Question

Which of the following is not a characteristic of chemisorption ?

• A. Adsorption is specific
• B. Adsorption is irreversible
• C. $\Delta H$ is of the order of 400 kJ
• D. Adsorption may be multimolecular layer

Answer 1

Answer: (D)

Chemisorption (chemical adsorption) has following characteristics:
1. Irreversible
2. Very specific
3. Leads almost to a monolayer adsorption.
4. Generally has heat of adsorption greater than about $20kcal/mol$.
5. May involve activation energy in the adsorption process.
6. Appreciable at high temperatures.
Hence, option (d) is correct as chemical adsorption is always monolayer or unimolecular layer.