QUANTITATIVE WORK IN FRESHMAN CHEMISTRY1 HENRY GABRIEL Siena College, Loudonville, New York
IN
THE summer of 1954, the American Chemical Society workshop a t North Carolina State College was held in Raleigh, North Carolina. One of the aims of the general chemistry course, which was common to both the high-school and the college curriculum, was to foster and develop scientific thought and attitude, and the development of proper concepts of chemical facts and principles. Furthermore, the development of an appreciation of the importance of science in social and economic changes was considered es~ential.~ One method of accomplishing these aims is to bring to the student an awareness of the development of science from a disorganized mass of methods to a finely integrated collection of thought processes. One of the major purposes in this development is the realization that science is not truly science unless i t is exact, or perhaps better, precise. The predictability of the behavior of matter and energy under experimental conditions and the development of new ideas and new methods of measurements based on well-organized experimentation and research are achievements possible only through science as opposed to a priori trial and error methods. This concept is clear enough to those who are trained in the various branches of physical science, but the problem is: How can this idea be presented in a palatable fashion t o the young student having his first contact with a formal course in one of the sciences? The popularization of scientific achievement by means of popular books, films, and other familiar devices often leaves the student with only a dim appreciation of the tremendous mental effort and physical labor involved in making these achievements possible. At times students have the idea that the scientist is some kind of a to magician, and the young student is
make the necessary effort to prepare himself properly for a scientific career. I n order to demonstrate to the student the need for precise measurement, keen o b s e ~ a t i o nand , mathematical formulation, a quantitative approach to work in the laboratory is essential. Problem work is always associated mith lecture and class recitation work, but in this connection it is often a chore which the student undertakes for the sake of a grade and in which its purpose is lost. I n the laboratory, on the other hand, collecting data, interpreting them, and finally drawing the necessary conclusion go hand in hand with problem solvingand illustrate thegrowth of scientificideas. I n recent years increasing emphasis has been placed on quantitative experiments in general chemistry courses. A survey of recently published laboratory manuals for first-year college chemistry revealed the distribution of quantitative experiments shown in Table 1. It is noteworthy that about one-third of the experiments in any manual contain some measurement and reading of data. However, far too few experiments with unknowns are used and only two of the manuals surveyed made any attempt toexplainsignificant figures to the prospective experimenter. Too many laboratory experiments are still in the "cook bookl'experiment stage and there is aninsufficient number of experiments which really test the student's power of observation and thinking. It was also brought out last year that high-school laboratory work, if given a t all, is sadly lacking in scientific interest. To illustrate my point, let me imagine a typical cook book experiment, which, I am happy to say, is reluctantly but steadily vanishing from our laboratory manuals. place spproximately gram ot sulfur (yellow, powdered ma, terial, formula S) and one gram of dark-gray iron filings on a filter paper, provided by the instructor. Draw a magnet over the mixture and attempt to separate the two substances. Can you separate the components of the mixture? What is a mixture? Recombine the iron and sulfur or make up a. fresh mixture and
Presented a t the 17th Summer Conference of the NEACT, Tufts University, Medford, Massaehusetk, August 18, 1955. MCDEAEMAN,ELLA B.,"Report on a workshop on the interrelation of high school and colle~echemistry," General Chemistry Workshop of the American Chemical Society held a t North Carolina State College, Raleigh, North Carolina, 1954. 42
VOLUME 33, NO. 1, JANUARY 1956 place it in a. six-inch Pyrex test tube. Light the Bunsen burner and heat the mixture vigorously, until i t begins to glow. Remove the test tube from the flame snd observe that it continues to glow. Allow the tube t o coal. Then beak the tube and notice the grey-black, nonmetdlio, nonmagnetic material. Did a chemical reaction take place? What evidence do you have that s chemical reaction took
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\\'rltr nn rquutiuu fur tlw rewflon Take .I I I I I I P of rhe lrlwk ic.rnw sulfide (FcS) n r d d n y it into n trrt r d l r one-thlnl full oi
