Question

In Freundlich Adsorption isotherm, the value of $\dfrac{1}{n}$ is:
A. 1 in case of physical adsorption
B. 1 in chemisorption
C. Between 0 and 1 in all cases
D. Between 2 and 4 in all cases

Answer 1

Hint: Adsorption is defined as a surface phenomenon where the particles are attached with the top most layer of material and in this case molecules, atoms or an ions of a gas, liquid or a solid present in a dissolved state which are attached with the surface.

Complete step-by-step answer: Adsorption is a process which involves the accumulation of a substance in molecular species in higher concentration on the surface. In the process of adsorption two components are required: adsorbate substance which is deposited and adsorbent substance on which it is absorbed.
Freundlich Adsorption isotherm gives us empirical relation between the quantity of gas adsorbed into the solid surface and pressure exerted by gas. This equation was given in 1909 by the scientist Herbert Freundlich in which the expression represents the isothermal variation of adsorption of quantity of gas adsorbed by unit mass of solid adsorbent with gas pressure.
Mathematical expression for Freundlich Adsorption isotherm is as shown:
$\dfrac{x}{m}=K{{p}^{\dfrac{1}{n}}}$
Here x is mass of adsorbate, m is mass of adsorbent, p is equilibrium pressure, K and n are constants and the value of n is always between 0 and 1 in all cases.

Thus option C is the correct answer.

Note:There are basically two types of adsorption physical and chemical adsorption. Physical adsorption is due to weak van der waal forces between adsorbate and adsorbent whereas chemical adsorption is due to strong chemical forces of bonding between adsorbate and adsorbent.