Page 1 - Lesson note 4

SUBJECT-CHEMISTRY

CHAPTER-SURFACE CHEMISTRY

SUBTOPIC-Colloidal solution, types of colloids

KEY NOTES:

 The solution in which the size of the particles are in between 1-1000nm or
-6
-9
10 to 10 m is called colloidal solution.
 Colloidal solutions are inter mediate between true solutions and
suspension.

 A colloidal system consists of two phase the dispersed phase and the
dispersion medium.

 Classification:

(1)Based on Physical state of the dispersed phase and dispersion

medium.

Dispersed Dispersion Type of Examples
phase medium colloid
Solid Solid Solid sol Some coloured glasses and gem
Solid Liquid Sol stones
Solid Gas Aerosol Paints, cell fluids
Liquid Solid Gel Smoke, dust
Liquid Liquid Emulsion Cheese, butter, jellies
Liquid Gas Aerosol Milk, hair cream
Gas Solid Solid sol Fog, mist, cloud, insecticide sprays
Gas Liquid Foam Pumice stone, foam rubber
Froth, whipped cream, soap lather
 If the dispersion medium is water the colloidal solution is called
hydrosol, if medium is benzene then it is called benzosol , if the

medium is alcohol then it is called alcosol.

 Classification Based on Nature of Interaction between Dispersed Phase and
Dispersion Medium :
(i) Lyophilic colloids (lyo-means solvent and philos means loving)

The colloidal solution in which the dispersed phase has more affinity
towards dispersion medium is called lyophilic colloid.
Example-solution of starch, gelatin, gum, rubber.