# Ideal Gas

An ideal gas is a theoretical gas composed of a set of randomly-moving, non-interacting point particles. The ideal gas concept is useful because it obeys the ideal gas law, a simplified equation of state, and is amenable to analysis under statistical mechanics.

At normal conditions such as standard temperature and pressure, most real gases behave qualitatively like an ideal gas. Many gases such as air, nitrogen, oxygen, hydrogen, noble gases, and some heavier gases like carbon dioxide can be treated like ideal gases within reasonable tolerances. Generally, a gas behaves more like an ideal gas at higher temperature and lower density (i.e. lower pressure), as the work performed by intermolecular forces becomes less significant compared with the particles' kinetic energy, and the size of the molecules becomes less significant compared to the empty space between them.

The ideal gas model tends to fail at lower temperatures or higher pressures, when intermolecular forces and molecular size become important. It also fails for most heavy gases, such as many refrigerants, and for gases with strong intermolecular forces, notably water vapor. At some point of low temperature and high pressure, real gases undergo a phase transition, such as to a liquid or a solid. The model of an ideal gas, however, does not describe or allow phase transitions. These must be modeled by more complex equations of state.

The ideal gas model has been explored in both the Newtonian dynamics (as in "kinetic theory") and in quantum mechanics (as a "gas in a box"). The ideal gas model has also been used to model the behavior of electrons in a metal (in the Drude model and the free electron model), and it is one of the most important models in statistical mechanics.

### Other articles related to "ideal gas, gas, ideal":

Relations Between Heat Capacities - Ideal Gas
... This is a derivation to obtain an expression for for an ideal gas ... An ideal gas has the equation of state where P = pressure V = volume n = number of moles R = universal gas constant T = temperature The ideal gas equation of state can be arranged to give ... in molar heat capacities becomes simply R for ideal gases as follows This result would be consistent if the specific difference were derived directly from the general expression for ...
Ideal Gas - Ideal Quantum Gases - Ideal Bose and Fermi Gases
... An ideal gas of bosons (e.g ... a photon gas) will be governed by Bose-Einstein statistics and the distribution of energy will be in the form of a Bose-Einstein distribution ... An ideal gas of fermions will be governed by Fermi-Dirac statistics and the distribution of energy will be in the form of a Fermi-Dirac distribution ...
Accidental Release Source Terms - Accidental Release of Pressurized Gas - Ramskill's Equation For Non-choked Mass Flow
... equation for the non-choked flow of an ideal gas is shown below as equation (1) The gas density, A, in Ramskill's equation is the ideal gas density at the downstream ...
Temperature - Theoretical Foundation - Kinetic Theory of Gases
... The kinetic theory of gases uses the model of the ideal gas to relate temperature to the average translational kinetic energy of the molecules in a container of gas in thermodynamic equilibrium ... defines the translational kinetic energy of a gas molecule as follows where m is the particle mass and v its speed, the magnitude of its velocity ... determine the translational kinetic energies) of the particles in a classical ideal gas is called the Maxwell-Boltzmann distribution ...
Lenoir Cycle - Constant Volume Heat Addition (1-2)
... In the ideal gas version of the traditional Lenoir cycle, the first stage (1-2) involves the addition of heat in a constant volume manner ... the first law of thermodynamics and from the definition of constant volume specific heats for an ideal gas Where R is the ideal gas constant and γ is the ratio of specific heats (approximately 287 J/(kg·K ... The pressure after the heat addition can be calculated from the ideal gas law ...

### Famous quotes containing the words gas and/or ideal:

A new father quickly learns that his child invariably comes to the bathroom at precisely the times when he’s in there, as if he needed company. The only way for this father to be certain of bathroom privacy is to shave at the gas station.
Bill Cosby (20th century)

The ideal of the self-sufficient American family is a myth, dangerous because most families, especially affluent families, do in fact make use of a range of services to survive. Families needing one or another kind of help are not morally deficient; most families do need assistance at one time or another.
Joseph Featherstone (20th century)