An ideal gas has a number of properties; real gases often exhibit behavior very close to ideal. The properties of an ideal gas are:

1. An ideal gas consists of a large number of identical molecules.

2.The volume occupied by the molecules themselves is negligible compared to the volume occupied by the gas.

3.The molecules obey Newton's laws of motion, and they move in random motion.

4.The molecules experience forces only during collisions; any collisions are completely elastic, and take a negligible amount of time.