0
QUALITATIVE ANALYSIS I N COLLEGE CHEMISTRY' A Committee Report2
SOME years ago, a survey \vas made of the aims of TABLE 1 qualitative a n a l y ~ i s . ~Based on the data furnished by The Place of QualitativeAnalysis in College Chemistry this survey, a series of objective tests4 measuring Curricila achievement in theory and facts of qualitative analysis T y p e of courseswas prepared. Ntanber Part of Total I n the postwar period a number of reorganizations of 4 f yeOne se- One ga. courses plies mester Yea? chem. reported chemistry curricula have been made. In order to con- - Area stmct new test forms it became necessary to discover S e w England 20 16 3 10 29 what happened to Qualitative Analysis in this shuffle. New York and Middle Atlantic Therefore a questionnaire was prepared to determine in States 49 39 6 28 73 Middle West and the postwar curricula: 7 -
1. The place of qualitative analysis in college chemistry curricula. 2. The aims of qualitative analysis. 3. The subject matter covered. These questionnaires were sent to colleges in all parts of the country. From returned questionnaires the following data were obtained. The Place of Qualitative Analysis in College Chemistry Cum'cula. The results appear in Table 1. Those colleges which indicated qualitative analysis t o be offered for a quarter as a separate course were included in the data for the one semester group. These data indicate that about seventy per cent of the colleges offer a one semester course, while about half the colleges include a course as a part of general chemistry. In many cases this is the only course offered in qualitative analysis. About twenty per cent of the colleges were doing it both ways for different purposes. Relatively few colleges have a year course. The midwestern colleges seem to prefer a single course in their curricula, while in the eastern area about half the colleges offer two or more courses. I n the previous survey only thirty-five per cent of the colleges included qualitative analysis in the second term of general chemistry. This indicates a growing tendency to include qualitative analysis in general chemistry. Presented as part of the Sympasium on Teaching Qualit* tive Analysis at the 117th Meeting of the American Chemiertl Society, Philsdelphih April, 1950. ' A subcommittee of the Committee an Examinations and Tests (of the Division of Chemical Education of the American Chemical Smiety), composed of the following members: E. K. Bacon, Union College; Fred H. Heath, University of Florida; C. S. Martin, Bowling Green State University; Rufus D. Reed, State Teachers College s t Montclair; H. W. Rogers, Colgste University; Bmce V. Weidner, Miami University. AND A. CIWDIUL,J. CHEM. REED,R. D., W. P. CORTELYOU, EDUC.,17,220 (1940). ' Cooperative Tests Project, Educational Testing Service, 15 Amsterdam Avenue, New York City.
Northern States South West and Southern States Rocky Mountain and Pacific Comt States Total
62
36
2
26
64
15
11
1
6
18
14
10
1
10
21
160
112
13
80
205
The A i m s of Qualitative Analysis. The collaborators were requested to indicate the per cent of a mark which they would allot t o each of the eleven aims investigated. I n this survey, as in the previous one, accuracy in analysis was the most important factor of the mark. Ability to write equations for the reactions was ranked second by the general chemistry group and one-semester group, but fourth by the one-year group. It was ranked second in the previous survey. Solving problems was considered more important in the separate course groups than by the general chemistry group. It was given second rank by the year group, third by the one-semester group, and fifth rank by the general chemistry group. In the previous survey it was given a composite rank of fifth. Ability to think logically was placed fourth by both one-semester and general chemistry groups and sixth by the one-year group. In the previous survey it was given eighth place. This might indicate thatthe idea of mental discipline is gaining ground. Skill in laboratory manipulation is given fourth place by the general chemistry group, while i t is given seventh place by the other groups. Accuracy, completeness, and neatness in recording data were given last place in the previous survey but placed eighth in all three groups of this survey. Ability to quote known facts regarding properties of substances involved in the analysis was given third place in the previous survey but in the present one was given fifth place by the general chemistry group, sixth by the one-semester group and tenth by the one-year group. Ability to specify short-cut methods in analysis is considered more important in the one-year rourne.
