Morris F. Stubbs New Mexico Institute of Mining ond Technology Socorro
There is an increasing tendency to include qualitative analysis in the general chemistry program. We believe this trend is in the right direction provided qualitative analysis is integrated in the course as a means of teaching the principles of ionic equilibrium and of developing considerable initiative and resourcefulness in the laboratory. Our experience has shown that the practice of having students work out their own analytical procedures is a highly successful one, not only for teaching the properties of the ions and the principles involved in the analytical separations, but also for keeping the laboratory work from becoming mere routine. Furthermore, student interest is maintained at an unusually high level. Our students develop semi-macro tests for eight common anions, together with procedures to be followed when testing in the presence of possible interfering ions. The semi-macro schemes for the analysis of the usual uumber of cations are worked out after completion of tests which enable the student to fill in a flow sheet for the precipitation, separation, and identification of the cations in the various groups. We believe teachers generally will agree that the procedure described has many pedagogic advantages. Some instructors, however, may fear that the average
Qualitative Analysis in the General Chemistry Program
freshman is not capable of working out his own scheme of analysis without considerable individual attention and without requiring more time than is usually available. Others may feel that the analytical results will not compare favorably with those obtained by students using conventional directions. We have recently completed a study of the analytical results obtained by 256 "run-of-the-mill" students who worked out their own analytical procedures. The percentages of ions reported both correctly and incorrectly by our students were generally as good or better than those reported by several authors in THIS JOURN.~L for analyses made by students using conventional methods. Ihthermore, the laboratory time required has been found to be approximately the same as that used by students who perform an equivalent number of the preliminary experiments given in many manuals prior to the directions for the analytical procedures. One instructor has been in charge of each section of approximately 24 students. We are convinced that the program described is valuable in helping to keep the freshman laboratory work from becoming lLcook-book" chemistry, and for giving more than the usual amount of training in learning to think independently and critically.
Volume 36, Number 8, August 1959
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387
