The motion of gas molecules is also called thermal motion because it is directly related to the temperature of the gas. According to the kinetic theory of gases, the average kinetic energy of gas molecules is directly proportional to the absolute temperature of the gas. This means that as the temperature of a gas increases, the average speed of its molecules also increases.

The random motion of gas molecules is what causes the pressure of a gas. When gas molecules collide with the walls of their container, they exert a force on the walls. The greater the number of collisions per unit area, the greater the pressure of the gas. Since the number of collisions per unit area increases with temperature, the pressure of a gas also increases with temperature.

Thermal motion is also responsible for the diffusion of gases. Diffusion is the process by which gas molecules spread out from an area of high concentration to an area of low concentration. This occurs because gas molecules are constantly moving and colliding with each other, and these collisions cause them to change direction and spread out.

Understanding thermal motion is essential for understanding the behavior of gases. It is a fundamental concept in thermodynamics and fluid mechanics, and it has applications in many fields of science and engineering.