13.2 Kinetic Theory of Gases

13.2 Kinetic Theory of Gases

The kinetic theory of gases describes the molecular composition of the gas and their motion. In this theory, the gas pressure arises due to particles colliding with each other and the walls of the container. It also defines properties such as temperature, volume and pressure, as well as transport properties such as viscosity and thermal conductivity and diffusivity.

The kinetic molecular theory applies to the ideal gases and it has been defined in the previous class. However, the basic assumptions are:

1. Gases consist of very large number of tiny spherical particles that are far apart from one another compared to their sizes.
2. Gas particles are in constant rapid motion in random directions.

Do you know?

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A small 'cube' of air can have as many as $10^{19}$ molecules. Volume of the gas particles is negligible compared to the volume of the empty spaces.

3. Collisions between gas particles and the container walls are perfectly elastic collisions.
4. There are no forces of attraction or repulsion between gas particles until the particles perform collisions with each other.
5. The average kinetic energy of gas particles is dependent upon the temperature of the gas.

For your information

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The mean free path is average distance a moving particle covered before it undergoes a collision that significantly alters its direction or energy.