(1) The gases actually found in nature are called real gases.
(2) They do not obey gas Laws.
(4) The quantity PV/RT is called the compressibility factor and should be unit for an ideal gas.
(i) Volume correction : Due to finite size of molecule, a certain portion of volume of a gas is covered by the molecules themselves. Therefore the space available for the free motion of molecules of gas will be slightly less than the volume V of a gas. Hence the effective volume becomes (V – b).
(ii) Pressure correction : Due to intermolecular force in real gases, molecules do not exert that force on the wall which they would have exerted in the absence of intermolecular force. Therefore the observed pressure P of the gas will be less than that present in the absence of intermolecular force. Hence the effective pressure becomes (P+( a/V2))