Nelson W. Hovey University of Toledo Toledo, Ohio
I
The Present and Future of Qualitative Analysis Report of a Survey
T h e survey upon which this report is based was suggested by Dr. Theodore A. Ashford, Chairman of the Examinations Committee of the Division of Chemical Education a t the March, 1962, working sessions of the Brief Qualitative Analysis Subcommittee. Its purpose was to determine to what extent new concepts in the teaching of chemistry have affected the content and place in the curriculum of courses in qualitative analysis. The information provided has served as a guide in the preparation of a new Brief Qualitative Analysis Examination to he published in 1964 and will aid the Examinations Committee in planning future examinations. Copies of the questionnaire used and additional information may be obtained from the author. The Survey The questionnaire was designed to give a maximum of information with a minimum of effort on the part of the recipient. Despite its 6-page length, estimated average completion time was one-half hour. Responses to the 14 questions were multiple choice requiring a check mark. Comment space was provided. The 500 questionnaires were sent to chemistry departments meeting one or more of the following requirements: accreditation by the ACS, recent use of ACS examinations in Qualitative Analysis, or interest in chemical education evidenced by membership in the Divisionof ChemicalEducation. Geographical location and type of institution were varied for broad coverage. The completed questionnaire was returned or letters of the 500. A of explanation were written by total of 458 (91.6%) of the questionnaires were available for analysis. These 458 questionnaires covered 543 courses involving over 100,000students. Selected Data from the Questionnaires ~h~ factthat approximately 1800 IBM cards were answers is an requked to record the illdicatioll of the wealth of information that is the summary which follows, responses have beell grouped into fairly hroad ranges where ~ractical,and material pertaining specifically to ACS examinations in qualitative analysis has heen omitted, ~h~ sectioll headings are essentially the questions which appeared on the questionnaire and the tables are numbered to
correspond. In general, the interpretation of the data is left to the reader. W h a t i s the place of inorganic qualitative analysis in your program? Comparison of Table 1 with previous survey dataI.2 shows a continuation of the trend toward inclusion of qualitative analysis with general chemistry and elimination of the separate course. An unpublished survey by W. C. Oelke in 1958 covering 133 institutions showed 49% giving qualitative analysis only in the freshman year, 22% giving an advanced course only, and 26% giving both. Table 1.
Place of Qualitative Analysis in Chemistry Program Nnmher
General Separate qua1 Analytical and General and analytical Qual and analytical All three rone T"talnumbergiving Part of general q"das:
252 90 64 24 3 2 7 342 156 45 543
Separate course Part of analytical number of courses covered by survey
Ci.
55.0 19.7 3.5 14.0 5.2 0.7 0.4 1.5 63.0 28.7 8.3
How many students per year enroll in courses including qualitative analysis? The purpose of this question was to permit a check of the distribution of the data with respect to department size and to provide all estimate of the nunlher of students covered by the survey. Since nearly 25y0of the colleges and universities in the Vnited States returned questionnaires and the method of sampling favored larger institutions, the coverage in terms of students in Table 2 is probably 30-40%. How many semester hours are devoted to classroom work in qualitative analysis? Table 3 gives an idea of the relative emphasis on qualitative analysis theory in different courses and at different institutions. In this table and all which follow, qualitative analysis in analytical chemistry is omitted since only 45 of the 543 courses covered by the survey were of this type. How many semester hours are devoted to laboratory work in qualitatiue analysis? Table 4 shows that the J. CHEM.EDUC.,17,220 (1940). J. CHEM.EDUC.,27,675 (1950).
Table 2. Number of Students Taking Qualitative Analysis Courses No. students per year Gen ehem Sep qud Anal chem
Under 50 % NO.
50-99 No. %
100-299 No. %
300-499 Nu. %
Over 500 No. %
Approx. totals
44 85 32
67 33 7
136 32 6
40 3 0
52 3 0
95,OW 14,500 1,500 ii n t nm~
13.0 55.3 71.1
410 / Journal of Chemicol Educofion
19.9 20.8 15.6
40.0 20.1 13.3
11.8 1.9 0.0
15.3 1.9 0.0
~
~
i
Toble 3.
