Question

Identify the correct statements about chemisorption:

• I) It is irreversible adsorption
• II) Enthalpy of adsorption is in the range of 20-40 kJ mol\(^-1\)
• III) It is unlayered adsorption
• IV) It does not need appreciable activation energy

• A. I & IV only
• B. I & II only
• C. I & III only
• D. II & III only

Hint:

Chemisorption involves the formation of strong chemical bonds between adsorbent and adsorbate, requiring activation energy, and usually leads to a monolayer adsorption.

Answer 1

The Correct Option is C

- I) It is irreversible adsorption: This is correct. Chemisorption is irreversible because chemical bonds are formed between the adsorbent and adsorbate, making it difficult to reverse the process.
- II) Enthalpy of adsorption is in the range of 20-40 kJ mol\(^-1\): This is incorrect. The enthalpy of chemisorption is usually much higher, often in the range of 40-400 kJ/mol, indicating the formation of stronger bonds.
- III) It is unlayered adsorption: This is correct. Chemisorption typically involves the formation of a monolayer of adsorbate on the surface of the adsorbent.
- IV) It does not need appreciable activation energy: This is incorrect. Chemisorption generally requires activation energy for bond formation between the adsorbate and the adsorbent.
Therefore, the correct answer is (3), which corresponds to statements I and III.