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Comprehension # 1 Many lyophilic sols ...

Comprehension # 1
Many lyophilic sols and few lyophobic sols when coagulated under some special conditions changes into semi rigid mass, enclosing whole amount of liquid within itself, it is called gel and the process is called gelation, Gelatin Agar-agar, gum-Arabic can be converted into gels by cooling them under moderate concentration conditions. Hydrophobic sols like silicic acid. `Al(OH)_(3)` are prepared by double decomposition and exchange of solvent method.
Types of Gel :
(i) Elastic gel : Those gel which have elastic properties.
Ex : Gelatin, Strach, Agar-agar etc.
(ii) Non-elastic gel : Those gel which are rigid.
Ex : Silica gel.
Properties of Gel :
1. Syneresis/weeping of gel : The spontaneous liberation of liquid from a gel is called syneresis or weeping of gels. It is reverse of swelling.
Ex : Gelatin, Agar-Agar show syneresis at low concentration while sillicic acid shows it at high concentration.
2. Imbibition or swelling of gel : When gel is kept in a suitable liquid (water) it absorb large volume of liquid. The phenomenon is called imbibition or swelling of gel.
3. Thixotropic : Some gels when shaken to form a sol, on keeping changes into gel are termed as thixotropic gel and phenomenon is called thixotropy.
Ex : Gelatin and silica liquify on shaking changing into corresponding sol and sol on keeping changes back into gel.
Which of the following is used to adsorb water ?

A

Silica gel

B

Calcium acetate

C

Hair gel

D

Cheese

Text Solution

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The correct Answer is:
A
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Comprehension # 1 Many lyophilic sols and few lyophobic sols when coagulated under some special conditions changes into semi rigid mass, enclosing whole amount of liquid within itself, it is called gel and the process is called gelation, Gelatin Agar-agar, gum-Arabic can be converted into gels by cooling them under moderate concentration conditions. Hydrophobic sols like silicic acid. Al(OH)_(3) are prepared by double decomposition and exchange of solvent method. Types of Gel : (i) Elastic gel : Those gel which have elastic properties. Ex : Gelatin, Strach, Agar-agar etc. (ii) Non-elastic gel : Those gel which are rigid. Ex : Silica gel. Properties of Gel : 1. Syneresis/weeping of gel : The spontaneous liberation of liquid from a gel is called syneresis or weeping of gels. It is reverse of swelling. Ex : Gelatin, Agar-Agar show syneresis at low concentration while sillicic acid shows it at high concentration. 2. Imbibition or swelling of gel : When gel is kept in a suitable liquid (water) it absorb large volume of liquid. The phenomenon is called imbibition or swelling of gel. 3. Thixotropic : Some gels when shaken to form a sol, on keeping changes into gel are termed as thixotropic gel and phenomenon is called thixotropy. Ex : Gelatin and silica liquify on shaking changing into corresponding sol and sol on keeping changes back into gel. The process of imbibing water when elastic gel are placed in water is called :

Many lyophilic sols and few lyophobic sols when coagulated under some special conditions changes into semi rigid mass, enclosing whole amount of liquid within of liquid within itself, it is called gel and the process is called gelation. Gelatin, agar-agar, gum-Arabic can be converted into gels by cooling them under moderate concentration conditions. Hydrophobic sols like silicic acid. Al(OH)_(3) are prepared by double decomposition and exchanged of solvent method. Types of gel : 1. Syneresis/weeping of gel : The spontaneous liberation of liquid from a gel is called syneresis or weeping of gels. It is reverse of swelling. e.g., geletin, agar-agar show syneresis at low concentration while silicic shows it at high concentration. 2. Imbibition or swelling of gel : When gel is kept in a suitable liquid (water) it absorb large volume of liquid. The phenomenon is called imbibition or sweeling of gel. 3. Thixotropic : Some gels when shaken to form a sol, on keeping changes into gel are termed as thixotropic gel and phenomenon is called thixotropy. e.g., gelatin and silica liquify on shaking changing into corresponding sol and the sol on keeping changes back into gel. Some types of gels like gelatin and silica liquify on shaking thereby changing into sols. The sols on standing change back into gels. This process is know as :

Lyophilic sols are :

Lyophobic sols are:

Lyophilic sols are:

Lyophilic sols are more stable than lyophobic sols because

What happens when lyophilic sol is added to a lyophobic sol?

Which of the following sols is hydrophobic ?

Distinguish between lyophilic and lyophobic sols.

Which of the following is correct about lyophilic sols?