College Visitation Program For High School Chemistry Students and Teachers 1.R. Williams and D. L. Powell The College of Wooster, Wooster, OH 44691 Most of the dramatic developments that have occurred in modern analytical instrumentation in the last decade have bypassed high school teachers and students. Meter readouts have disappeared and have been replaced by digital displays. Many instruments are now computer controlled. In order to give high school students and teachers a "real" sense of what is happening in the world of chemistry, it is important to allow them to become aware of these developments in instrumentation. Since 1979, high school teachers from urhan and rural areas of northeastern Ohio have brought their students to visit the College of Wooster Chemistry Department to learn about instruments. The program was initiated by a grant from the Martha Holden Jennings Foundation. The project has also been conducted in recent years a t Towson (Maryland) State College with a slightly different format and in a much modified way in the College of Wooster's annual Summer Science Workshop for high school students interested in science. Before each visit, the high school teacher distributes information about the various instruments to he demonstrated. These handouts give the teacher and students a simplified idea of how the instruments function. After a 15-min introduction to the 4-h session, a problem is posed for the group. Our favorite problem is to have the students ascertain whether "liquid paper" thinner is poisonous. The students are told that their 2-year-old brother or sister has swallowed this material and thev are to trv. to gain as much information as possible concerning this commercial product. Analvsis time and accuracv are clearly. important in . solving this problem. Over the c o k e of the program, we have chosen to give the students such a problem to solve instead of conducting a simple "show and tell" of the instruments because this approach is markedly more intriguing to them. The total group is usually limited to about 20 students. The visitors are broken into groups of three or four, with each group receiving a 25-min demonstration of each instrument. College juniors and seniors are posted a t each instrument as instructors who provide detailed information huilding on the material in the initial handouts. From the infrared spectrum, the absence of various functional groups such as carbonyl, nitrile, and hydroxyl can he noted, as well as the presence of aliphatic hydrogens and a methyl group. Assuming that sodium chloride windows are used in obtaining the infrared spectrum, little information about the heavier atoms present in the unknown is ohtained. However, the Raman spectrum shows plainly the presence of heavy atoms, and the assumption that these might be chlorine or bromine is rather obvious. We usually do not obtain the ultravioletlvisihle spectrum for this particular unknown. Absence of hands, though, would show rather clearly that there are no conjugated systems present in the unknown. In recent years, both proton and carbon nuclear magnetic reso-
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Journal of Chemical Education
nance spectra have been ohtained for the sample. The proton spectrum shows plainly the presence of only one type of hydrogen; the carbon spectrum shows two nonequivalent carbons. Although our simple student mass spectrometer shows no parent peak for the compound, the fragmentation pattern indicates the presence of more than one chlorine. The eas chromatoeranh - . with mass svectral detector provides the mass spectrum of the major component. Because the GCIMS spectrum of the major component gives an unequivocal identification of the sample, it is wise not to use lihrarv search techniques available if one wishes to have the students think ahoutintegrating all of the data which they have ohtained. For the same reason, search routines available with a Fourier transform infrared spectrometer should he avoided. Of the nonspectral techniques, the gas chromatograph shows that we are dealing with a relatively pure material. The differential scanning calorimeter, while fascinating to the students, yields only the negative information that no phase change occurs in the sample between -50 "C and 50 ' C . Since it is not easy to obtain the boiling point using this calorimetric technique, no further information is ohtained from the DSC. A 15- to 20-min period is allocated a t the end for the interpretation and summation of the data. The hieh school students often want to know, in addition to the &alytical application of the data, how the instruments work and how to interpret physically what they have seen. We have found the following henefitsfrom the experience:
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Teachers and students become enthusiastic about their exposure to new instruments. Both groups have been impressed with the fact that underpraduates are able to operate sophisticated instruments. It becomes clear to the participants that, when solving a given chemical problem, avarietv of instruments can be used and the informatibnobtained from-thedifferentinstruments is complementary. High school teachers have become so excited by this program that they have brought groups to Wooster three or four times. Teachers frequently report that students begin to relate some concepts illustrated in their high school courses to things they have seen a t the College of Wooster. The vroeram clealv broadens hieh school students' views of Eheiniitry and &hieves the ha Holden Jennings Foundation's ma1 . of hrideint! - - the aaD - . between high srhools and colleges. Acknowledgment The authors wish to thank the Martha Holden Jennings Foundation for its support of this program and Louise Hellwig for her suggestions after running the program a t Towson State College.
