2000 CONFCHEM The Use of Computer Simulations in General Chemistry . By Chung Chieh and Newman S.K. Sze, Department of Chemistry, University of Waterloo, Waterloo, Ontario, Canada N2L3G1

# 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

## 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 H2, N2, H2O, CO2, 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