Kinetic Molecular Theory Of Gases
The postulates or assumption of Kinetic molecular theory of the gases are as follows:
- · Gases contain atoms or molecules, as large no. of identical particles. These atoms or molecules are at large distances from each other, so that volume of gases is very high as compared to actual Volume of all molecules of gases. ‘Great compressibility of the gases is explained by these assumptions’.
- · Gases occupy all available space by expansion because at ordinary pressure and temperature there are no attractive forces between gas particles.
- · Gas particles always move in random and at constant motion because if gas particles are at rest and they occupy fixed positions then gas would have fixed shape, which is not observed at all.
- · Gas particles move in straight lines in all the possible directions. During random motion these particles collide with each other and also collide with the walls of the container of the gas. As a result of this collision of gas particles with wall of the gas container pressure is exerted by gas.
- · Collision between the gas molecules is perfectly elastic. It means total energy of the molecules don’t change that is It remains same before and after collision. Individual energy of the molecules may change due to exchange of energy between the colliding molecules, but sum of energies of all molecules remains same.
- · Molecules of the gas move with the different speeds and their individual speed goes on changing due to collision of molecules but at particular temperature, distribution of speeds of molecules remains constant.
- · Kinetic energy of molecules (of the gas) is directly proportional to absolute temperature because on heating gas at fixed volume, its pressure increases. As on heating molecules moves with more speed and strike with walls of the container more rapidly, so exerts more pressure.