Kinetic Molecular Theory of Gases


  Main postulates of kinetic molecular theory of gases are as under:
 A gas consists of very small microscopic particles called ‘molecules’. Depending upon the nature of      gas each gas molecule may consists of an atom or group of atoms. Molecules are in a state of      continuous motion.
 All the molecules of a gas are in stable state and are considered identical.
 Any finite volume of a gas consists of very large number of molecules.
At S.T.P. there are 3 x 1025 molecules in a cubic meter.
 The molecules are wide separated from each other as compared to their own dimensions.
 The diameter of a molecule is about 3 x 10-10 meter.
 Gas molecules move in straight line in all possible directions (random movement) with various
 Gas molecules collide with each other and with the walls of container. There collisions are perfectly      elastic in nature.
 Gas molecules when collide with the walls of container, they transfer their momentum which appears      as pressure of gas.
 Molecules of an ideal gas exert no force of attraction or repulsion on one another except during      collision.
 The average kinetic energy of gas molecules is directly proportional to absolute temperature.
 At a given temperature, the molecules of all gases have the same kinetic energy.
 Newtonian mechanics is applicable to molecular motion.