Question

The heat evolved in chemisorption lies in the range of $ (KJ{\text{ mol}}{{\text{e}}^{ - 1}}) $ ?
(A) $ 80 - 240 $
(B) $ 20 - 40 $
(C) $ 40 - 80 $
(D) $ 20 - 100 $

Answer 1

Hint :Chemisorption is the kind of adsorption in which the adsorbate adsorbs at the surface of adsorbent through the formation of chemical bonds. It is an exothermic process and a greater amount of heat is released.

Complete Step By Step Answer:
To solve this question first we need to know about the heat involved in chemisorption and why the enthalpy of chemisorption is high.
Since, the chemisorption occurs by the formation of chemical bonds of the adsorbate on the surface of adsorbent. Thus, very strong bonds are involved in this adsorption process. So, the amount of heat liberated is high.
So, based on our discussion we can say that the amount of heat evolved in chemisorption lies in the range of $ 80 - 240 $ $ (KJ{\text{ mol}}{{\text{e}}^{ - 1}}) $ .
Chemical adsorption is established on the solid surface by substantial sharing of electrons between the adsorbate and adsorbent and results in the formation of strong ionic and covalent bonds. Also, another point to keep in mind is that this chemical adsorption is an irreversible process.
Hence option A is the correct answer.

Note :
Chemisorption is a highly specific process and it is favourable at high pressure and high temperature. Chemisorption techniques are very much effective in day to day life activities like it helps in evaluation the chemical properties of a substance that is of particular use to a chemical reaction. It also tells us about the maximum number of active sites present for the catalytic reaction to take place .