Total Semester Hours Devoted to Classroom Work
No. semetiter class hours
Under 20 % No.
No.
General chem Separate qual
117 20
91 100
65.2 14.0
Table 4. No. semester lab hours
General chem Separate qual
109 49
27.3 63.7
30-59
No.
31.3 31.2
Thioacetamide No. % 65.2 227 101 64.3
average laboratory time for qualitative analysis in general chemistry is approximately two-thirds of the average for separate courses, a considerably larger fraction than for classroom time as shown in Table 3. It should be noted that the ratio for classroom time would be larger if time spent in the lecture course in general chemistry on theory basic to qualitative analysis were to be included. Some may have included this, but probably most did not. What system i s used for the separation and idmtifieatzeatzm of cations? The figures in Table 5 show that thioacetamide is replacing hydrogen sulfide but perhaps not as rapidly as might be expected. There has been some criticism of ACS qualitative analysis examinations on the basis that sulfides are too much emphasized. This appears not to be justified. What cations are identified i n the laboratmy? Table 6 indicates that in qualitative in general chemistry, there is a definite tendency to limit the laboratory work to a select list of cations. In the separate qualitative course, no ion on the Sit was covered by less than 90%. The list for the separate courJe has not changed significantly since Oelke's 1958 survey. As might be predicted, as qualitative analysis is shifted to general Table 6.
18 31
7.5 22.3
Over 60 No. %
%
Average lah hra per aemester
-Separate Cation
qual-
Nonsulfide No. % 12 3.5 7 4.5
Semimicro No. % 89.3 292 96.1 149
Macro No. % 35 10.7 6 3.9
chemistry, ion coverage in this type of course becomes more complete than when a separate course also was offered. Oelke's report shows five cations in the range 44-63%; in this study the lowest coverage rvas 66.3%. What anions are identified i n the laboratory? Table 7 shows that anion analysis continues to be much less popular than cation analysis with only 6 ions covered by more than 90%. As wa? true of the cations, coverage in the qualitative in general courses has increased since the earlier surveys were made. Average coverage of the 22 ions common to both the 1958 and the present surveys increased from 42% iu 1958 to 56% in 1962.' What relative emphasis i s given to the topics listed below? The topics listed in Table 8 were selected after consulting a numher of qualitative analysis texts. Space
The questionnaire provided space for cations and anions identified but not listed. Under "Qualitative Analysis in General Chemistry'' the total number of additional rations and anions was 56. For "Separrtte Qualitative Analysis" the number was 71. In addition to anions derived from different oxidation states of elements in the standard list, cations and anions from a total of 12 additiond elements were inoluded. Of thew?, the ions of Li,Mo, Si, TI, Ti, W, U, and V were most popular.
Table 7. Order of Preference for Anions
Order of Preference for Cations
Qual in general chemistry % Cation
25 35
Average hours per semester
System Used for Separation and Identification of Cations
Hydrogen sulfide No. %
System
Over 40 No. %
%
Total Semester Hours Devoted to Loboratow Work
Under 30 % No.
Toble 5.
20-39
Qua1 in general chemistry
%
Anioo
None c1SO,'-
c0,BrINOss2-
0/,
-Separate Anion
qual-
%
None CI SOP BrINO,-
cosss01~POP
Volume 40, Number 8, August 1963
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41 1
Table 8.
Relative Emphasis Given to Theory Topics
a u a l in general chemistryTook % .Redox equations Solubility product Ionization equilibria Common-ion effect Solution concentration Acid-base theory Amphaterism Hydrolysis equilibria Solution properties Complex ion equilibria Oxidation potential Ionic size and properties Complex ion structure Indicators
----Separate Topic
qual-
70 ..
95
Solubility product
98
89 81 79 77
Complex ion equilibria Red& equatiork Acid-base theory Amohoterism
86 85 83 82
69 57 52 52
Complex~ia
