The Kinetic Molecular Theory
of Ideal Gases

Return to KMT & Gas Laws Menu


These statements are made only for what is called an ideal gas. They cannot all be rigorously applied (i.e. mathematically) to real gases, but can be used to explain their observed behavior qualitatively.

1. All matter is composed of tiny, discrete particles (molecules or atoms).

2. Ideal gases consist of small particles (molecules or atoms) that are far apart in comparison to their own size. The molecules of a gas are very small compared to the distances between them.

3. These particles are considered to be dimensionless points which occupy zero volume. The volume of real gas molecules is assumed to be negligible for most purposes.

This above statement is NOT TRUE. Real gas molecules do occupy volume and it does have an impact on the behavior of the gas. This impact WILL BE IGNORED when discussing ideal gases.

4. These particles are in rapid, random, constant straight line motion. This motion can be described by well-defined and established laws of motion.

5. There are no attractive forces between gas molecules or between molecules and the sides of the container with which they collide.

In a real gas, there actually is attraction between the molecules of a gas. Once again, this attraction WILL BE IGNORED when discussing ideal gases.

6. Molecules collide with one another and the sides of the container.

7. Energy can be transferred in collisions among molecules.

8. Energy is conserved in these collisions, although one molecule may gain energy at the expense of the other.

9. Energy is distributed among the molecules in a particular fashion known as the Maxwell-Boltzmann Distribution.

10. At any paticular instant, the molecules in a given sample of gas do not all possess the same amount of energy. The average kinetic energy of all the molecules is proportional to the absolute temperature.


Return to KMT & Gas Laws Menu