An ideal gas, also known as a perfect gas, is a theoretical concept of a gas which would obey the gas laws exactly. Such a gas would consist of perfectly elastic molecules, the volume occupied by the actual molecules, and the forces of attraction between them, being zero or negligible.
Ideal gas law
pV = nRT,
where n is the number of moles of the gas present and R is the so-called gas constant.
The ideal gas law implies that at constant temperature (T), the product of pressure and volume (pV) is constant (Boyle's law) and at a constant pressure, the volume is proportional to the temperature (Charles' law). See also equation of state.