Question

1. Distinguish between real gas and ideal gas. 

2. Explain the deviation of the following gases from ideal behaviouron the basis of the pV vs. p plot. CO, CH₄ , H₂ and He.

Answer 1

1. Real gas do not follow, Boyle’s law, Charles law, and Avagadro law perfectly under all conditions. Ideal gas follow,

Boyle’s law, Charles’ Law and Avagadro law strictly under all conditions. 

2.

It can be seen that at constant temperature pV vs p plots for these gases are not straight lines. Two types of curves are seen. 

In the curves for H₂ and He, as the pressure increases the value of pV also increases. These gases show positive deviation from ideal behaviour at all pressures. The second type of plot is seen in the case of CO and CH₄. For these gases the pV value decreases with increase in pressure and reaches to a minimum value characteristics of the gas. After that PV value starts increasing. The curve then crosses the line for ideal gas and after that shows positive deviation continuously.