The correct option(s) related to adsorption processes is(are)
- Chemisorption results in a unimolecular layer.
- The enthalpy change during physisorption is in the range of 100 to $140\, kJ\, mol ^{-1}$.
- Chemisorption is an endothermic process.
- Lowering the temperature favors physisorption processes.
The Correct Option is A, D
Solution and Explanation
In the context of adsorption processes:
- Option A: "Chemisorption results in a unimolecular layer."
This is correct. Chemisorption typically forms a unimolecular layer on the surface, as each adsorbed molecule forms a chemical bond with the surface. - Option B: "The enthalpy change during physisorption is in the range of 100 to 140 kJ/mol."
This is incorrect. Physisorption involves weaker forces and typically has an enthalpy change in the range of 5 to 40 kJ/mol, not 100 to 140 kJ/mol. - Option C: "Chemisorption is an endothermic process."
This is incorrect. Chemisorption is typically exothermic, meaning it releases energy during the adsorption process, rather than requiring energy. - Option D: "Lowering the temperature favors physisorption processes."
This is correct. Physisorption is favored at lower temperatures because the weak van der Waals forces are more effective at these temperatures.
Final Answer: The correct options are: A and D.
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GMC Azamgarh Admission 2025: Dates, Courses, Fees, Eligibility, SelectJuly 22, 2025Concepts Used:
Surface Chemistry
The study of the chemical phenomena that occur at the interface of two surfaces which can be solid-liquid, solid-gas, solid-vacuum, liquid-gas, etc.
Read Also: Surface Chemistry
Applications of surface chemistry are:
Adsorption:
The process of attraction and aggregation of the molecules of a substance on the surface of a solid is known as adsorption. For Example, N2 adsorbs on the surface of activated charcoal
Two types of adsorption are:-
- Chemisorption: It is also known as Chemical Adsorption.
- Physisorption: It is also known as Physical Adsorption.
Corrosion:
The process through which the refined metals convert themselves into more stable compounds is known as corrosion.
Crystallisation:
The type of technique used in order to purify the substances to separate Solids from liquids is known as crystallisation.
Heterogeneous Catalysis:
The process wherein a catalyst is used in order to increase the rate of a chemical reaction is known as catalysis. The catalyst does not undergo any transformation and can be recovered in a chemically unchanged state.
There are two types of catalysis:-
- When the catalyst involved and the reacting substances are same states of matter or in the same phase, it is known as Homogeneous Catalysis.
- When the catalyst involved and the reacting substances are in different states of matter or different phases, it is known as Heterogeneous Catalysis.