Basics of Kinetic Theory of Gases

Basics of Kinetic Theory of Gases

The kinetic theory of gases is used as a model to understand the thermodynamic behaviour of gases. The model is identical to the submacroscopic particles that have random, constant, and rapid motion.

History of Kinetic Theory of Gases

The basis for the kinetic theory of gases was laid in the year 1738 when Daniel Bernoulli published Hydrodynamics. In his work, he explained that gas consists of a large number of molecules that move in all the directions such that their movement can be felt in the form of gas pressure. This is known as heat and is caused due to the motion of molecules. The theory was not accepted immediately and took a while since conservation of energy was yet to be established.

The kinetic theory of gases helped in establishing many principle concepts related to thermodynamics. Using this concept one can understand the macroscopic properties of gases, which includes temperature, pressure, and volume and other properties related to transport such as mass diffusivity, thermal conductivity, and viscosity. Brownian motion is also explained using the kinetic theory of gases. Gas laws such as Charle’s law and Boyle’s law are explained with the help of the concept of the kinetic theory of gases.

What is Kinetic Theory of Gases?

Kinetic theory of gases is defined as the theory in which the gas particles move in a straight line with high average velocity exerting pressure on the walls of the container.

There are a few assumptions and postulates related to the kinetic theory of gases that are discussed further in this article.

Kinetic Theory of Gases Assumptions

  • Gases consist of a large number of tiny particles and these particles are far apart when compared to their size.
  • The gas particles collide with each other and with the walls of the container and these collisions are elastic, that is the net loss of kinetic energy is zero.
  • The gas particles have a continuous, rapid, and random motion as they possess kinetic energy.
  • The total kinetic energy of the particles is proportional to the absolute temperature.
  • The molecules obey Newton’s laws of motion.
  • The density of these particles is independent of position, time, and distance.

Postulates of Kinetic Theory of Gases

Following are the postulates of the kinetic theory of gases:

  • Gas molecules exert pressure on the walls of the container.
  • The ratio of space and volume is negligible.
  • There is a continuous motion of the particles as there is a lot of space available between them.
  • The particles experience an elastic collision.
  • The average kinetic energy of the particles can be determined by using the temperature.

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