously, however, the student cannot be left completely on his own, since his hackgnnmd is limited. It is our practice to omit from the instruct,ions the sample size required but the student is told the number of significant figures required in the result, and is given the approximate range of composition of his sample. The chemical reaction involved in the analysis is omitted, and i~alculationsare not described. Reagents are specified, hut directions for preparation and standardization are omitted. The student must statistically evaluate all results. In experiments where the entire (!lass works on the same mat,erial, the entire mass of the results is statistically evaluated. The students are expected to discard outlying results by the prescribed means. The last technique mentioned (item (4) above) is a self-disciplining of the teacher in the presentation of material. By far the best technique to keep "the analytical problem" before the students is to sprinkle Volume 44, Number 9, September 1967
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the lectures with real analytical case histories which illustrate the theory and descriptive material being presented. The student then always associates the material with reality, and the picture created in his mind is automut~callythree dimensional. A t the Graduate Level
Analytical thinking must be exercised a t the graduate level. At this level, the student should already be familiar with the theory and techniques, and he can bc given greater freedom in approaching problems. At the University of Massachusetts, a course called "hpplied Analytical Chemistry" has been instituted. This course practices the exercise of analytical thinking to the ultimate degree possible. The student is presented with a real problem. These problems are selected from research current in the University and require more than just a routine analysis. These problems originate not only from research programs of the Chemistry Department but can also originate from Chemical Engineering, Agriculture, Natural Resources, Geology, Food Technology, Metallurgy, Biochemistry, or other areas closely allied to chemistry. These areas are often faced with situations which require more than routine analysis. The student taking the Applied Analytical Chemistry course, having been assigned the problem, must contact the man requiring the analytical help. After he has assessed the situation, the student must then select which of the existing analytical measuring approaches are best. suited to his problem. He then proceeds experimentally, forming his conclusions as he goes along. All the while, he must keep in contact with the man who requires the analysis. This insures that the analytical chemist has all the available background and also insures that his answer will best suit the purpose intended. Each student periodically reviews his work before his class, giving reasons for his direction and tentative conclusions from his results; the listening students participate freely. This approach not only exercises the analytical thinking dimension but also unifies the field of analytical chemistq for the student. He no longer views the field as a series of isolated techniques but as a field of interrelated chemical and instrumental techniques, used in combinations for the achievement of the most con-
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clusive answers to problems in the shortest possible time. This approach not only serves to unify the field for the student but actually serves as an "internship" before he proceeds into practice after graduation. Some of the types of problems issued to students are as follows: Certain inorganic residues from organic mzterials were isolated in the Agriculture Department. There was a need to know their qualitative and quantitdve composition. Certain orgsnometallics were being synthesized in the Chemistry Department. Analyses obtained from commercial sources were open to question and had to be verified by several different approaches.
.4n organic pigment isolated in the Food Science Department had to be identified. A process being studied by Chemical Engineering required automatic analysis in situ to monitor changes. The pesticide content of certain crops and waters were required as an adjunct to the work of the Natural Resources Department.
The problems are selected so that answers seem possible. One can rarely he certain since the complexity of a problem is not revealed until one gets into it. However, obviously difficult problems are not used. The practice described above has aroused considerable interest both among students and also among people who have problems with which they would like help. The students of analysis like the challenge and the "Sherlock Holmes" attitude that the work entails. The people with the problems usually appreciate the help they get. Even though this help is only semiskilled, it is free and can be used or discarded as deemed fit. In summary, chemical analysis is an applied science. The teaching of the field must imbue the applied aspects in the student, and this can best be done by using real situations. The student thus trained best fits the demands of the scientific community in which he will find himself after graduation. In the scientific community, there is always a need to know something about the composition and structure of materials, and hence a "three dimensional" analytical chemist is in great demand. He not only finds his work challenging, satisfying, and financially rewarding, but also rewarding because of the recognition he receives through his ability to solve problems.
