Question

The given graph/data I, II, III and IV represent general trends observed for different physisorption and chemisorption processes under mild conditions of temperature and pressure. Which of the following choice(s) about I, II, III and IV is (are) correct?

• A. I is physisorption and II is chemisorption
• B. I is physisorption and III is chemisorption
• C. IV is chemisorption and II is chemisorption
• D. IV is chemisorption and III is chemisorption

Answer 1

Answer: (A), (C)

IV is chemisorption and II is chemisorption

Graph - I represents physisorption as in physisorption, absorbents are bonded to absorbate through weak van der Waals' force.
Increasing temperature increases kinetic energy of absorbed particles increasing the rate of desorption, hence amount of absorption decreases.

Graph - III also represents physical absorption as extent of absorption increasing with pressure.

Graph - II represents chemisorption as it is simple activation energy diagram of a chemical reaction.

Graph - IV represents chemisorption as it represents the potential energy diagram for the formation of a typical covalent bond.