Chemical Education Today
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The Physics Teacher by Volker B. E. Thomsen
TPT Featured Articles
The Physics Teacher (TPT ) is dedicated to introductory physics education at the high school and university levels. Many articles are also of interest to teachers of chemistry at this level. Some examples from recent issues, covering a variety of topics, are presented here. The article by Francis Hart, “A Microcomputer-Based Phase-Change Experiment” (TPT, 1998, 36, 98), is an interesting addition to the various introductory phase-transition experiments. It is basically an exercise in photometry using the Vernier universal lab interface (http://www.vernier.com). A beaker of Crisco shortening, previously heated to 60 ºC, is placed between a flashlight and a light sensor. The temperature is monitored by a separate sensor inserted in the beaker. After about a halfhour, there is a sharp drop in the light throughput as the cooking oil solidifies. “A Closer Look at the Spectrum of Helium” (TPT, 1998, 36, 172) by Michael C. Lo Presto presents a discussion of the helium spectrum that is appropriate for the introductory level. Student measurements of the spectral line wavelengths generally agree with tabulated values to better than 1%. Some
“A Microcomputer-Based Phase-Change Experiment” by Francis Hart (TPT, 1998, 36, 98) “A Closer Look at the Spectrum of Helium” by Michael C. Lo Presto (TPT, 1998, 36, 172) “True Lines” by Arthur Mersereau and James Metz (TPT, 1998, 36, 174)
theory, perhaps not normally encountered at this level, is presented without the use of mathematics. Have you ever been frustrated by the usual least-squares curve fit that refuses to go through the origin, no matter how many (0,0) data points you add? The note, “True Lines” (TPT, 1998, 36, 174) by Arthur Mersereau and James Metz presents the proper algorithm for this curve fit, including the correlation coefficient. This provides an oftentimes more realistic curve fit, as shown in an example. An introduction to the interferometer, a device often used to measure wavelengths, can perhaps best be accomplished by starting with sound rather than light waves. The article, “Ultrasonic Interferometers” (TPT, 1998, 36, 249) by Thomas B. Greenslade, Jr. and Joshua A. Mason, a Kenyon College (OH) sophomore, provides a series of experiments to introduce this important instrument. Mario Capitolo presents a quick lecture demonstration of the liquid–vapor–solid transitions of water at low pressures in his article, “Phase-Change Demonstration-Instant Gratification” (TPT, 1998, 36, 349). Using an overhead projector and a transparent bell jar with base, the water can be seen to boil within seconds and then, shortly thereafter, turn opaque as ice forms—all this in less than two minutes after starting the vacuum pump. The trick, according to the author, is to use only a small amount of water, about 0.5 ml. Although not discussed in this note, the demonstration of the liquid–vapor transition can be made quantitative by adding a manometer to the system, using more water, and applying the Clausius–Clapeyron equation. The calculation, suitable for high school students, is given in a February 1997 note (TPT, 1998, 35, 98) and was reported previously in this column (1).
“Ultrasonic Interferometers” by Thomas B. Greenslade, Jr. and Joshua A. Mason (TPT, 1998, 36, 249)
Literature Cited
“Phase-Change Demonstration-Instant Gratification” by Mario Capitolo (TPT, 1998, 36, 349)
Volker Thomsen is an applications scientist at Spectro Analytical Instruments, Inc., 160 Authority Dr., Fitchburg, MA 01420.
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1. Thomsen, V. J. Chem. Educ. 1997, 74, 897.
Journal of Chemical Education • Vol. 76 No. 1 January 1999 • JChemEd.chem.wisc.edu
