### Applications of adsorption - class-XII

 Description: applications of adsorption Number of Questions: 26 Created by: Neema Pandya Tags: surface chemistry chemistry adsorption and colloids
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Which of the following is most favourable for vander waals  adsorption?

1. high pressure and high temperature

2. low pressure and low temperature

3. low pressure and high temperature

4. high pressure and low temperature

Correct Option: D
Explanation:

Physisorption is Vanderwaals adsorption, it occurs at high pressure and low temperature conditions.

Adsorption column chromatography has been used for :

1. isolation and purification of vitamins and hormones

2. examination of vegetable oil and pharmaceutical preparations

3. used as indicator

4. all of the above

Correct Option: A,B
Explanation:

Column chromatography is used for isolation and purification of vitamins and hormones and for the examination of vegetable oil and pharmaceutical preparations.

Application of adsorption chromatography is/are _________.

1. separation of relatively non polar, water insoluble compounds

2. seperation of isomers

3. purification of antibody fragments

4. all of the above

Correct Option: D
Explanation:

Adsorption chromatography has many applications. Generally, it is used for determining the concentration of a compound (or its purity), separating out a mixture into individual componentsseperation of isomers, and identifying what is in a mixture and seperate on the basis of solubility also. There are three main types of adsorption chromatography - column, thin layer, and gas-solid.

The ion exchange resins helps in:

1. Removing moisture

2. Controlling humidity

3. Removing hardness of water

4. All of the above

Correct Option: C
Explanation:

Ion exchange resin method is used for removing hardness of water.

Application of adsorption in food industry is/are :

1. decolourisation of edible oils

2. to remove bitter substances from fruit juices

3. to remove salt from water

4. to remove sugar contents

Correct Option: A,B
Explanation:

Decolorization of edible oils and removing bitter substances can be obtained through adsorption.

Application of adsorption in pharmacy and allied field is/are :

1. Decolourising agents

3. Purified talc

4. None of the above

Correct Option: A,B
Explanation:

Application of adsorption in pharmacy and allied fields are Decolourising agents, adsorption chromatography.

Activated charcoal is used in gas masks to remove poisonous gases.

1. True

2. False

Correct Option: A
Explanation:

1. For desiccation or dehumidification

2. Heterogeneous catalysts

3. For both heterogenous catalysts and for desiccation or dehumidification

4. None of the above

Correct Option: C
Explanation:

1.Charcoal is used as a decoloriser as it adsorbs the coloring matter from the coloured solution of sugar.

2. Silica gel adsorbs moisture from the desiccators.

3. Silica and alumina gels are used as adsorbents for removing moisture and for controlling humidity of rooms.

4. Activated charcoal is used in gas masks as it adsorbs all the toxic gases and vapours and purifies the air for breathing.

5 .Adsorption processes are useful in carrying out heterogeneous catalysis.

Which of the following can adsorb largest volume of hydrogen gas?

1. Finely divided platinum

2. Finely divided nickel

4. Colloidal Hydroxide

Correct Option: C
Explanation:

Colloidal solution of palladium can adsorb largest volume of hydrogen gas as the surface area of palladium is maximum in its colloidal solution. Higher is the surface area of catalyst, larger will be the volume of hydrogen adsorbed.

Which of the following is/are true statement(s)?

1. Water vapour is absorbed by anhydrous calcium chloride while it is adsorbed by silica gel.

2. $NH _3$ is absorbed by water but adsorbed by charcoal.

3. Sugar is decolourized by animal charcoal based on adsorption.

4. Water is absorbed by conc. $H _2SO _4$.

Correct Option: A,B,C,D
Explanation:

Adsorption is the adhesion of atoms, ions, or molecules from a gas, liquid, or dissolved solid to a surface. This process creates a film of the adsorbate on the surface of the adsorbent.
Absorption is a physical or chemical phenomenon or a process in which atoms, molecules or ions enter some bulk phase – gas, liquid or solid material.

a) Water vapour is absorbed by anhydrous calcium chloride while it is adsorbed by silica gel.
b) Ammonia i
s absorbed by water but adsorbed by charcoal.
c) Decolourisation of sugar solution by activated charcoal is another example of adsorption. Charcoal absorbs the colouring material and thus decolourising the solution.
d) Water is absorbed by sulphuric acid because both are in same phase.
NHis absorbed by water but adsorbed by charcoal.

