PACIFIC SOUTHWEST ASSOCIATION OF CHEMISTRY TEACHERS TEACHING ANALYTICAL CHEMISTRY' LOUIS LYKKEN Shell Development Company, Emeryville, California
ITIS generally agreed that analytical chemistry courses are an important feature of college curricula for the training of chemists and chemical engineers. However, there is not complete agreement in the role and scope of such courses because of the unpredictable placement of chemically trained college graduates. This dilemma poses a problem but it appears resolvable by compromising the needs of graduate work, industry, and teaching, the three important fields which absorb the chemically trained graduate. Actually, these three fields need about the same emphasis on basic analytical training and there is little conflict in the desired analytical coursework except in the special case where the student is being prepared for industrial analysis. Since the latter case requires only augmentation of the basic groundwork, this paper deals only with the teaching of undergraduate analytical chemistry in general. FIRST-YEAR COURSE
SEQUENCE OF COURSES
After the firsbyear chemistry course, the sequence of the basic courses in chemistry and physics is an important consideration. It is desirable to coordinate the analytical chemistry course with these related courses in order to allow a logical progression of learning, to avoid repetition of theoretical expositions, and to give an opportunity for stressing various aspects of analytical chemistry. These considerations suggest the following sequence of important chemistry courses: (1) give the conventional quantitative (inorganic) instruction in t.he second year along with advanced qualitative analysis and/or organic chemistry; (2) teach physical chemistry and organic chemistry in the third year if the latter has not been given before; (3) offer a full year course of technical analysis in which rigid or elaborate oroof of laws and conceots should be minimized and the stress should be on variety of work rather than specialization in a few fields. I t is desirable to place equal emphasis on class and laboratory work and togive one-third of a year each to qualitative organic and quantitative analysis and to modern concepts and tools of analysis. The basis of electrometric, spectrophotometric, and other physical analytical techniques should be taught in the physical chemistry or physics courses. A full-year course in physics is an important adjunct to the second-year chemistry courses because progress in modern analytical chemistry involves measurement of physical properties of various kinds and because physics is the basis for the instrumentation of methods. If a choice is necessary, physics is considered of greater value than advanced courses in chemistry, excepting organic chemistry. Training in physics is of considerable value in a general way because it stresses the practical use of mathematics.
The firsbyear preparatory chemistry course should consist of the conventional study of general chemistry with at least one-third of the year devoted to qualitative inorganic analysis and with about equal emphasis on class and laboratory work, especially in the qnalitative portion. If possible, it is desirable t o include some organic chemistry, stressing empirical formulas and prominent reactions. I n order to promote understanding and reasoning the emphasis should be on the basic chemical background and practical problems, including simple analytical calculations, and not on specific details and properties. Putting it another way, the instruction should stress qualitative separe tion of like elements into groups and emphasize the chemistry of the group. A suitable way of accomplishing this is to note similarities and differences between common elements and typical compounds, and to study type reactions rather than commercial processes and materials. Some thread of reasoning should be sup- QUANTITATIVE ANALYSIS Laboratory Work. Normally, there should be two plied which the student can use for connecting the three-hour laboratory periods per week devoted t o chemical facts learned. ' Based an a paper given at the meeting of the Northern Cali- quantitative analysis throughout the second year, but fornia Section of the Association on Ootober 21, 1950, at Mills consideration should he given to providing three such periods in the last third of the work. While optional to College.
