Class 11 Physics Kinetic Theory Kinetic Theory of an Ideal Gas

Kinetic Theory of an Ideal Gas

Basis of Kinetic Theory: -

  1. Molecules of gas are in incessant random motion,colliding against one another

andwith the walls of the container.

  1. All collisions are elastic.
  2. Total Kinetic energy is conserved.
  3. Total momentumis conserved.
  • In case of an elastic collision total Kinetic energy and momentum before collision is equal to the total Kinetic energy and momentum after collision.

What does Kinetic Theory tells?

  1. At ordinary temperature and pressure the molecular size is very small as compared to inter molecular distance between them.
  2. In case of gas, molecules are very far from each other and the size of molecules is small as compared to the distance between them.
  3. As a result, interaction between them is negligible. As there is no interaction between the molecules, there will be no force between the molecules.
  4. As a result molecules are moving freely as per newton’s first law of motion.
  5. The molecules should move along straight line but when they come closer they experience the intermolecular forces and as a result their velocities change.
  6. This phenomenon is known as collision.These collisions are elastic.

Molecules moving randomly


Molecules colliding with each other


Molecules change their direction after colliding

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