6th Class Science Separation of Substances Methods of Separation

     Methods of Separation

Some methods of separation has been discussed below:

Threshing: This method is used to separate grains from their stalks. In this method stalks of grains are beaten to separate grains.

Threshing is done by hands, by machines or by cattle.

Winnowing: This method is used to separate husk from grains with the help of wind..

Husk is very light whereas grains are comparatively heavy. So when mixture of husk and grains are slowly fallen down from a height, wind carry away the husk.

Thus husk is separated from the grains.

Hand-picking: By this method, undesirable substances like small pieces of stones are picked out and separated from the grains by hands.

Sieving: This method is used to separate the constituents of a mixture whose particles are of different sizes.

Sedimentation and decantation: By this method insoluble solid particles present in a liquid is separated out.

Insoluble solid particles, which are heavier than the liquid, are allowed to settling down at the bottom of the container by keeping the solution undisturbed for sometime. This process is called sedimentation. The liquid is then poured out from the container without disturbing the sediments. This process is known as decantation.

Loading: Fine solid particles have very small weight therefore they do not easily settle down in a liquid.

Loading is the process of adding weight to the fine solid particles so that solid particles easily settled down in the liquid.

Filtration: By this method insoluble solid particles present in a liquid are separated using a filter paper.

Evaporation: By this method dissolved solid particles in a liquid are separated out. In this method liquid is evaporated by heating. When all the liquid is evaporated, dissolved particles are left behind as a solid residue.

Distillation: This is the method of separating a liquid from a mixture of liquids having different boiling points. The liquid to be separated is evaporated and its vapor is then collected after it condenses.

Saturated Solution:

A solution in which no more substance can be dissolved at that temperature, is called saturated solution.

Note : Water can dissolves large number of substances, therefore, water is called universal solvent.

      Which one of the following is a pure substance?

(a) Iron 

(b) Silver

(c) Copper

(d) All of these

(e) None of these

Answer: (d

      Which one of the following methods is used to separate the constituents of a mixture whose particles are of different sizes?

(a) Loading

(b) Evaporation

(c) Sieving

(d) Distillation

(e) None of these

Answer: (c)

Pure substance are made up of only one kind atoms or molecules.

In a mixture different substances are mixed together.

A mixture having uniform composition is known as homogeneous mixture.

A mixture having non-uniform composition is known as heterogeneous mixture.

Threshing, winnowing, hand-picking etc. are the methods of separation..