Question

(b) If the gas like O₂, H₂, CO, Cl₂, NH₃ or SO₂ is taken in a closed vessel containing powdered charcoal it is observed that the pressure of the gas in the enclosed vessel decreases. The gas molecules concentrate at the surface of charcoal i.e., gases are adsorbed at the surface. This phenomena is called adsorption.

Answer 1

Dear Student,

Pressure of the container is due to the collision of the molecules of gas with each other and with with the wall of the containers. In presence of powdered charcoal, adsorption of these gases occur on the surface of the charcoal which decreases their movement and thus, decreases the collision of molecules leading to decrease in the pressure of the container.
Here we are talking about the pressure by the gases, adsorption is directly proportional to the pressure applied on the gases. When pressure is applied on the gas,i.e. pressure on the gas increases the molecules comes more closer to the surface of the adsorbent and thus rate of adsorption increases.