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प्रश्न
Distinguish between the meaning of the terms adsorption and absorption. Give one example of.
Distinguish between the meaning of the terms adsorption and absorption.
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उत्तर १
Adsorption is a surface phenomenon of accumulation of molecules of a substance at the surface rather than in the bulk of a solid or liquid. The substance that gets adsorbed is called the ‘adsorbate’ and the substance on whose surface the adsorption takes place is called the ‘adsorbent’. Here, the concentration of the adsorbate on the surface of the adsorbent increases. In adsorption, the substance gets concentrated at the surface only. It does not penetrate through the surface to the bulk of the solid or liquid. For example, when we dip a chalk stick into an ink solution, only its surface becomes coloured. If we break the chalk stick, it will be found to be white from inside.
On the other hand, the process of absorption is a bulk phenomenon. In absorption, the substance gets uniformly distributed throughout the bulk of the solid or liquid.
उत्तर २
| No. | Adsorption | Absorption |
| 1. | Adsorption is a surface phenomenon as the adsorbed matter is concentrated only at the surface and does not penetrate through the surface to the bulk of adsorbent. | Absorption is a bulk phenomenon as the absorbed matter is uniformly distributed inside as well as at the surface of the bulk of a substance. |
| 2. | The concentration of the adsorbate is high only at the surface of the adsorbent. | The concentration of the absorbate is uniform throughout the bulk of the absorbent. |
| 3. | It is dependent on temperature and pressure. | It is independent of temperature and pressure. |
| 4. | It is accompanied by the evolution of heat known as the heat of adsorption. | It may or may not be accompanied by evolution or absorption of heat. |
| 5. | It depends on the surface area. | It is independent of surface area. |
| 6. | Adsorption of a gas or liquid-like acetic acid by activated charcoal. | Absorption of water by cotton, absorption of ink by blotting paper. |
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संबंधित प्रश्न
Write the differences between physisorption and chemisorption with respect to the following:
(i) Specificity
(ii) Temperature dependence
(iii) Reversibility and
(iv) Enthalpy change
Give reasons for the following observations:
Physisorption decreases with increase in temperature.
Differentiate between adsorbtion and absorption.
Why is adsorption always exothermic?
Write any two characteristics of chemisorption.
What is the difference between physisorption and chemisorption?
What are the factors which influence the adsorption of a gas on a solid?
Give reasons for the following observations :
Powdered substances are more effective adsorbents.
How does chemisorption vary with temperature?
Answer in one sentence:
Name type of adsorption in which vander Waals focres are present.
Answer in one sentence:
Name type of adsorption in which the compound is formed.
Which among the following is a property of physisorption?
Which among the following is true for chemisorption?
Chromatography is based on the principle of ____________.
The extent of adsorption increases with the ____________.
The physical adsorption is due to ____________.
Physical adsorption of a gaseous species may change to chemical adsorption with ______.
In physisorption adsorbent does not show specificity for any particular gas because ______.
In which of the following reactions heterogenous catalysis is involved?
(a) \[\ce{2SO2 (g) + O2 (g) ->[NO(g)] 2SO3 (g)}\]
(b) \[\ce{2SO2 (g) ->[Pt(s)] 2SO3 (g)}\]
(c) \[\ce{N2 (g) + 3H2 (g) ->[Fe(s)] 2NH3 (g)}\]
(d) \[\ce{CH3COOCH3 (l) + H2O (l) ->[HCI(l)] CH3COOH (aq) + CH3OH (aq)}\]
Why is chemisorption referred to as activated adsorption?
Why do physisorption and chemisorption behave differently with rise in temperature?
What is the role of activated charcoal in gas mask used in coal mines?
Give an example where physisorption changes to chemisorption with rise in temperature. Explain the reason for change.
Assertion: Detergents with low CMC are more economical to use.
Reason: Cleansing action of detergents involves the formation of micelles. These are formed when the concentration of detergents becomes equal to CMC.
What is the role of adsorption in heterogenous catalysis?
Which among the following is a false statement?
In physical adsorption, gas molecules are bound on the solid surface by
A plot of 10 g (x/m) versus 10 g p for the adsorption of a gas on the surface of a solid gives a straight line with slope equal to:-
Rate of physisorption increase with:-
Chromatography is based on:-
Adsorption play no role in:-
Write three differences between physisorption and chemisorption.
Assertion A : Activated charcoal adsorbs SO2 more efficiently than CH4.
Reason R : Gases with lower critical temperatures are readily adsorbed by activated charcoal.
In light of the above statements, choose the correct answer from the options given below.
Which of the following statements is incorrect regarding physisorptions?
