Question

The given graphs/data $I,II,III$ and $IV$ represent general trends observed for different physisorption and chemisorption processes under mild conditioning of temperature and pressure. Which of the following choices 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-$I$ Represent physisorption as in physisorption, absorbents are bonded to adsorbate through weak van der Waal's force. Increasing temperature increases kinetic energy of adsorbed particles, increasing the rate of desorption, hence amount of adsorption decreases.
Graph -$III$ also represent physical adsorption as extent of adsorption increasing with pressure.
Graph -$II$ represesnts 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 formaion of a typical covalent bond.