Promoting the Discipline of Chemistry A Vacation Chemistry Program for High School Students Ronald L. Blankespoor and Kenneth Piers Calvin College, Grand Rapids, MI 49546 There has been much concern expressed recently, both in this J3urnal and elsewhere, aboutour ability (or inability) to attract capable high school students to careers in chemistry. I t seem; clear that each of us will have to make special efforts to address this problem if we hope t o see a reversal in current trends. In this paper we wish to describe a simple, but effective, two-day, activity-based chemistry program directed to high school juniors and seniors. We have operated this program biannually since 1985 and offer it on our camous between Christmas and New Year's Dav. Between 35 and 50 students have attended each of the programs, drawn from about 15 to 20 hirh schools in the West Michiaan area. we hope to: (1) increase the By means of this participants' understanding of and appreciation for the field of chemistry; (2) introduce the students t o laboratory techniques used in the synthesis and analysis of compounds; (3) demonstrate to the students state-of-the-art instrumentation used in the analysis and identification of compounds; and (4) improve the laboratory skills of the students. In what follows, we show in detail how we have structured the program in order t o achieve these objectives. Afew comments on the organization of the program might be of interest. In earlv November letters are sent to high school chemistry teachers within about a 50-mi radiusof the Colleee askinr them to inform students of the pronram and to distribute application forms to those who &e interested. In early December we select up to 50 students who have applied for the program and invite them to attend. We have found that nearly all those invited do, in fact, attend the program. We ask the students to bring along a hag lunch. We provide a beverage for each day, safety glasses for the lahoratory, name tag, and, of course, laboratory outlines and materials. Drogram Outline Day One: Synthesis of Aspirin and Qualitative Analysis of Analgesics After a short classroom introduction to the program, the students proceed to the laboratory. They are informed of rules and procedures pertaining to laboratory safety. The experiment for the morning, whichis the synthesis of aspirin via acid-catalyzed acetylation of salicylic acid, is discussed in detail before the students, working in pairs, carry out the experiment. Among the techniques introduced in this experiment are use of a balance, crystallization, vacuum filtration, and melting point measurement. After the students have isolated the product, i t is left to dry until the afternoon session. With the time remaining in the morning session (usually about 45 min), the students are taken on a tour of our instrument room where they are given very hrief introductions to, and demonstrations of FT-NMR, FT-IR, and a computer-driven HPLC system. After the lunch break students return t o the laboratory and characterize their aspirin product. The synthetic aspirin is tested for the presence of unreacted salicylic acid hy means of the ferric chloride test for phenolic hydroxyl 548
Journal of Chemical Education
groups. Percent yields are calculated, and the melting point of aspirin (which occurs with decomposition) and that of salicylic acid is measured. While the students are completing these tasks, the instructors obtain C-13 NMR sDectra of both salicylic acid and aspirin. An FT-IR spectrum&ing the diffuse reflectance sampline . - accessorv is also obtained from each of these materials. The aspirin svnthesis experiment is ended with a short discussion of the various spectra obtained. Most students areable tounderstand that C-13 NMR orovides information about the number of different carbon aioms in the structure of a compound. Thus the spectrum of salicylic acid has seven singlets in the proton decoupled C-13 NMR spectrum, whereas aspirin displays nine such signals. Similarly most students understand that the infrared spectrum of salicylic acid displays only one absorption due to a carbonylgroups a t about 1670 cm-', whereas aspirin displays two such ahsorption bands a t about 1750and 1695cm-I. Clearly the synthesis has served to introduce a second carhonyl group into the molecule. In this way we hope that the students gain an appreciation for the power of modern instrumentation in structure elucidation. The remainder of the afternoon is devoted to thin-laver chromatography (T1.C). After a short introduction to ihe principles and terminology of TI.C, the students proceed to analyze a variety of commercial analgesics for the presence of acetaminophen, aspirin, caffeine, phenacetin, and salicylamide. This is done by first running a TLC plate of the five reference compounds and then a plate spotted with several analgesic preparations. The spots are visualized first under a UV lamp, then by iodine staining. By comparing the Rt values of the s ~ o t on s the analnesic - olate . with the Ri values obtained for t6e five reference compounds, the studdnts are able to make tentative conclusions about the composition of the analgesics. Some of the studeuts comment on the similarity of TLC to paper chromatography, which they have done in their high school laboratories. Day Two: Careers in Chemistryand the Quantitative Analysis of Cmmercial Aspirin The first 40 to 50 min of the second day of the program is conducted in a classroom and centers on a discussion of the topic "Careers in Chemistry." The question of how one becomes a chemist is addressed and a typical ACS-approved BS degree program in chemistry is outlined. We emphasize that undergraduate students are strongly encouraged to become involved in a research project with a faculty member. Then data from a recent employment outlook taken from Chemical and Engineering News' is presented. Job opportunities for bachelor-level chemists are summarized and advanced degree programs presented. Often studeuts are interested in what distinguishes the work done by a PhD chemist from that of a chemist with a less advanced demee. Students are encouraged to think of chemistry as a " h i , challenging, and exciting discipline and are asked to give serious thought
' Hilernan, 6. Chem. Eng. News 1989, (Oct. 23).22
toa major in chemistry when they enter college. Finally, they are invited to browse through a copy of Opportunities in Chemistry Today ond Tomorrow', which we have available in the laboratory. Following this presentation, students enter the laboratory for the remainder of the day. The experiment involves the quantitative determination of the percent by mass of aspirin in a commercialtablet. This is done by titration of a weighed, ground-up tablet dissolved in methanol-water with a standardized sodium hydroxide solution. Working individually, each student must prepare a sodium hydroxide solution by dilution of a stock solution, standardize it using potassium hydrogen phthalate as a primary standard, and then use the standardized solution in the analysis of the aspirin tablet. Students are told to repeat titrations until they are satisfied that the r e s u h are con&tent. This experiment requires 3 to 4 for most students. The results of the student titrations are evaluated by the instructors for accuracy and precision. The 10 best results are selected and these students receive a letter of congratulations and a small cash prize.
Evaluatlon While we have made no systematic effort to evaluate the success of this program, anecdotal information (from the students and some of their teachers) suggests that the students enjoy the experience and benefit from it. We believe that the program, in a modest way, accomplishes its goals, with minimal expense. While the program certainly could be offered without cash prizes, the competitive nature of the second day's activities is enjoyed by most students, and some truly outstanding titration results are achieved. Scheduling the program during the December 26-31 period seems to be ideal since most high school students are not occupied with other activities. Acknowledgment We are grateful to the Dow Chemical Company Foundation for financial support of this program.
Pimentel. G. C.: Coonrod, J. A. Opportunltles In Chemistry Today and Tomorrow, National Academy: Washington, DC, 1987.
Volume 68
Number 7
July 1991
549
