The correct answer is (2) A and C only.
The characteristics of chemisorption in more detail:
(A) Highly specific in nature:
Chemisorption is highly specific because it involves strong chemical bonds forming between the adsorbate (the substance being adsorbed) and the adsorbent (the surface on which adsorption occurs). These chemical bonds are often covalent or ionic in nature. Because of this specificity, chemisorption tends to be selective, meaning it occurs with certain molecules or atoms that have the right chemical properties to form bonds with the adsorbent surface. This selectivity makes chemisorption distinct from physisorption, which is typically non-specific and involves weaker van der Waals forces or London dispersion forces.
(C) High heat of adsorption:
Chemisorption is characterized by a high heat of adsorption, which means that energy is either released or absorbed during the process. When chemical bonds are formed between the adsorbate and the adsorbent, energy is often released in the form of heat. This release of energy results in a high heat of adsorption. In contrast, physisorption typically involves weaker forces and does not release or absorb as much heat during the adsorption process.
Now, let's address the characteristics that do not apply to chemisorption:
(B) Low activation energy:
Chemisorption usually involves a higher activation energy compared to physisorption. Activation energy is the energy required for a reaction to occur. In chemisorption, because strong chemical bonds are forming or breaking, a significant amount of energy is needed to initiate the process. This is in contrast to physisorption, where weaker forces require lower activation energy.
(D) Reversible in nature:
Chemisorption is often not reversible under normal conditions. This lack of reversibility is due to the formation of strong chemical bonds, which are relatively stable. Breaking these bonds typically requires a significant amount of energy, and under normal conditions, chemisorption is considered irreversible. In contrast, physisorption is typically reversible because it involves weaker forces (van der Waals forces) that can be easily disrupted with changes in temperature or pressure.
In summary, chemisorption is characterized by its specificity, involving strong chemical bonds and a high heat of adsorption. These characteristics distinguish it from physisorption, which is typically non-specific, involves weaker forces, and is often reversible. |
