JOURNRL OF
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-
ancy effect. Experimental data obtained must be recorded and calculations performed outside of the program. The program has been designed to be used a t several levels and in several different ways. Experiments with solids have been used a s a demonstration a t the middle school level, and for pre-lab preparation a t the college level. I t is appropriate for high school, or first year college courses in general or ~hvsicalscience. chemistw. and uhvsics. ~ i s c o s i t~i ~ o l ~ m e r ~ o l u tis; i o ~nasc i & s h version of a Dropram that was oripinallv develooed for the ADDle 11comp;teF(6). It is a ~ ~ ~ e ks kac kr thai d simulates the preparation of ~olvmersolutions using either standard samples or unknov&in various solvents, and gives their time of flow in an Ubbelhode viscometer, along with information relating to the density of the solution as it might be determined with a Westphal balance. Polymer choices include polystyrene in four solvents, polyrnethylmethacrylate in three solvents, polyisobutylene in two solvents, and polyvinyl alcohol in water a t temperatures from 0' to 50' C.
Figure 3. Simulated determination of the density of a sample of gold (Buoyancy Programs). S u ~ ~ l e m e n tfeatures al include an animation of the owration ofthihmmeter, a &cussion ofthe mathematical relationships involved. and directions for owration of the roer ram. precision of ~ a l c u l a t e dValues is es~en~ially a calculator with the ahilitv to c a m uncertainties in i n ~ u values t through thv calculation, prov~dmguncertainties for calculated results. It is designed to introduce students to the principles involved in the propagation of uncertainty, while-also serving as a resource for preparation of laboratory reports for physical chemistry laboratory. The stack contains three modules, Directions for the operation of the program, Background information about how the uncertainty calculations are performed, and the Calculation module itself. Calculation options include the algebraic operators (+, -,*, i) as well as several function operators, llx, U), lo&), lff, e,&,and xn. Calculated values may be saved for use in subseauent calculations. For claritv to beginning students, uncekainties are given to two sibificant fig&, and results of calculations are given to the same number of decimal places a s the input ialues.
About This Issue
Study has been used effectively with both high school and colleee-level introductow chemistrv students. ~ i l ~isi abn updatei version i f a popular Macintosh While souhisticated enough for use in ~ .Dropram. . h"v s i c a l chemistry and spectroscopy courses, it includes simple exa m ~ l e sthat are apurouriate to introduce high school or chemistry stud& to molecular vibrations. Now running under System 7 with colorized atoms, it is an ideal lecture demonstration tool for anyone who wants to get across the idea that molecules vibrate and that their overall vibrations can be understood in terms of a limited number of simpler motions. Buoyancy Programs and Viscosity of Polymer Solutions are laboratory simulations originally written for the Apple I1 that might be used to supplement or replace a real laboratory experiment. Though aimed a t different levels (Buovancv Promams for introductorv courses and Viscosity o r ~ o l $ n e iolutions r for advancei Physical Chemistry, Polvmer Chemistrv, or Material Science) both accuratelv simulate ihc l;rInn~ntoryexperience. Precision of Calculated Values is a useful utilitv promam for any chemist. It might be used in a lecture or iabor&ory a s a demonstration to introduce students to the importance of significant digits and uncertainty in measurements as well a s in physical chemistry and other upper division laboratory courses when students must routinely consider the effects of uncertainty in measurements. It is as simple to use a s a n ordinary scientific calculator. Hardware Requirements Software in Series C of JCE: Software requires a n Apple Macintosh comuuter with a hard drive and a SuoerDrive floppy disk drive. System software version 6.0.7 later is required. If you are running System 7 or MultiFinder, a t least 2 MB of RAM is required. In addition both Lake Study and MolVib 2.0 require a Macintosh I1 or better, System 7 or higher, and a t least 4 MB RAM. A 256 color monitor is not required, but strongly recommended. Buoyancy Programs, Viscosity of Polymer Solutions, and Precision of Calculated Values all require Hypercard or Hypercard player version 2.0 or higher. At least 2 MB of RAM with System 6 or 4 MB of RAM with System 7 are required. Installation of Lake Study requires approximately 1,600 KB of free hard disk space; MolV~b 200 KB, Buoyancy Programs 300 KB, Viscosity of Polymer Solutions 400 KB, and Precision of Calculated Values 200 KB.
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Citations
Electronic Dellvery of lnformatlon Information about any of our issues (including abstracts, descriptions, updates, etc.) is also available on Internet Gopher: jchemed.ehem.wise.edu and on our World Wide Web site using a browser such as Netscape or Mosaic at: http:/ljehemed.chem.wisc.edu.
John W. Moore, Editor Nancy S. Gettys, Technical Editor University of Wisconsin-Madison Madison. WI 53706
Lake Study for Macintosh is a new version of a popular JCE: Software Dromam for Windows. Our subscribers reauested it. ar;d we &e very pleased to be able to offer this exce~entin& duction to scientific investigation to Macintosh users. Lake Volume 72 Number 6 June 1995
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