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प्रश्न
Distinguish between the meaning of the terms adsorption and absorption. Give one example of.
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.
What is the effect of temperature on chemisorption ?
Why is adsorption always exothermic?
Why are powdered substances more effective adsorbents than their crystalline forms?
Give reason why a finely divided substance is more effective as an adsorbent.
What are the factors which influence the adsorption of a gas on a solid?
Discuss the effect of pressure and temperature on the adsorption of gases on solids.
Write one similarity between Physisorption and Chemisorption
Physisorption is reversible while chemisorption is irreversible. Why ?
Give reasons for the following observations :
Powdered substances are more effective adsorbents.
Answer in one sentence:
Name type of adsorption in which vander Waals focres are present.
Which of the following compounds is formed when tungsten adsorbs oxygen gas?
Which of the following is an example of physisorption?
Adsorption increases when ____________.
Which among the following is a property of physisorption?
Powdered substances are more effective adsorbents than their crystalline forms because ____________.
Which among the following is true for chemisorption?
In physisorption, adsorption is generally ____________.
Chromatography is based on the principle of ____________.
The extent of adsorption increases with the ____________.
Extent of physisorption of a gas increases with ______.
Which of the following is not a favourable condition for physical adsorption?
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 it important to have clean surface in surface studies?
What is the role of activated charcoal in gas mask used in coal mines?
What is the role of diffusion in heterogenous catalysis?
What is the role of adsorption in heterogenous catalysis?
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:-
Chromatography is based on:-
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?
