Question

Gas masks work on the principle of:
a) Physical adsorption
b) Chemical adsorption
c) Both physical and chemical adsorption
d) none of the above

Answer 1

A gas mask protects us from harmful gases like ${\text{C}}{{\text{O}}_2},{\text{S}}{{\text{O}}_2}{\text{ or C}}{{\text{l}}_2}$ from inhalation, they are made up of filters and one important compound known as activated carbon, also called activated charcoal, which has a dense surface area.

Complete step by step solution:
As mentioned about the dense surface area of activated carbon, it provides a great surface for adsorption to take place, adsorption is a process where adsorbate gets accumulated at the surface and not at its bulk.

Now in a gas mask activated charcoal acts as an adsorbent, due to its huge surface area. Chemicals like ${\text{C}}{{\text{O}}_2},{\text{S}}{{\text{O}}_2}{\text{ or C}}{{\text{l}}_2}$ gets attached to it by weak van der waals force, and this process is known as physical adsorption. Therefore it is evident that the gas mask works on the principle of physical adsorption. But that’s not where the story ends, because of the presence of binding sites many times the activated charcoal creates chemical bonds with foreign particles, and this process is known as chemical adsorption.
Therefore, we can conclude that a gas mask works on the principle of both physical and chemical adsorption.

Hence the correct answer to our question is option (c) i.e., both physical and chemical adsorption.

Note: There are cases in which both physical and chemical adsorption occurs, the extent of physical adsorption is more at low a temperature, therefore when the temperature increases the weak van der waal forces changes to strong chemical bonds, as chemical adsorption is more stable at a higher temperature.