Question

What is meant by an ideal gas and a real gas? What are the causes of the deviation from ideal gas behavior? Plot a graph between pressure and volume for ideal gases and real gases.

Answer 1

Hint:If we know whether the gas is ideal or real, we can predict the behavior of their intermolecular attractive forces, and the volume occupied by those gases within a system. An Ideal gas, as the names go behaves ideally, under any given temperature and pressure.

Complete answer:
What is an ideal gas?
An ideal gas will follow all the gas laws (i.e., Boyle’s law, Charles’s law, and Avogadro’s law), under a very wide range of temperature and pressure. Ideal gas also follows the kinetic theory of gases which states, there will be negligible amount of volume occupied (\[ \approx \]0) by each gas molecule and that there would be no attractive forces between the gas molecules. Both of the statements are incorrect and hence we have the concept of real gases.

What is a real gas?
A real opposite does not follow the gas law under a wide range of temperature and pressure, and it also disobeys the kinetic gas equation. Eg., if we compress a real gas, the pressure will increase between the gas molecules, which will result in the dominance of attractive forces, and the gas will convert into liquid (condensation), which is contradictory to the “no attractive forces” statement by the kinetic theory of gases.
There are two conditions under which a real gas deviates from the ideal gas behavior these are;
1. Low temperature
2. High pressure
The graph of a real and ideal gas is drawn below, at a constant temperature.

Point ‘A’ in the graph shows the intersection, where the real gas can show ideal behavior.

Note:
The concept of real gas is hypothetical means there is no such gas which can show ideal behaviors under a wide range of temperature and pressure. However, a real gas can show ideal behavior for a shorter range of temperature and pressure, meaning at low pressure and high temperature a real gas can show ideal behavior.