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
(A) The initial assertion is accurate since chemisorption yields a monomolecular layer, while physisorption leads to a multimolecular layer.
(B) The subsequent claim is inaccurate because the enthalpy shift in physisorption typically falls within the range of (20 – 40) kJ mol–1.
(C) Chemisorption demonstrates an exothermic characteristic, with an enthalpy of adsorption ranging from (80 – 240) kJ mol–1.
(D) A reduction in temperature prompts an augmentation in the degree of physisorption.
Consequently, statements (A) and (D) are correct.
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Concepts 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.
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