Collision Class Xii

Index
1. Introduction
2. Colloidal Dispersions
3. Classification of Colloids
4. Hydrocolloids
5. Dispersed Systems
6. Stabilization of Colloidal Dispersion
7. Destabilization of Colloidal Dispersion
8. Properties of Colloidal Solutions
9. Application of Colloids
10. Bibliography


COLLOID->
Introduction:
A colloid or colloidal dispersion is a type of homogenous mixture. A colloid consists of two separate phases: Dispersed phase & Continuous phase. The Dispersed phase is made of tiny particles or droplets that are distributed evenly throughout the continuous phase. Homogeneous mixtures with a Dispersed phase in the size range 1 Nm to100 nm may be called colloidal aerosols, colloidal emulsions, colloidal foams, colloidal dispersions or hydrosols . If a colloidal has a solid phase dispersed in a liquid, the solid particles will not pass through a membrane, where as the dissolved ions or molecules of a solution will pass through. Some colloids are translucent due to Tyndall effect(scattering of light by particles in colloid).Some of the examples of colloids include butter, milk, aerosols (fog, smoke), paints, glues etc. This field of study was introduced in 1861 by Scottish scientist “Thomas Graham”.

Colloidal Dispersions
>> Solute doesn’t completely dissolve in solvent but not visible to the naked eye.
>> Will Scatter light – gives an opaque , turbid appearance
>> Exhibits characteristics of a molecular solution (Brownian motion, capacity for diffusion)
>> Size 1 nm - 0.5 nm

Classification of Colloids
-> Colloids can be classified on the basis of interaction between Dispersed phase (DP) & Dispersion medium (DM):

a) Lyophillic colloids / Hydrophilic colloids :
(i) Strong affinity is present between particles of DP & DM.(ii) It’s reversible because DP & DM can be separated.(iii) It’s stable & don’t get easily precipitated.(iv)When DM is water , it’s called Hydrophilic.

b) Lyophobic colloids / Hydrophobic colloids :
(i) No or very low...