ABSTRACT
The fundamental principles of molecular kinetic theory were deduced by Daniel Bernoulli. The molecular kinetic theory is based on the postulation of an ideal gas. The ideal gas properties are consistent with several assumptions that simplify the physical model and the calculation of respective quantities. The assumption of equal pressure in any direction is possible only in a gas system with small dimensions, where the gravitation forces acting on molecules do not make a notable difference. The volumetric expansion of ideal gases, originally studied by Joseph Louis Gay-Lussac and Jacques-Alexandre-Cesar Charles, is an isobaric process at which gas states are determined by just two variables: volume and temperature, while pressure and gas amount are constant. Molar masses of gases and vapors are essential in the calculation of vacuum physical processes. Quantum mechanics is based on increasing/reducing the energies of particles in gas systems only by certain finite amounts, termed quanta.
