Classroom demonstrations of ion-exchange resins

ERNEST H. SWIFT. California Institute of ... And at this stage of his development there seems to be no ... begin this survey by developing an analogy,...
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DECEMBER, 1950

A PROPOSAL FOR A REVERSAL OF TRENDS! ERNEST H. SWIFT California Institute of Technology, Pasadena, California

INMY opinion there are certain

values which are potentially inherent in a course in qualitative analysis and which can he uniquely realized by a properly designed course, and they are as follows: First, such a course offers a unique opportunity for the classification, systematization, and correlation of a large and useful background of factual inorganic chemistry. This is true because the basis of qualitativc systems is a process of first making use of the more general properties of the elements for major group separa,tions, and thereafter proceeding to utilize increasingly more specificproperties in order to etyect the separations of subgroups, of ~ingleelements, and, finally, to make the confirmatory identification of single constituents. Unfortunately, the student frequently is swamped with detailed material before this general principle is adrquately emphasized. Second, the laboratory work of a course in qualitative analysis offers a unique opportunity for demonstrating the application of a wide variety of chemical principles to experimental work carried out by thv student himself. And a t this stage of his development there seems to be no substitute for such experimental work as a means for fixing these principles and their application; and it should be emphasized that these principles are applicable not only to qualitative analysis, hut to chemical processes of all kinds. Third, a course in qualitative analysis can he of fun?. tional value in illustrating and providing t.raining in I: wide variety of useful analytical techniques-and again emphasis should be placed on the fact that these techniques are not restricted to analyt,ical processes. As a collateral asset, and one which is frequently uniPresented ns pert oi tho Symposium on Teaching Qualitative Analysis a t the 117th Meeting of t,he American Chemical Society. Philadelphia, April, 1950.

derestimated, a courve in qualitative analysis offers rather unique opportunities for the development in the student of a quality which I shall call intuitive resourcafulness. Fortunately, no textbook of qualitative analysis can provide for all of the unforeseen possibilities which arise in the course of various analyses, especially under student use. Therefore a student is forced to face and solve situations on his own initiative; and although I may not be an ent,irely impartial observer, 1 believe that there is evidence that students who have had a good coarse in qualitative analysis develop this qua1it.y to a greater extent than otherwise. If we assume that these values exist and are capable of realization, we a.re required t,o find an explanation for the fact that the time allotted to courses in qualitative analysis is being rapidly decreased and in some institutions such courses have been completely abandoned. In seeking an explanation for this situation one is tempted to accept the situation as inevitable and to assign the blame to certain specific developments, such as the use of spectrographic methods, which have decreased the functional value of the conventional system of inorganic qualitative analysis. However, even with a full appreciation of these specific developments, these seems possible just,ification for a survey of the status of qualitative, and to a certain extent of analytical chemistry, from a much more general point of view. I shall hegin this survey by developing an analogy, and with full appreciation of the danger of argument by analogy. There seems to he considerable evidence for the validity of the observation, applicable to the development of hoth plant and animal organisms, that when growth stops, regression or degeneration begins. Cessation of growth may be caused by attainment of a hereditasy age limit or failure t,o adjust to changes in environment. This same generalization has been applied to social 01.ganisms, and is observed in Toynhee's treatment of the