Classification of Colloids
Colloids do not involve only solids and liquids, they may also involve gases.So, colloids are classified according to the physical state of dispersed phase (solute) and the dispersion medium (solvent). Most of the colloids can be classified into the following seven groups :
(i) Sol
(ii) Solid sol
(iii) Aerosol(vii) Gel
(iv) Emulsion
(v) Foam
(vi) Solid foam
(vii) Gel
All these are the technical names of the groups of colloids.We will now describe all these colloids in brief.
1.Sol.Sol is a colloid in which tiny solid particles are dispersed in a liquid medium. The examples of sols are :Ink, Soap solution, Starch solution and most Paints.
2.Solid sol.Solid sol is a colloid in which solid particles are dispersed in a solid medium. The example of a solid sol is :Coloured gemstones (like Ruby).
3.Aerosol.An aerosol is a colloid in which asolid or liquid is dispersed in a gas (including air).The examples of aerosols in which a solid is dispersed in a gas are :Smoke (which is soot in air) and Automobile exhausts.The examples of aerosols in which a liquid is dispersed in a gas are : Hairspray, Fog,Mist and Clouds.
4.Emulsion.An emulsion is a colloid in which minute droplets of one liquid are dispersed in another liquid which is not miscible with it. Examples of emulsions are : Milk,Butter and Face cream.
5.Foam. The foam is a colloid in which a gas is dispersed in a liquid medium. The examples of foam are :Fire-extinguisher foam ; Soap bubbles, Shaving cream and Beer foam.
6.Solid foam.The solid foam is a colloid in which a gas is dispersed in a solid medium.The examples of solid foam are : Insulating foam, Foam rubber,Sponge and Bread.
7.Gel. The gel is a semi-solid colloid in which there is a continuous network of solid particles dispersed in a liquid.The examples of gel are : Jellies,Gelatine and Hair gel.
We will now give the classification of colloids in a tabular form for your ready reference.
Notes
Matter in Our Surroundings - Notes
1. The Case of a Liquid Solute Dissolved in a Liquid Solvent
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2. 11. Metals Usually Have a Silver or Grey Colour
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8. 3. Non-Metals are Bad Conductors of Heat and Electricity.
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9. 7. Non-Metals may be Solid, Liquid or Gases at the Room Temperature.
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10. 1. Separation by a Suitable Solvent
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12. To Study the Properties of a Colloid
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15. To Separate a Mixture of Alcohol and Water
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16. 6. Metals are Usually Strong. They Have High Tensile Strength.
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18. To Study the Properties of a Solution
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20. 3. Metals are Good Conductors of Heat and Electricity.
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23. Separation Of Mixture Of a Solid And a Liquids
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25. Chemical Formula for daily use material
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28. To Study the Properties of a Compound of Iron and Sulphur
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32. 6. Non-Metals are Not Strong. They Have Low Tensile Strength.
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34. 4. Metals are Lustrous (or Shiny), and can be Polished.
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37. 7. Metals are Solids at the Room Temperature
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42. To Separate the Salt-Water Mixture (or Salt-Solution)
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43. Separation of Mixture Of Two Solids
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47. 11. Non-Metals Have Many Different Colours.
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