Kinetic Molecular Theory
The kinetic molecular theory is used to explain the behavior of gases. Daniel Bernoulli started kinetic molecular theory in 1738. Rudolf Clausius refined the theory in the mid-1800s (1857). It is also known as the theory of moving molecules. This theory provides a model of an ideal gas. However, real gases deviate from ideal gases.
The kinetic molecular theory of gases is based on the following assumptions/postulates:
Gases are made up of individual molecules that are in constant rapid motion.
The molecules of a gas are farther apart than molecules of a liquid or solid.
The constantly moving gas molecules possess kinetic energy (enery of motion). The average kinetic energy depends on the temperature. The higher the temperature, the higher the kinetic energy and the faster the particles are moving.
Collisions between gas particles or collisions with the walls of the container are elastic. That means the rapidly moving gas molecules collide with each other and the walls of the gas container without any loss of kinetic energy.
The collision of gas molecules with the walls of the gas container results in pressure.
Gas molecules occupy no volume.
The individual gas molecules have no attraction or repulsion for each other.
The average kinetic energy of a molecule is 3kT/2. (T is the absolute temperature and k is the Boltzmann constant.)