Question

The rate of chemisorption:
A.Decreases with increase of pressure
B.Is independent of pressure
C.Is maximum at one atmospheric pressure
D.Increases with increase in pressure

Answer 1

Chemisorption is a kind of adsorption in which new chemical bonds are generated at the surface of adsorbate and adsorbent. The incident flux is directly proportional to the chemisorption. But, the increasing in pressure will result in the decreasing of incident flux due to low diffusion length of species.

Complete answer:
Adsorption is the phenomenon of accumulation of molecules on the surface of other substances. The surface on which the adsorption is done is called an adsorbent and the substance that is deposited on another surface is known as an adsorbate.
Chemisorption is also a kind of adsorption in which the transfer, sharing of electrons takes place at the contact surface of the adsorbate and adsorbent which results in the new chemical bond formation.
The rate of chemisorption depends on the flux of chemical species. High incident flux results in high chemisorption rate and the increase in pressure results in reduction of incident flux. This is due to the low diffusion length of species. Thus, the increase in pressure results in a low rate of chemisorption.
Thus, the rate of chemisorption decreases with increase in pressure.
The correct answer is Option A.

Note:
The chemisorption not only depended upon the pressure, but also depends upon the various factors like temperature and nature of gas. Corrosion can also be said as an example of chemisorption. An example of adsorption is dipping a piece of chalk in an ink bottle.