Which of the following gases is adsorbed most by activated charcoal?

1. $CO _2$

2. $N _2$

3. $CH _4$

4. $H _2$

Correct Option: A
Explanation:

Easily liquefiable gases can adsorb more than the other gases.

As $CO _2$ is an easily liquefiable gas, hence it is adsorbed more by charcoal.

Silical gel is commonly used as:

1. wetting agent

2. drying agent

3. solvent

4. catalyst

Correct Option: B
Explanation:

Silica gel is commonly used as a drying agent as it adsorb moisture on its surface to prevent growth of microorganism and foul smelling.

For purification of tincture of alkaloids from pigments before determination of their alkaloidal content, adsorption column chromatography has been used for separation and purification of the Alkaloids of Atropa Belladonna from the bulk of non- alkaloidal matter present in alumina columns.

1. True

2. False

Correct Option: A
Explanation:

Adsorption Chromatography with alumina as the adsorbent may be used for the separation and purification of the Alkaloids of Atropa Belladonna from the bulk of non- alkaloidal matter present in alumina columns, whereas tincture prepared by the percolation process in adsorption column chromatography.

Dyes like cosin and fluorescein are used as indicator in titrating bromide solution with $ZnSO _4$

1. True

2. False

Correct Option: A
Explanation:

True dyes like cosin and fluorescein are used as indicator in titrating bromibe solution with zinc sulphate.

All heterogeneous catalysts are based on the process of adsorption

1. True

2. False

Correct Option: A
Explanation:

Heterogeneous catalysts are materials capable of adsorbing liquids and gasses on their surface. Hence, they are based on the process of adsorption.

Animal charcoal is used to remove moisture

1. True

2. False

Correct Option: B
Explanation:

Animal charcoal is known for its power to remove substance from solution. It is chiefly known for its decolourising property and widely used in the industry as a decolourising agent.

Most strongly adsorb component forms lower most band while least adsorb component forms top most band on adsorbent media

1. True

2. False

Correct Option: B
Explanation:

Most strongly adsorbed component forms the topmost band while  the least adsorbed component forms the lower most band on adsorbent media.

Removal of chlorine from drinking water in the food industry is done by adsorption :

1. True

2. False

Correct Option: A
Explanation:

Activated carbon filtration is a commonly used technology based on the adsorption of contaminants onto the surface of a filter. This method is effective in removing certain organics (such as unwanted taste and odours, micropollutants), chlorine, fluorine or radon from drinking water or wastewater.

In  physical adsorption Zeolite(A/B)'s  applications are  seperation of n-paraffins and i paraffins etc.

1. True

2. False

Correct Option: A
Explanation:

There are several commercial applications based on this mechanism in adsorptive separation processes. One typical example is separating normal paraffin from iso-paraffin and aromatics in an adsorption process using zeolite 5A as an adsorbent.

State one method by which carbon dioxide is removed from the air?

1. Absorption method

2. Distillation method

4. None of these

Correct Option: C
Explanation:
Activated carbon can be used as a $CO _2$ scrubber. Air with high $CO _2$ content mere blew over activated carbon bed and get absorbed.

Which of the following is used to adsorb water?

1. Silica gel

2. Calcium acetate

3. Hair gel

4. Cheese

Correct Option: A
Explanation:

Silica gel has a very strong affinity for water and will adsorb it in preference to most other substances. It is also a good adsorbent for HCl, gasoline-range hydrocarbons, sulphur and nitrogen compounds, aromatics and many others. Silica Gel is in wide use in many industries for a myriad number of applications where a high capacity desiccant or selective adsorbent is required.

Which of the following is/are application(s) of adsorption?

