Colloidal Dispersion
Dispersion System:-
A Dispersion system is defined as a system in which dispersed phase is distributed uniformly through out dispersion medium.
Classification of Dispersion system
S.N. Dispersion medium Dispersed phase Example
1. Gas Liquid fog
2. Gas Solid Smoke
3. Liquid Gas Foam(aerosol)
4. Liquid Liquid Colloidal gold in water
5. Liquid Solid Oil globules or water globules
6. Solid Gas Solid foam
7. Solid Liquid Mineral oil in wax
8. Solid Solid Colloidal gold in glass
Colloidal Dispersion :-
A Dispersion system in which dispersed phase size range 1nm - 1um is distributed uniformly through out the dispersion medium are called as colloidal dispersion.
Classification of colloidal dispersion
Colloidal dispersion are classified into following types-
1. Lyophilic Colloidal
2. Lyophobic Colloidal
3. Association Colloidal
1. Lyophilic Colloidal :-
- Lyo means solvent .
- Lyophilic colloidal are solvent loving colloidal.
- They are hydrophilic and lipophilic types-
Hydrophilic Colloidal include gelatin or acacia which form colloidal dispersion in water.
Lipophilic colloidal include rubber or polystyrene which forms colloidal dispersion in organic solvent.
eg.:- benzene
They are thermodynamically stable. Viscosity increase with adding dispersed phase.
2. Lyophobic colloidal:-
- They are knowns as solvent hating colloids.
- When dispersion medium is water they are knowns hydrophobic colloids.
- eg.:- Colloidal dispersion of gold or silver in water.
- they are thermodynamically unstable.
- Viscosity does not increase an adding dispersed phase.
3. Association Colloids :-
- They are also knowns as amphilic colloids.
- Few molecules or ions have both polar and non-polar groups.
- They exists separately and associate at critical micelle concentration to form micelle of colloidal size.
- Viscosity increase by adding amphiphiles..
