Ideal vs Real Gases 1

 

Ideal and Real Gases

A gas which obeys the ideal gas equation, PV = nRT under all conditions of temperature and pressure is called an ‘ideal gas’.However, there is no gas which obeys the ideal gas equation under all conditions of temperature and pressure. Hence, the concept of ideal gas is only theoretical or hypothetical. The gases are found to obey the gas laws fairly well if the pressure is low or the temperature is high. Such gases are, therefore, known as ‘Real gases.’ All gases are real gases. However, it is found that gases which are soluble in water or are easily liquefiable, e. g. CO2, SO2, NH3 etc. show larger deviations than the gases like H2, O2, N2 etc.

Differences between Ideal Gas and Real Gas

Ideal Gases	Real Gases
Ideal Gases obey all gas laws under all conditions of temperature and pressure.	Real Gases obey gas laws only at low pressures and high temperature.
The volume occupied by the molecules is negligible as compared to the total volume occupied by the gas.	The volume occupied by the molecules is not negligible as compared to the total volume of the gas.
The force of attraction among the molecules are negligible.	The force of attraction are not negligible at all temperatures and pressures.
Obeys ideal gas equation PV = nRT	Obey Van der Waals equation (P + an2/V2) (V - nb) = nRT

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