What is kinetic theory?

The kinetic theory applies to liquids, gases, and solids. The explanation of the kinetic theory, however, is best illustrated in gases.

The kinetic theory assumes that all gases are made up of tiny particles called molecules. The distance separating the molecules from one another is very large compared to the size of the molecules themselves. The theory also assumes that the molecules are in a constant state of motion, except at absolute zero. Because they are in mo­tion, they collide with one another and with the walls of any container. The collisions with the walls cause pressure to be exerted on the container. The molecules are assumed to be perfectly elastic so that when they collide, they rebound without any loss of energy. The velocity of the molecules depends on the temperature. As the temperature increases, the velocity of the particles increases.