Kinetic theory

The Kinetic Theory of Gases (formerly dynamic theory of gases ) is a branch of statistical mechanics.

The kinetic theory of gases explains the properties of gases, in particular the gas laws by the idea that gases consist of a very large number of small particles (atoms or molecules) that are in constant motion. The theory leads to an explanation of the microscopic characteristics of temperature and heat, which are defined in thermodynamics by their bulk properties.

Already in the 17th century physicists suspected as Francis Bacon, that heat is a form of movement. The first person who designed a complete theory was Daniel Bernoulli in 1738. Followed him, among other things Mikhail Vasilyevich Lomonosov, Georges- Louis Le Sage, John Herapath and John James Waterston, but their considerations were largely ignored. It was only from 1860 was the kinetic theory of gases through the work of physicists such as Rudolf Clausius, James Clerk Maxwell and Ludwig Boltzmann wider recognition. However, since they depend entirely on the then considered as a hypothesis real existence of atoms or molecules, it was violently disputed by opponents of this hypothesis until well into the 20th century, inter alia, by Ernst Mach and Wilhelm Ostwald.

The main assumptions of the theory are:

From these assumptions, the kinetic theory of gases developed formulas for pressure, specific heat, speed of sound, diffusion, heat conduction and internal friction, perfectly reflect the observations of ideal gases, leading for example to the first determination of the size, number and mass of the atoms or molecules. By additional additives to the assumptions 3 and 4 and the different behavior of real gases to the kinetic theory of gases was included, as described for example, in van der Waals equation of state.