Behavior of all the gases is similar to each other. To explain the similar behavior of all the gases, a model was devised. This model is known as kinetic molecular theory of gases.
The postulates of this theory are:
- Gases are made up of molecules, which are far apart from each other. Spaces between them are very large as compared to their sizes.
- The actual volume of the molecules is negligible as compared to their volume, which they occupy in gaseous state.
- The molecules of gases neither attract nor repel each other.
- The molecules of gases move continuously in haphazard motion but in straight lines.
- The collisions of gas molecules with each other and with the walls of the container are perfectly elastic.
- The pressure of a gas is the result of the collision between the molecules and the walls of the container.
- Due to motion molecules of gases possess kinetic energy equal to 1/2 mv2.
- The average kinetic energy and average speed of the molecules of a gas is directly proportional to its absolute temperature.
- At the same temperature, molecules of all the gases have the same average kinetic energy.