1.Introduction:

           Kinetic theory of gases is about the study of Molecular behaviour of gases which leads to the understanding of macroscopic properties of the gases such as their pressure, volume, temperature, density, kinetic energy in terms of temperature, etc. The movement of molecules are random and complicated. The number of molecules are very large in a sample of gas and it is difficult to apply the laws of Mechanics to each and every molecule independantly. However to understand the macroscopic properties of a gas, the individual molecules are not important. The laws of Mechanics can be applied statistically to the whole gas. This approach made the Kinetic theory of gases simple. In gases, the molecules are quite far away compared to their sizes and interactions between them are very weak compared to liquids and solids. This further simplifies the mathematical difficulties.

Ideal Gas Equation

            The gases at low pressures and at temperature far above their condensation point obeys the following relation between their pressure ,  volume and temperature ,
                                ............................... ( 1 )
Here, n - is the number of moles and R = 8.314 J/mol.K.  R is called Universal Gas Constant. Gases which obey the eqn(1) are called ideal gases.

           The above relation can be verified by performing a simple experiment. Let us take a baloon filled with a gas of mass ‘m’ at thermal equilibrium. If the baloon is squeezed from one end, the gas is forced to take a smaller volume and its pressure increses.