Kinetic-Molecular Model of an Ideal Gas

Definition: Kinetic-Molecular Model of an Ideal Gas

The kinetic-molecular model of an ideal gas is an idealisation of gases which makes the following assumptions:

Axiom: Assumptions of the Kinetic-Molecular Model

1. The gas is comprised of a very large number of identical particles, each with mass $m$, which are enclosed in a container with volume $V$.
2. These particles are very small compared to the size of the container and to the average distance between particles and therefore behave as point masses.
3. These particles are moving constantly and occasionally colliding elastically with the walls of the container.
4. The container walls are rigid, infinitely massive and thus unable to move.

An ideal gas in thermodynamics is parameterized in two different ways:

• Microscopically, through the positions and momenta of all of its particles - the physical state of the gas with respect to this microscopic parameterization is its microstate.
• Macroscopically, through its pressure $p$, temperature $T$, volume $V$ and number of particles $N$ - the physical state of the gas with respect to this macroscopic parameterisation is its macrostate.