Surface Chemistry - Result Question 29
30. The given graph/data I, II, III and IV represent general trends observed for different physiosorption 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?
(2012)
(I)
(II)
(III)
(IV)
(a) I is physiosorption and II is chemisorption
(b) I is physiosorption and III is chemisorption
(c) IV is chemisorption and II is chemisorption
(d) IV is chemisorption and III is chemisorption
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Answer:
Correct Answer: 30. (a, c)
Solution:
Graph-I represents physiosorption as in physiosorption, absorbents are bonded to adsorbate through weak van der Waals’ force. Increasing temperature increases kinetic energy of adsorbed particles increasing the rate of desorption, hence amount of adsorption decreases.
Graph-II represents chemisorption as it is simple activation energy diagram of a chemical reaction.
Graph-III also represents physical adsorption as extent of adsorption increasing with pressure.
Graph-IV represents chemisorption as it represents the potential energy diagram for the formation of a typical covalent bond.
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