JOURNAL OF CHEMICAL EDUCATION
616
Ability to specify laws and theories concerned in reactions or analytical steps and the ability to translate the description of an unfamiliar analysis into terms of what an analyst found to be present or absent were given low ranks in both the surveys. Content of Laboratorl/ Work. The questionnaires indicate that the following cations are considered of primary importance in all courses: aluminum, ammonium, barium, cadmium, calcium, chromium, cobalt.! copper, lead, mercurous, mercuric, nickel, potassium, silver, 80dium, and zinc. Where the course is part of general chemistry there is some tendency to omit hismut,h, magnesium, manganese, and strontium. There is a, stronger tendency to omit. arsenic, antimony, and t,in. All of tho above werr gcncrallv includcd in the separatrcourse. Less than five per cent would inclnde in the s e w a t e course such ions as gold, molybdenum, platinum, and t.ungsten. Lithium held a minor posit,ion in hoth typrs of courses. The agreement for t,he anions was spotly, with only bromide, carbonate, chloride, iodide, sulfate, and sulfide considered of primary importance in hoth types of courses. These were followed closely by phosphate and snlfite. I t is assumed that nitrate should be included in this first group hut through error was omitabedfrom the questionnaire. Half of those reporting for separate courses would include acetate, arsenite, arsenate, borate, chlorate, chromate, ferricyanide, ferrocyanide, fluoride, oxalate, thiocyanate, and thiosulfate. For the other course the chance for these ions being included varied from thirtyseven to eight per cent.
Ca2culation.s. The following table gives t,he distribution of the types of problems given in the course and considered to be of sufficient import,anceto be included in the general testing program. TABLE 2 Types of Calculations Considered Important in
Qualitative Analvsis
T y p e of ealcdation, Prep:~ringmolar and normal solutions Mass action Ioniastion constants p11 values Solubility product Ilcgree of hydrolysis Complex ions Oxidation-reductionand e. m. f .
Approzimate per cent o f answers approving in-elusion-Part q f general Separale chemistry mum 67 72 69 66 75 30 26 29
87 89 89 78 89 75 75 57
Theory and Other Subject Matter. A study of the questionnaires received indicated that over sixty per cent of tho collaborators considered knowledge of the following necessary for a course in qualitative analysis. Their relative importance is in the order given:
1. Laboratory procedure for the analysis of simple unknown groups. 2. Analysis of unknowns com~osedof cations from two or more groups. 3. Control of ionization of H2S and NHdOH and utilization in group analysis. 4. Theories of ionization of electrolytes. 5. Heterogeneous equilibria and solubility product. 6. Theory of ionisation of wat,er and hydrolysis. 7. Theory of oxida.tion-reduction. 8. Simple eqwations and oxidat,ion-reductionequat,ions. 9. Amphoteric substances. 10. Theory applied t,o eqnilibria of weak rlect,rolytes. Over sixty per cent of the separate course groups but less than forty per cent of the general chemistry group rated the following a?necessary: 11. Ruffersolutions. 12. Theory and utilization of complex ions. Less than fifty per rent of all collaborator- considered as necessary : 13. 14. 15. 16.
Procedures involving insoluble solid unknowns. The theory of indicators and pH. Br6nsted theory of ionization of acids and bases. Calculations involving amphoteric theory.
Less than twenty-five per cent of all groups would consider as necessary the following:
17. Analysis of cation nnknowns containing phosphates. 18. Colloidal phenomena and adsorption. 19. Werner coordination theory.
Conclu.9ions. From a stndy of the data obtained in this survey, one may conclude that: (1) Qualitative analysis is usually taught as a onesemester course. Ahout fift,y per cent of the colleges include the subject in the second semester of the course in general chemistry. There is a growing tendency to consider qualitative analysis as part of general chemistry. About twenty per cent of the colleges offer more than one course of qualitative analysis in their curricula. (2) There is little variation in the cations considered in any type of course. There is considerably more variation in the nnmber of anions. Where qualitative analysis is taught as a part of general chemistry only the most common anions are considered. (3) For qualitative analysis as part of general chemistry, calculations involving: (1) degree of hydrolysis; (2) complex ions; (3) oxidation-reduction, are usually omitted. They are included in the separate courses. The emphasis on calculations is greatest in the year courses. (4) The separate courses include much more theory. Where qualitative analysis is part of general chemistry, buffer solutions and theory and utilization of complex
677
DECEMBER, 1950
ions are not stressed. In a11 courses, there is a tendency to omit insoluble solid unlmowns, theory of indicat,ors and pH, Br6nsted theory, calculations involving amphoteric theory, analysis of cation solutions containing phosphate, colloidal phenomena, and the Werner theory. ( 5 ) There has been no significant change in the aims of qualitative analysis in the past ten years In the
year course, t,here is more emphasis on the calculations and the theoretical subject matter. ACKNOWLEDGMENT
The Committee wishes to acknowledge the assistance of Irvin Gawley of Tenafly High School in tahulating thedataforthisreport.
