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Chemical € ducation: Software Abstract for Volume 7 C, Number 1 Lake Study for Macintosh David M. Whisnant Wofford College Spaltanburg. SC 29303-3663 James McCormick and Paul Wagner Univerdty of Wisconsin-Madison Madison, WI 53706-1396
Lake Study for Macintosh is a new version of a program previously published by JCE: Software for Windows computers (1).Both the Windows and Macintosh programs are based on a n Apple I1 program by the same name (2,3).Lake Study is a two-part computer simulation designed to involve non-scientists with the scientific method. It allows them to collect data, formulate hypotheses, and test the hypotheses with controlled experiments in the laboratory. Students are assigned the task of discovering the cause of breathing diff~cultiethat are killing young fishin alake in the first part of the simulation. They may collect water samples from the lake, analyze them, and then compare their results with library references on toxicity of the pollutants. Students may also look a t the fish themselves, and consult simulated colleagues. Having done this, they can develop a hypothesis about the problem. I n the second part of the experiment, students can do controlled experiments to determine which of the two hypotheses is more likely. The fact that different students reach different initial hypotheses is a good mechanism for inducing classroom discussion about the facts that support each hypothesis and their logical interpretation.
MolVib 2.0 Daniel Huber Metrohm, Ltd. CH-9100 Herisau, Switzerland Paul Wagner University of Wisconsin-Madison Madison, WI 53706-1396
MolVib 2.0 is a n update of a program previously published by JCE:Software (4). The new version is System 7 compatible and includes color graphics and other interface improvements. MolVib allows you to display a vibrating molecule on your computer screen and view it from whatever position you choose. You can choose one of several molecules available a s examples and then select each normal vibrational mode from a menu. Modes may be animated individually, or mixed to demonstrate the equivalence of degenerate vibration. Animation speed can be varied in order to see the motion more clearly, and the molecule can be rotated in three dimensions so that the vibration can be ohsewed from any viewpoint. Center-of-mass and Eckhart (angular momentum) conditions are always fulfilled during the motion so that mass effects such a s isotopic substitution can be demonstrated. H20, HDO, and D20 can easily be compared, for example. 492
Journal of Chemical Education
Figure 1. Screen from Lake Study showing results of a controlled experiment on fish mortality.
Figure 2. Animation of the asymmetric stretching vibration of water (MolVib2.0). I n addition to the graphic output, you can obtain numeric results for each vibration. MolVib can be used appropriately a t several levels. For introductory students it provides a convenient way to illustrate how molecules vibrate and to show difference in vibrations when isotopic substitutions are made. At a more advanced level it is ~ o s s i b l to e show that if a subsection of a molecule has very different vibrational frequency from the frequencies in the rest of the molecule, that vibrational mode will survive even in the composite molecule. I n physical chemistry and other advanced courses it is possible to examine eigeuvalues and eigenvectors for a given vibrational problem, and these could be compared with results of students calculations.
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Buoyancy Programs; Viscosity of Polymer Solutions; Precision of Calculated Values Gary L. Bertrand University of Missouri-Rolla Rolla, MO
Buoyancy Programs is a set of simulated experiments for determining the densities of solids and liquids adapted to the Macintosh from an earlier program for the Apple I1 (5).In this Hypercard stack, students can perform three types of experiments, one for liquids and two for solids. An animated demonstration is included to introduce the buoy-
