Question

The heat of physisorption lie in the range of:
A. $1$ to $10kJmo{l^{ - 1}}$
B. $20$ to $40kJmo{l^{ - 1}}$
C. $40$ to $200kJmo{l^{ - 1}}$
D.$200$ to $400kJmo{l^{ - 1}}$

Answer 1

We know that adsorption is the process in which the molecules species are deposited onto the surface . There are two types of adsorption , they are physisorption and chemisorption. Physisorption is formed due to van der Waals forces and chemisorption is formed due to chemical forces.

Complete step by step answer:
As we know that physisorption is formed due to van der Waals forces , they are not specific in nature. But chemisorption is specific in nature. Physisorption is reversible in nature but chemisorption is non reversible in nature. The heat of physisorption is lower than chemisorption. It is because of the reason that in physisorption there is no chemical reaction. The heat of physisorption lie in the range of $20$ to $40kJmo{l^{ - 1}}$ and the heat of chemisorption lie in the range of $80$ to $240kJmo{l^{ - 1}}$. So from the above explanation it is clear to us that the correct answer of the given question is option : B. $20$ to $40kJmo{l^{ - 1}}$.
Therefore, only option B is correct.

Additional information: It is very important to know the fact that physisorption prefers low temperature but chemisorption prefers higher temperature. The activation energy is lower in physisorption but the activation energy is higher in chemisorption. Physisorption is multimolecular in nature but chemisorption is unimolecular in nature.

Note: Always remember that the heat of reaction is lower in physisorption as compared to heat of reaction of chemisorption. This is because there is no chemical reaction occurring in physisorption. In chemisorption chemical reactions occur. . The heat of physisorption lie in the range of $20$ to $40kJmo{l^{ - 1}}$ and the heat of chemisorption lie in the range of $80$ to $240kJmo{l^{ - 1}}$.