Gases // Kinetic Theory

Source of image of pixabay

The gases are constituted by particles, which move with entire freedom a few with regard to others and they lack cohesion, although it does not have proper form and they adopt that of the receptacle that contains it, as liquid, the gases it tends to occupy the totality of the volume of the same one.

Animation: mass and constant temperature, Source of image of mastery of Wikimedia Commons

The description of the gaseous state and of the trasformaciones, that you experience the gases they are realized by means of the so called kinetic theory of the gases and it bases on the so-called laws of the gases. The kinetic theory of the gases is based on the conception, that these are composed by atoms or molecules, which move with big rapidity and in directions at random, each of the above mentioned particles possesses a kinetic energy, which depends on his temperature, also he considers, that such particles experience perfectly elastic shocks, that is to say, that when they clash between yes, preserve his speed and the shock does not represent a loss of energy, the above mentioned theory supposes, that the volume occupied by particles, compared with him, which occupies the gas of which they are a part, is despicable, in addition to thinking that the mutual attraction between them is also void.

Robert Boyle (1627-1691), Source of image of mastery of Wikimedia Commons

The time that comes up between collisions they are considered to be so big, that the one that supposes the collision should be admitted like despicable, the shocks of atoms and molecules of one gas are only one of the types of existing shock in the gases, since also they collide with the walls of receptacle that contains it, exercising a force against them, which is a function of the proper shock against the wall, the kinetic energy that it cheers up to the particle. On having been perfectly elastic, the shocks do not suppose loss of kinetic energy, for the particle, if it is an evidence that they change the direction dela speed, of such a way the pressure exercised on the walls of the receptacle is an average force for surface unit.

This law is a simplification of the law of the ideal or perfect gases distinguished for isothermal processes of a certain mass of constant gas, Source of image of mastery of Wikimedia Commons

The description of the behavior of the gases according to his pressure, volume and temperature obeys the call laws of the gases, which they confirm that said magnitudes they are related between if and that coincide with the results of the kinetic theory of the gases. Let's consider first the existing relation between the volume and the pressure of a gas, the above mentioned relation expresses itself by means of the law of Byle-Mariotte, which they affirm for a constant temperature, the pressure exercised by a gas mass on the walls of the receptacle, which contains it is inversely proportional to the volume, which the above mentioned gas occupies.

The law expresses as P.V = constant, for a certain temperature, where P is the pressure and the Vth represents the volume, from point of view of the kinetic theory of the gases, this law is correct, since, after diminishes the volume, which occupies a gas to constant temperature, the atoms or molecules, which compose it must collide with major frequency with the walls, from what it has to increase the pressure.

The relation between the volume and the temperature comes given by the first law of Gay-Lussac, who affirms that for a pressure, which should stay constant, a proportionality exists between the volume that occupies the gas and his temperature, where the relation is V/T = constantly, where the Vth is the volume and T is the absolute temperature, for this motive also this theory it is acceptable, since the increase of the temperature, it does that I increased the energy of the atoms or particles. The above mentioned increase must translate to itself in a major speed and shock more fortresses with the walls of the receptacle, since it is necessary that it increases the volume.

Bibliographical source

General physics - Page 268 for Santiago Burbano de Ercilla, ‎Carlos Grace Muñoz - 2003.

General chemistry. Introduction to the Theoretical Chemistry - Page 257 for Cristóbal Valenzuela Calahorro - 1995.