Depending upon the solvent affinity, the colloids are classified into two categories.
- Lyophobic Colloids or Sols
- Lyophilic Colloids or Sols
Lyophobic Colloids or Sols: Lyophobic colloids are those colloids that have no spontaneous tendency to pass into the colloidal state and are obtained with difficulty. Lyophobic Colloid or Sols are also called hydrophilic when the dispersion medium is water.
For example, metal sulfides, silver halides, egg, silicic acid, ferric hydroxide etc., form Lyophobic colloids with water medium.
Lyophilic Colloids or Sols: Lyophilic colloids are those colloids that are quite easily formed by the spontaneous dispersion of a substance in the dispersion medium. The Lyophilic Colloids are also called hydrophilic when the dispersion medium is water.
For Example, protein, starch, glue, etc. form Lyophilic Colloids with water.
Let’s take a look at below for the difference between Lyophobic and Lyophilic colloids.
Difference Between Lyophobic and Lyophilic Colloids
|Lyophilic Colloid or Sols||Lyophobic Colloid or Sols|
|Lyophilic colloids pass into the colloidal form readily when brought in contact with the solvent.||Lyophobic colloids do not form the colloidal solutions easily when treated with solvent.|
|They are called reversible sols because they can be recovered from the colloidal solutions and converted into the colloidal form when desired.||They are called irreversible sols because they cannot be recovered from their colloidal form.|
|Small quantities of electrolytes do not affect precipitation, but only large quantities of electrolytes cause precipitation.||Even small quantities of the electrolytes can cause precipitation.|
|The particles are not easily detected in the ultra-microscope.||The particles are easily detected by an ultra an ultra-microscope.|
|The particles may or may not migrate in an electric field. The migration may be in ay direction.||Particles migrate only in one direction in the presence of an electric field.|
|Lyophilic sols have very high viscosities and can be prepared at high concentrations.||Lyophobic sols have viscosity almost equal to that of the dispersion medium. These sols can be obtained in small concentrations.|
|Substances like starch, protein, gums, soaps are common examples of lyophilic colloid.||Colloids of metals (Au, Pt), sulphur, arsenious sulphide and silver iodide are common examples of lyophobic sols.|
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