Postulates of the Kinetic Theory of Gases
1 The molecules in a gasA state of matter in which a substance occupies the full volume of its container and changes shape to match the shape of the container. In a gas the distance between particles is much greater than the diameters of the particles themselves; hence the distances between particles can change as necessary so that the matter uniformly occupies its container. are small and very far apart. Most of the volume which a gas occupies is empty space.
2 Gas molecules are in constant random motion. Just as many molecules are moving in one direction as in any other.
3 Molecules can collide with each other and with the walls of the container. Collisions with the walls account for the pressureForce per unit area; in gases arising from the force exerted by collisions of gas molecules with the wall of the container. of the gas.
4 When collisions occur, the molecules lose no kinetic energyA system's capacity to do work.; that is, the collisions are said to be perfectly elastic. The total kinetic energy of all the molecules remains constant unless there is some outside interference with the
5 The molecules exert no attractive or repulsive forces on one another except during the process of collision. Between collisions, they move in straight lines.
These postulates are covered in more detail on Kinetic Theory of Gases: Postulates of the Kinetic Theory.