 # CBSE Class 11 Physics Notes Chapter 13 Kinetic Theory

## What is Kinetic Theory of Gas?

The kinetic theory of gases explains the behavior of molecules, which should further explain the behavior of an ideal gas. Ideal Gas equation consists of the pressure (P), volume (V), and temperature (T) of gases at low temperature and the equation is: PV = nRT

Where n = number of moles in the gas R = gas constant having value 8.314JK−1mol−1

Now, any gas following this equation is termed as an ideal gas. Below are some certain assumptions that we consider for describing ideal gas behavior. ### What are the Assumptions of Kinetic Theory of Gases?

• All gas molecules constantly move in random directions.
• The size of molecules is very less than the separation between the molecules
• The molecules of the sample do not exert any force on the walls of the container during the collision when the gas sample is contained.
• It has a very small time interval of collision between two molecules, and between a molecule and the wall.
• Collisions between molecules and wall and even between molecules are elastic in nature.
• Newton’s laws of motion can be seen in all the molecules in a certain gas sample.
• With due course of time, a gas sample comes to a steady state. The molecule’s distribution and the density of molecules do not depend on the position, distance and time.

In-depth Reading: Kinetic Theory Of Gases

### What is law of equipartition of energy?

According to this law, when a system is in equilibrium provided the temperature is absolute, the total energy tends to be distributed evenly in the various energy modes of the absorption. Each translational and the rational degree of freedom represents one energy mode of absorption.

With the help of this law, we can determine the values of molar specific heat of gases.