4.4 The Molecular Dynamics Simulator

Chemical Concept Demonstrated: The kinetic molecular theory

Demonstration:

Watch the molecular dynamics simulator and the metal spheres inside. Increasing the voltage is like increasing the temperature in a container. Study what happens to the frequency of colllisions with the wall as the "temperature" increases and when more spheres are added.

Observations:

    As the "temperature" increases, the spheres hit the edges more frequently.  When more spheres are added, the interparticle collisions are more frequent.  The larger particles that are added move more slowly than their smaller counterparts.

Explanations:

    The kinetic molecular theory is demonstrated by use of the simulator.  The following aspects of the theory can be noted:

•     Gas particles are small compared to the distance between them.
•     Gas particle collisions are elastic.
•     Gas particles are in a state of constant, random motion.
•     The particles all move at different random speeds.
•     The average kinetic energy of any given particle increases with the temperature.
•     The number of collisions increases with the addition of heat or more particles.
•     The length of time a particle can go without colliding with something decreases with the addition of heat or more particles.
•     The collisions between particles and the edge of the simulator represent pressure.  The pressure increases with the addition of heat or more particles.
•     The larger particles move more slowly because, although they are imparted with the same average kinetic energy as the rest of the particles, they are also more massive and need more of this energy to move the same average velocity of the smaller particles.
•     There is an inverse square relationship between the mass of the particles and their average velocity.