Chemical Education Today
In This Issue The Cover: Supercritical CO 2
Organic Holiday Treat
The coffee beans on this month’s cover, together with the phase diagram for carbon dioxide, represent one of the applications of supercritical fluid extraction discussed by Phelps, Smart, and Wai beginning on page 1163. The three photographs of carbon dioxide that are superimposed on the phase diagram show a liquid–vapor equilibrium below the critical temperature and pressure, CO2 at the critical point, and supercritical fluid CO2. By adjusting temperature and pressure the solvent properties of supercritical CO2 can be made similar to those of pentane, benzene, chlorinated hydrocarbons, chlorofluorocarbons, and pyridine, to mention only a few. Thus it can replace many of these solvents in many applications. Environmental and health concerns are often strong motivators toward using supercritical fluids instead of some of the solvents mentioned, and new applications such as extraction of metals and reaction solvents are being explored.
Caffeine, Colas, and Juice Our preoccupation with caffeine continues on pages 1169–1172, where zone electrophoretic determination of caffeine in beverages is described by Conte, Barry, and Rubinstein and two caffeine extraction experiments are presented: from coffee beans by Adam, Mainwaring, and Quigley and from tea by Hampp. Cola beverages are the subject of three more papers on pages 1172–1176. Lozano-Calero, Martín-Palomeque, and MadueñoLoriguillo report a chromatographic separation of phosphoric acid and also describe use of a phosphomolybdenum blue for determination of phosphorus. Bello and González use nonsuppressed ion chromatography to analyze colas for phosphate. A caffeine-free beverage, orange juice, is used to help provide electric juice to a clock by Kelter, Carr, Johnson, and Castro-Acuña on page 1123. Interesting as a classroom demonstration, the orange juice clock can be explored more quantitatively by using a high-impedance voltmeter, and the authors show that it actually ticks on its own!
We have provided what we hope will be a holiday treat for the organic chemists among our readers. On pages 1171, 1181, and following page 1185, we provide a variety of experiments that should delight true organikers. They range from studies of compounds found in foods and fragrances, through spectroscopy and drug preparation, to proton NMR of terpenes. Also included for organic chemists are a discourse on “amyl” (page 1127), theme-based organic lab modules (page 1130), a survey of which organic topics are thought most important by medical school faculty (page 1153), and a Sherlock Holmes mystery based on organic chemistry (page 1157). Make a New Year’s resolution to sample this holiday treat next semester.
Laboratory Computing LabVIEW is software that facilitates experimental design and is widely used in both industrial and academic research labs. That it can be used quite effectively to help students learn experimentation and instrument construction is attested to by the papers on pages 1103– 1116. Gostowski uses LabVIEW in an Advanced Instrumental Methods course that enables students to construct a simple analytical instrument. At Carleton College, Drew has integrated LabVIEW at all levels of the curriculum: computer-assisted experiments in lower-division labs and hands-on experience with design and operation of computer-controlled instruments in more advanced courses. Muyskens, Glass, Wietsma, and Gray describe data acquisition experiments that use a variety of sensors and are appropriate at various levels of the curriculum. Physical chemistry laboratory and analytical chemistry research can also be enhanced using LabVIEW according to Ogren and Jones, who use interface boards in Macintosh computers. Those who are interested in incorporating computerized instrument and experiment control techniques at any level of the curriculum will find excellent reading here.
Chemical Education Today Getting To Know Our Students Better What misconceptions are students likely to hold regarding electrochemistry? Go to pages 1145–1149 and read what Ogude and Bradley have discovered. They find two main areas where students have difficulty: inconsistent terminology (anode, cathode, etc.) and lack of knowledge of what individual components of a cell (voltmeter, salt bridge, etc.) actually do. Immediately following (on pages 1150–1153) is a study of the correlation between scores on the mathematical SAT and grades in introductory chemistry. Spencer finds that SAT-M scores correlate significantly with grades, and that gender, experience in college, and ethnic background do not. For faculty whose students are likely to study biochemistry in medical school, Scimone and Scimone have surveyed selected biochemistry faculty from a large number of medical schools to find what topics they think are important in general chemistry and in organic chemistry. The results reported on pages 1153–1156 may surprise you.
Two reports from other journals indicate that there is lots of useful information for chemical educators out there. Judd continues her guide to the Internet on page A304 by showing how to develop your own table of contents to this ever-growing and ever-changing resource for teachers and students. Chemistry and Biology is a quite different resource, and one that has clearly captured the imagination of its rapporteur, Walsh (pages A305–A306). The attractions of this journal are spectacular graphics and articles written for those who have little background in an area of research but are willing to expend some time and effort to learn the latest theories and information. Another timely topic is the recently adopted National Science Education Standards. On pages A307–A308 Ware reports that chemistry is found not only in the physical science section of the standards, but in most other areas as well. Also significant is the importance placed on inquiry as an integral component of content. Those who are planning how to implement the standards will find this commentary very helpful.
Vol. 73 No. 12 December 1996 • Journal of Chemical Education
A287
