Colloids

Question 1 What are colloids.Give example?

Question 2 What do you mean by Tyndall effect?

Question 3 Give properties of colloids?

Question 4 What are sol.Give example?

Question 5 What are aerosol.Give example?

Question 6 What are emulsions.Give example?

Question 7 What are foam.Give example?

Question 8 What is the difference between solution and colloids?

COLLOIDS

A solution in which the size of solute particles is intermediate between those in true solution and suspension.

For Ex: Soap Solution,Starch solution,milk,Blood,ink etc.

Properties
1) They appear to be homogeneous but actually they are heterogeneous when observed under microscope.

2)They are not perfectly transparent,it is somewhat translucent.

3)The particles cannot be seen by naked eyes or microscope.

4)The particles do not settle on keeping.

5)The particles cannot be separated by filtration.

6)The particles are big enough to scatter light.

7)The size of particles is bigger than those of true solution but smaller than suspension.

If a beam of light is put on a colloidal solution,kept in a beaker in a dark room,path of light beam is illuminated and become visible when seen from the side.

The path of light beam becomes visible because colloidal particles are big enough to scatter light falling on them in all direction.

tyndall effect

The scattering of light by colloidal particles is called TYNDALL EFFECT.

A true solution does not scatter a beam of light passing through it but colloidal solution scatter a beam of light.

      TYPES OF COLLOIDS 

Name of Colloid Dispersed Phase Dispersed Medium Example
1)    Sol Solid Liquid Ink,Soap Solution,Paints
2)    Solid Sol Solid Solid Coloured Gemstones
3)    Aerosol a)Solid

b)Liquid

Gas

Gas

Smoke,

Automobile exhaust

Fog,Mist,Cloud

4)    Emulsions Liquid Liquid Milk,Butter,

Cream

5)    Foam Gas Liquid Shaving Cream,Soap Bubbles
6)    Solid Foam Gas Solid Insulating Foam,Foam Rubber,sponge
7)    Gel Solid Liquid Jellies,Gelatin

 

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