1. De-ionization of water

3. Hygroscopic nature of $CaCl _2$

4. Heterogeneous catalysis

Correct Option: A,B,D
Explanation:
The phenomenon of attracting and retaining the molecules of a substance on the surface of a liquid or a solid resulting into a higher concentration of the molecules on the surface is called adsorption. As a result of adsorption, there is a decrease of surface energy. The process of removal of an adsorbed substance from the surface on which it is adsorbed is called desorption. It is the reverse of adsorption and can be brought about by heating or by reducing the pressure.

Adsorption finds extensive applications both in research laboratory and in industry. A few applications are discussed below:
All gas masks are devices containing suitable adsorbent so that the poisonous gases present in the atmosphere are preferentially adsorbed and the air for breathing is purified.
In heterogeneous catalysis:
The action of certain solids as catalysts is best explained in terms of adsorption. The theory is called adsorption theory. According to this theory, the gaseous reactants are adsorbed on the surface of the solid catalyst. As a result, the concentration of the reactants increases on the surface and hence, the rate of reaction increases. The theory is also able to explain the greater efficiency of the catalyst in the finely divided state, the action of catalyst promoters and poisons.
In softening of hard water (De-ionization of water):
The use of ion exchangers for softening of hard water is based upon the principle of competing adsorption just as in chromatography. Hygroscopic nature of $CaCl _2$ is not related to adsorption.

Which of the following increase(s) the activation of a solid adsorbent?

1. Polishing the surface of the solid adsorbent.

3. Blowing superheated steam through the porous adsorbent.

4. Adsorption at very low pressure.

Correct Option: B,C
Explanation:

Adsorption is the adhesion of atoms, ions or molecules from a gas, liquid, or dissolved solid to a surface.
Adsorption of gases on solids depends on the following factors:

1) Surface area of the adsorbent: Adsorption is surface phenomenon. The extent of adsorption is directly proportional to the surface area of adsorbent. Finely divided metals and porous solids like charcoal, silica gel etc. posses more surface area when compared with solid lumps.

2) Effect of pressure: Extent of adsorption increases with an increase in equilibrium pressure.

3) Nature of the gas: Since physical adsorption is non-specific, every gas gets adsorbed on the surface of any solid. Under a given conditions of temperature and pressure, the easily liquefiable gases such as $NH _3, HCl$ and $SO _2$ are adsorbed more than the gases like $H _2, N _2$ and $CO$. The ease with which a gas can be liquefied is determined by its critical temperature, $T _c$.

Polishing the surface of the solid adsorbent makes no effect on adsorption.

Lake test of $Al^{3+}$ ion is based on adsorption of blue litmus on solid surface of :

1. $Al$

2. $Al(OH) _3$

3. $Al _2O _3$

4. $AlCl _3$

Correct Option: B
Explanation:

Lake test of $Al^{3+}$ ion is based on adsorption of blue litmus on solid surface of $Al(OH) _3$. The dye aluminon is adsorbed by the gelatinous $Al(OH) _3$ precipitate to form lake coloured solution. This test is used as a confirmatory test for $Al^{3+}$ after precipitation of $Al(OH) _3$ with aqueous ammonia.

Which is not correct regarding the adsorption of a gas on surface of a solid?

1. On increasing temp. adsorption increase continuously

2. Enthalpy & entropy change is Ve

3. Adsorption is more for some specific substance

4. Reversible

Correct Option: A
Explanation:
Adsorption of gas $\propto$ $\dfrac{1}{temperature}.$
Thus, as the temperature of the gas increases, the gas molecule gets energy and leave the surface. Thus, the rate of adsorption decreases with increase in temperature.

What is the role of adsorption in froth floatation process used especially for concentration of sulphide ores?

1. Shape selective catalysts

2. Adsorption of pine oil on sulphide ore particles

3. Adsorption of pine oil on impurities

4. Production of heat in the process of exothermic reaction

Correct Option: B
Explanation:
• In Froth floatation process a low-grade sulphide ore is concentrated by separating it from silica and other earthy matter by this method using pine oil and frothing agent.
• Pine oil is adsorbed on sulphide ore particles so as to facilitate the further process.
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