Question

Question 5.4:

What are the factors which influence the adsorption of a gas on a solid?

Answer:

There are various factors that affect the rate of adsorption of a gas on a solid surface.

(1) Nature of the gas:

Easily liquefiable gases such as NH₃, HCl etc. are adsorbed to a great extent in comparison to gases such as H₂, O₂etc. This is because Van der Waals forces are stronger in easily liquefiable gases.

How is the Van Der Waal's forces stronger in easily liquefiable gases?

Answer 1

Here in the above case, The vander wall forces are stronger in easily liquefiable gases.
This can be understood as follows:
The major difference between the gas and liquid is the intermolecular force of attraction.
If the intermolecular forces between the gases are more then the gas can be liquify easily just by cooling it or by increasing the external pressure on the gas.
The intermolecular forces basically depends upon the type of interaction between the molecules, generally we consider vander wall forces in case of gases. The magnitude of vander waal forces depend on mass of the gas and its surface area.
Higher is the mass, higher will be the surface area and hence higher will be the magnitude of intermolecular forces.
Therefore, HCl and H₂O are easily liquefiable gases due to larger magnitude of vander waal forces as compare to O₂ and H₂.