Kinetic Molecular Theory Of Gases

Main postulates

• 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 × 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 speeds.
• Gas molecules collide with each other and with the walls of container. Their 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.