Physical Chemistry - Surface Chemistry

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Q1. Which of the following is NOT a method to increase the adsorption capacity of a solid? (2023)

Solution:

Increasing the temperature generally decreases the adsorption capacity for physisorption, as it can overcome the weak van der Waals forces.

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Q2. What is the term for the maximum amount of adsorbate that can be adsorbed on a given mass of adsorbent? (2020)

Solution:

The maximum amount of adsorbate that can be adsorbed on a given mass of adsorbent is referred to as the adsorption capacity.

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Q3. In the context of surface chemistry, what does the term 'desorption' refer to? (2022)

Solution:

Desorption refers to the process by which an adsorbate is released from the surface of the adsorbent.

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Q4. The term 'adsorption' refers to: (2022)

Solution:

Adsorption is the process where molecules accumulate on the surface of a solid or liquid.

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Q5. In the context of surface chemistry, what does the term 'surface area' refer to? (2020)

Solution:

In surface chemistry, 'surface area' refers to the area available for adsorption, which is crucial for determining the adsorption capacity.

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Q6. Which of the following is a characteristic of multilayer adsorption? (2019)

Solution:

Multilayer adsorption is described by the BET theory, which accounts for the formation of multiple layers of adsorbate on the adsorbent.

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Q7. What type of adsorption is characterized by a low heat of adsorption, typically less than 40 kJ/mol? (2023)

Solution:

Physisorption is characterized by a low heat of adsorption, typically less than 40 kJ/mol, due to weak van der Waals forces.

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Q8. Which of the following is true about the adsorption of gases on solids? (2023)

Solution:

The adsorption of gases on solids is typically an exothermic process, as energy is released when the gas molecules adhere to the surface.

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Q9. What is the primary difference between physisorption and chemisorption? (2023)

Solution:

The primary difference is that chemisorption involves the formation of chemical bonds, while physisorption involves weaker van der Waals forces.

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Q10. What is the term used for the process of removing adsorbed molecules from a surface? (2020)

Solution:

Desorption is the process of removing adsorbed molecules from a surface, while adsorption is the process of molecules adhering to a surface.