Q1. 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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Q2. 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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Q3. 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.
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Q4. What is the significance of the Langmuir isotherm in surface chemistry? (2023)
Solution:
The Langmuir isotherm assumes a fixed number of adsorption sites and describes monolayer adsorption on a surface.
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Q5. In the context of adsorption, what does the term 'selectivity' refer to? (2022)
Solution:
Selectivity in adsorption refers to the preference of an adsorbent for one gas over another, which can be crucial in separation processes.
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Q6. Which of the following statements about chemisorption is true? (2022)
Solution:
Chemisorption involves the formation of strong chemical bonds between the adsorbate and the surface, making it generally irreversible.
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Q7. Which of the following is NOT a method for measuring surface area of adsorbents? (2022)
Solution:
Thermogravimetric analysis (TGA) is not a method for measuring surface area; it is used to study thermal stability and composition.
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Q8. The Freundlich adsorption isotherm is best described by which equation? (2023)
Solution:
The Freundlich isotherm is represented by the equation x/m = kP^(1/n), where x is the amount adsorbed, m is the mass of the adsorbent, and P is the pressure.
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Q9. 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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Q10. 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.
