Kinetic Theory Of Gases

1.   

              Newtonian mechanics can be applied to the molecular collision

2.      Gases are made of large number of molecules which are alike and different from molecules of other gases. The number of molecules in any given gas is constant  at any time.

3.      The size of the molecules are negligible compared to size of their container. They are mere point point masses, the distance between the molecules is large compared to their sizes.

4.       The molecules are in constant continuous random motion in all direction colliding with one another and with the hall of their containing vessels.

5.      The collision between gases and the hall of their container is perfectly elastic.

6.      There is no force of attraction or repulsion between the gases except when they pt collide with each other or with hall of their container.

7.      The average kinetic energy of translation of a molecules is proportional to their average kinetic energy.

The above theory is for ideal or perfect gas, real gases differ from ideal or perfect gas, they tend to behave differently at lower temperature and higher pressure, the theory also fail with heavy gases where their molecular size is important.  Real gases only behave like ideal gases at higher temperature and lower pressure, real gases can undergo phase transition at low temperature and higher pressure whereas ideal gas cannot.
 from the kinetic theory of ideal gases , the density of the gas is sum of the individual masses of the molecules divided by the volume of the gas,  as the molecules of the gas collide with each other and the hall of the container, they develop a pressure which is equal to the force exerted from the impart momentum  divided by the area occupied by the gas.

 The temperature of the gas is the average kinetic energy of the molecules of the gas undergoing the continuous rapid random motion.  the higher the temperature of the gas the higher the rate of the motion,