|Also called: perfect gas a hypothetical gas which obeys Boyle's law exactly at all temperatures and pressures, and which has internal energy that depends only upon the temperature. Measurements upon real gases are extrapolated to zero pressure to obtain results in agreement with theories relating to an ideal gas, especially in thermometry|
ideal gas n.
A gas that, when kept at a constant temperature, would obey gas laws exactly. No known gas is an ideal gas.
|ideal gas (ī-dē'əl) Pronunciation Key
A hypothetical gas whose molecules bounce off each other (and the boundaries of their container) with perfect elasticity and have negligible size, and in which the intermolecular forces acting between molecules not in contact with each other are also negligible. Such a gas would obey the gas laws (such as Charles's law and Boyle's law) exactly at all temperatures and pressures. Most actual gases behave approximately as ideal gases, except at very low temperatures (when the potential energy of their intermolecular forces is high relative to the kinetic energy of the molecules and becomes significant), and under very high pressures (when the molecules are packed so close together that close-range intermolecular forces become significant).