Kinetic Theory of gases
Gas molecules behave somewhat differently than molecules of solids or liquids. Particles of gases carry
a great deal of kinetic energy, which keeps them in constant motion. Temperature, pressure, volume and the number of moles of
molecules in a container affects their behavior.
Temperature and pressure are macroscopic properties of gases. These properties are related to molecular motion, which is a microscopic phenomenon.
The kinetic theory of gases correlates between macroscopic properties and microscopic phenomena. Kinetics means the study of motion, and in this case motions of gas molecules.
At the same temperature and volume, the same numbers of moles of all gases exert the same pressure on the walls of their containers. This is known as Avogadro's principle which implies that same numbers of moles of gas have the same number of molecules.
Postulates of the Kinetic Theory of Gases:
- The molecules in a gas are small and very far apart. Most of the volume which a gas occupies is empty space.
- Gas molecules are in constant random motion. Just as many molecules are moving in one direction as in any other.
- Molecules can collide with each other and with the walls of the container. Collisions with the walls account for the pressure of the gas.
- When collisions occur, the molecules lose no kinetic energy; that is, the collisions are said to be perfectly elastic. The total kinetic energy of all the molecules remains constant.
- The molecules exert no attractive or repulsive forces on one another except during the process of collision. They move in straight lines between the collisions.