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COMPUTER ANIMATIONS AND SIMULATIONS IN GENERAL CHEMISTRY

By *Chung Chieh* and *Newman K.S. Sze*,
Department of Chemistry,
University of Waterloo, Waterloo, Ontario,
Canada N2L 3G1
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Abstract

Computer simulations and animations are usually excellent tools for education.
Animations show step-wise sequences of diagrams, numbers, or images to
illustrate complicated concepts or theories. Simulations, on the other hand,
are imitations of systems for users. The user enters or alters certain
parameters, and the computer will reveal the consequences or changes.
Some random or uncertain elements are involved in simulations.
Experiments using real systems are the best ways to explore science,
and simulations offer students alternative ways to discover when real
systems are not available or impossible to setup.
A system may be set up according to some theories. For example, van der
Waals equation can be used for real gases to illustrate how real gases
differ from *the ideal gas*. These equations are implemented in a
Java applet to simulate a system for a user to explore the difference.
From this simulation, a user is asked to find out conditions in which
the ideal gas law gives results within a set error limit.

Using graphical representation, we illustrate how Van der Waals equation
deviates from real gases, especially in conditions when another phase
is present. Gases such as H_{2}, N_{2}, H_{2}O,
CO_{2}, *etc* are being considered currently in our Java
applet to be used in the paper.

Differential equations are excellent for defining a system. Instead of
solving these differential equations for explicit form, numerical methods
may be applied. Implementation of numerical method is very easy using
computers, and we will share our experience in using numerical methods
for simulations.

Monte Carlo Simulation is another popular method used to explore systems
involving large ranges of parameters. Instead of covering the entire range,
results of some random points are calculated, and the results extended to
the entire range. Some examples of Monte Carlo simulations will be presented.

Some years ago, one of us taught a course *Application of Computers in
Chemical Problem Solving*. Programs have been written to illustrate
animations and simulations, and we will outline some of these projects.

E-mail: cchieh@uwaterloo.ca