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the elementary grmimetpic .work should come first, starting with very simple determinations designed to give the student confidence in his work. The volumetric vork should be given in the middle of the year but only the initial standard solutions should be standardized by the student. Standardized solutions should be provided where the emphasis is on separations, end points, etc. In general, the samples should be homogeneous, easily soluble, and known to the instructor; 8 to 12 samples should be nsed for gravimetric practice and 10 to 15 for volumetric tests. At least one sample should involve several separations (i.e., limestone or brass) and, wherepossible, samples of commercial materials should be utilized. Weights and a buret should be calibrated sometime during the year. All common quantitative techniques should be covered and the last three or four determinations should involve a difficult separation, titration, or analytical step. Time should not be mast,ed in building crude apparatus; instead standard commercial units should be provided. After the first third of the work, rapid balances should be available for regular use. The teaching practice used in the laboratory is important and requires intelligent study. I t is necessary to demonstrate critical points individually at the right time. A few experienced instructors are generally more effective than a number of inexperienced ones because the former can detect the opportune time for the demonstrat,ion and know what difficulties are to be anticipated. All class instructors should spend some time in the laboratory and individual demonstrations should be nsed when possible. Proper format for the record book should be taueht and stress should be nut on the student's ability to translate results properly in making a report. Safety needs should be stressed and emphasized when a possible hazard is encountered. To this end, safety apparatus should be readily available and the students required to use it. Ctassruork. While more time can be used profitably, a suitable compromise is to spend two one-hour classes per week teaching analytical chemical theory, problems, and basic background of the apparatus used in the laboratory work. An important feature of the classwork is to present and explain the unit operations of analytical practice (i.e., filtering, weighing, titrating, calibration, etc.) and to teach the basis for the laboratory experiments. An important responsibility of the instructor is to develop in the student an ability to schematize the knowledge received and to develop his willingness to learn in a serious manner. It is the function of the instructor to inspire his students to learn "why" through thought and interest, thereby achieving a real understanding of the subject by thinking "analytically." I t is desirable to use ample time to present important features, to cover the subject well, and to avoid teaching too much too fast. The basic physical and chemical principles should be taught thoroughly and the student should be trained to state them fully yet concisely. A good way to develop this talent is to give tests regularly, requiring statement-
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type answers. I t is also desirable to give "open-book" final examinations because they are a good test of the students ability to think; in such examinations, it is important to provide a varity of questions or problems and to give ample time for their solution. The classwork should be a combination of lectures, quiz-sessions, and problem-teaching. All possible presentations and considerations should be related to practical usage and, obviously, the instructor should be familiar with illustrative practical applications. The significance of the various chemical and physiccl laws should be stressed but their derivation and justifcation can be left to other basic courses in the curriculum. Considerable emphasis should be placed on precision, accuracy, and significance of analytical figures. Problems are an important feature of analytical chemistry because they aid in developing analytical thinking and serve to broaden the field of interest. I t is important to select a sequence of problems that requires an increasing degree of deductive and inductive reasoning. As in laboratory work, it is desirable to start with very simple problems in order to develop the student's confidence in solving them. In addition, it is necessary to repeat certain types to emphasize the reasoning used. I t is generally preferable to select problems that are based on actual analytical processes and that have answers that fall in a practical range. Thus, problems can be used to teach the student a proper sense of analytical values and to develop thinking along analytical lines. TECHNICAL ANALYSIS
The purpose of the final course in analysis should be to encourage interest in analytical chemistry and to teach an understanding of its possibilities as a service. Such a course should be equally useful to a person eventually doing chemical analysis or using data obtained in analysis. This course should be given in the senior year so that basic principles already learned can be utilized with a minimum of effort; it should include both qualitative and quantitative applications and should consist of two one-hour classes and two three-hour laboratory periods per week. I t is advisable to separate the work in three parts. One-third of a year can be profitably devoted to organic analysis, dividing the coverage between qualitative identification of compounds and quantitative determination of functional groups. Another third of a year can be used for a study of general fields of technical analysis, comprising gas analysis, fuel analysis, microanalysis, metal analysis, etc. It is desirable to select the laboratory work and class work to illustrate (1) new reactions, (2) complexing reagents for performing separations, (3) utility of columns (distillation and chromatographic) as separation tools, (4) sampling techniques, (5) means of sample decomposition, etc. The last third of the year should involve the use of modern instruments for analysis, such as pH meters, titrometers, polarographs, electrolytic apparatus, spec-
JOURNAL OF CHEMICAL EDUCATION
trophotometers, simple colorimeters, emission spectrographs, etc. The presentation and arrangement of the necessary class and laboratory work need careful study and planning. A general treatment is best in order to cover the most ground. The instructor needs to instill in the student an appreciation for new approaches and a familiarity with them. There is little value in intensive study of a narrow field because of the uncertain use of such specialization. It is important for the student to have contact with actual commercial apparatus and practical samples. There is little to he gained from wasting the student's time on building apparatus except the simplest kind. Where apparatus is not readily accessible, it is desirable to discuss the utility of such equipment from photographs and drawings and to visit laboratories where such apparatus can
be inspected and demonstrated. Another important feature of the classwork is to teach the proper use of analytical literature and reference hooks. Thus, the student should be required to look up some of the information needed for class or laboratory work. RESEARCH PROJECTS
Whenever it can be worked into the curriculum, all students in chemistry or chemical engineering should do a research project in the senior year. Such a project should require a t least half of a year and should culminate with the writing of a report or a thesis. This work should teach the proper approach and handling of practical problems of restricted scope, and should not be connected with the regular line of graduate research work being done. The project should require the writing of one or more progress reports.
