VOL.6, No. 11
QUALITATIVE
ANALYSIS IN SECONDARY SCHOOLS
1955
DISCUSSION ~ A N B. K WADE, SHORTRIDGE HIGHSCHOOL, INDIANAPOLIS. INDUNA
Recognizing that second-year high-school courses in chemistry must and should be given in very few schools, we advocate very elementary quantitative analysis as an excellent type of material for use in the third semester of chemistry. The chief use of it lies in the opportunity that it affords for application and review of some of the fundamentals of general chemistry. At Shortridge High School it has also given a moderate number of pupils a chance to prepare for actual work in industrial laboratories as assistants. A canvass of the chemists who employ these pupils resulted in the quite uniform suggestion that the pupils be taught the following general things rather than be prepared for particular positions: 1-Honesty in regard to figures and values obtained in their laboratory work. 2-Facility in the use of the analytical balance, graduated glassware, etc. 3-How to wash bottles, apparatus, etc. 4-The nature of standard and normal solutions. 5-How to conduct a titration, the use of indicators, end-point, etc. 6-How to carry on a chemical calculation from the data of a titration, etc. At Shortridge the Course 3, as i t is called, is offered only every other semester, and to a selected group of some 10 or 12 chosen from the nearly four hundred pupils of the department. The outline of this course follows: CHEMISTRY 111 This course organized to develop 1. Familiarity with (a) Quantitative apparatus ( b ) Use and care of chemical balance and calibrated glassware
(c) Laboratory cleanliness (d) Neatness (e) Honesty toward results
The supposition is that students of more than average ability, acquiring the above ideas while working quantitative experiments, will be well equipped for usefulness in any technical laboratory. I Reuiew1. Atoms, molecules, reactions and solution of problems-mold 2. Symbols, formulas, equations volume 3. Gram-atomic weights, moles 4. Ionization-reactions in solutions--electrons I1 Apparatus in8olved-
1. 2. 3. 4.
Accurate chemical balances Specific gravity bottles Crucibles Desiccators
5. Burets 6. Pipets 7. Graduated flasks
111 Method1. Intensive review of Chemistry I and I1 (see I) covering about three weeks 2. Acquaintance with and use of apparatus developed as met in the sequence of the work. Theory involved accompanies. IV Sequence-(a) Grauimetric1. Practice weighing of objects-to 4th place 2. Specific gravity determinations 3. Oxidation of magnesium and determination of gain in weight. V Sequence-(b) Volumetlic4. Saturation mcthodsacidimetry and alkalimetry (a) Exemplification-preparation of N HCL--c.P. Na*COs as basis. Introduces standard solutions, normal solutions, indicators, end-point and titration ( b ) Practical analyses of basic substances-examples-lye-washing soda Preparation of standard solution of NaOH against N HCI (c) (d) Practical analyses of acid substances-enamples-dilute shelf acids, vinegar, fruit juices, etc. 5. Oxidation processes (a) ExemplificationBichromate process for the determination of iron (I) . . (11) Permanganate process far the determination of iron (111) Iodimetry-titration of iodine against sodium thiosulfate (IV) Chlorimetry-determination of available chlorine in bleaching powder 6. Precipitation methods Exemplification-determination of silver in coin. (a) VI StoickiometryInterspersed throughout the course.
