CARBON COMPOUNDS IN GENERAL CHEMISTRY* A E T J.~CLARK, MICHIGAN STATECOLLEGE, EASTLANSING, MICHIGAN
A comparison of the teaching of general chemistry and general physics zs presented. A program for the course in general chemistry is suggested, dieriding the work of the course into three approximutely equal parts: (1)non-metallic elements, (2) metallic elements, (3) carbon compounds. This program is then discussed.
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Thirty years ago the teaching of "first-year chemistry" or "general chemistry" was fairly uniform and contined itself almost entirely to what we may call "inorganic chemistry." For the student who wished more chemistry this was followed by a year of analytical (qualitative and quantitative), a year of organic, and a year of physical. Quite in contrast to this has been the teaching of physics. Just as chemistry has been divided into inorganic, analytical, organic, and physical, so physics has been divided into mechanics, heat, sound, light, magnetism, and electricity. However, in the teaching of physics the f i s t year has never contined itself to one or two of these subdivisions but has always covered the whole subject. After this fundamental suwey course, the advanced student may emphasize one or more of the subdivisions through more detailed special courses. The student who goes no farther than the first year's work has a suwey of the whole field and it is the opinion of the writer that the student who wishes to specialize in physics has not suffered by this policy. While some institutions still carry on as of fhirty years ago, many teachers of chemistry have gradually modified the first-year course to include qualitative analysis, and more or less emphasis has been placed upon quantitative experiments and the introduction of physicochemical fundamentals. Only in a few instances, however, have the carbon compounds been treated in any way proportional to the importance of this very large group of substances. None of our textbooks of general chemistry presents this material in such a way as to be very enlightening to the fist-year student. Three or four chapters are not sufficient to present adequately the relationships existing among the various series of carbon compounds. I would like to present briefly a few ideas in connection with the problem of more adequate presentation of the compounds of carbon in the course in general chemistry. In the first place, inasmuch as we recognize that analytical chemistry and physical chemistry are equally concerned with inorganic and organic compounds, I would suggest a different subdivision of general chemistry into three divisions: (1) non-metallic elements, (2) metallic elements, (3) carbon componnds. *Presented before the Division of Chemical Education of the A. C. S. at the Buffalo meeting, August 31September 4, 1931. 99
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I would also suggest that the year's work be divided approximately equally among the three groups. Naturally, the question is immediately raised-"If so much time is to be spent with the compounds of carbon, what is to he omitted that is now being given?" In order to discuss this more intelligently let us present a brief outline of the work to be covered under each subdivision: NON-METALLIC ELEMENTS Chemical elements Laws, gases Atomic and molecular ideas, volume and weight relationships, valence, formulas, reactions, equations, problems Acids, bases, salts Chemistry of any element presents the following facts aboGt that element: History Occurrence Preparation, properties, and uses 0, H, halogens, etc. Compounds-with Acids or bases-salts of, properties and uses of Elements studied-0, H, halogens, C, N, S, P, Si The Periodic System
WTALLIC
ELEMENTS
Solutionsproperties of, solubilities Ionization Equilibrium-effects upon, by temperature and pressure changes; by catalyst; by formation of precipitates, gaseous producJS, unionized products: by changes iil molecular concentration Common ion effect Hydrolysis Oxidation and reduction Structure of the atom Electrochemical changes General study of the metals as toHistory Occurnee Preparation (metallurgy) Properties and uses Compoundsalloys and salts Colloids CARBON COMPOUNDS
Should allow student t o become familiar with the general properties and relationships of such series of compounds as the: HydrocarbonsSaturated IJnsaturated Aromatic Alcoholsmono, di, polyhydric Ethers Aldehydes and ketones
Val. 9, No. 1
CARBON COMPOUNDS
Acids
Esters, fats Carbohydrates Nitrogenous compoundsamines, cyanides, etc. Proteins Aromatic compoundshalogen, nitro, hydroxy, amino, etc.
It will be noted that under the first heading not all the non-metallic elements are discussed. Only a sufficient number are used to develop the fundamental laws and concepts as indicated. Once the student has mastered these and realizes that the chemistry of any element is covered by certain facts concerning the history, occurrence, etc., of the element he is in position to go intelligently t o a reference work and obtain those facts if he desires them a t any time. I do not believe it i s necessary or advisable to present all this factual material in the first-year course. Likewise, in the study of the metallic elements, it is manifestly impossible in approximately twelve weeks t o devote time to each metal individually. There is time, however, t o take up in general the history, occurrence, metallurgy, properties, uses, alloys, and compounds of the metals. A few may be covered in some detail as examples. Modifications in metallurgical practice and detailed variations in properties among the many metals, however, are not essentials in the course in general chemistry in my opinion. Our textbooks could easily be reduced one-third in size by omitting much of this factual, encyclopedic material. This would then make it possible to present the important relationships among the groups of carbon compounds in a systematic manner without unduly enlarging the text. The laboratory work should be appropriate for each division of work. In connection with the first portion of the work the writer advocates fewer test-tube experiments and more experiments of a quantitative nature. Qualitative analysis fits in well with the study of solutions and the chemistry of the metals, but i t must be a brief course with the aim of using it to illustrate fundamental ideas rather than to make expert analysts of the students. From this angle there is little value in a large number of unknowns. I n connection with carbon compounds a number of the simpler preparations and purifications brings the student into touch with the general properties of these compounds and gives him a knowledge of such general operations as distillations, fractional distillations, extractions, boiling-point determinations, etc. I believe that any course in chemistry should be a study of chemistry and not a study about chemistry. The course should teach the student to reason and think in a scientific manner. Interesting practical applications may be presented from time to time with value, but I am of the opinion they should be considered as incidental to the main objective of the course.
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The course should provide a solid foundation upon which the teachers of analytical, inorganic, organic, physical, and the applied phases of the subject may build their courses. Our national society is interested in disseminating a knowledge of chemistry as broadly as possible among our citizens. A large percentage of the students who take chemistry in our colleges take one year only of this subject. The teachers of chemistry can surely advance the aim of the society by making the year of "general chemistry" truly a "general" course, including a more adequate presentation of the chemistry of the carbon compounds.
