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)

Adsorption may be multimolecular layer

Answer 2

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 $20\, kcal/mol$. 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.