Ideal & Real Gases

A gas which obeys Boyle’s Law & Charle’s Law under all conditions of temperature and pressure is known as an Ideal Gas or Perfect Gas.

Since the gas equation (PV = nRT) is obtained by combining Boyle’s Law and Charle’s Law, therefore, an Ideal may also be defined as fallows;

A gas which obeys the gas equation (PV = nRT) under all conditions of temperature and pressure is called an Ideal Gas.

However, it is observed that there is no gas which obeys the gas equation under all conditions of temperature and pressure. Hence concept of Ideal gas is only theoretical or hypothetical. Such gases which do not obey gas equation under all conditions of temperature and pressure are known as Real Gases. These gases are found to obey gas laws fairly well if pressure is low and temperature is high.

All gases are real gases. They show more and more deviations from the gas laws as pressure is increased and temperature is lowered.