Methods of Separation II


LearnNext Lesson Video

Methods of separation of substances under wet conditions
Some solid particles are insoluble in
water. For example chalk powder, dust particles, sand, and tiny pieces of straw are insoluble in water. To separate this type of particles generally we use the following methods

Sedimentation and Decantation
The process of separating insoluble substances which are heavier than liquid by allowing them to settle down on their own due to gravity is called sedimentation. The particles which settle down during sedimentation are called sediments.
Decantation follows sedimentation. In this process the clear upper liquid is poured out from the container without disturbing the sediment. The upper clear liquid is called supernatant.

For example muddy
water contains heavier particles like sand and soil. Leave this muddy water undisturbed for some time. The heavier soil and sand particles settle down. And the clear upper water is poured out from the container.

Filtration is a process by which insoluble solids can be removed from a liquid by using a filter paper.
A filter paper is a special type of paper which has pores that are tiny enough to let only liquids pass through it. If you pass a solution through filter paper, any undissolved solid particles will get left behind on the paper whereas the liquid will filter through.
The liquid that passes through is called the filtrate and the undissolved solid particles are called residue. 
Example: A mixture of chalk powder and
water can be separated by this method.

To separate the soluble solids form liquids we use
evaporation and condensation methods. 

The process of conversion of
water into vapour by heating it to its boiling point is called evaporation.
The salt can be easily obtained from the salty
by the process of evaporation. If we boil this water, the water evaporated completely, leaving behind only the salt.

The process of conversion of
water vapour into its liquid form is called condensation.
Example: The
water vapour condenses and we receive the same water in the form of rain.
If you pour cold
water in a glass, you will observe the formation of water droplets on the outer surface of the glass . This is due to the condensation of water
vapour present in atmosphere.

Separation of substances using more than one method
A mixture of sand and salt can be separated by combination of methods. The first method is sedimentation and decantation. This mixture is put in water and left for the sand to settle for some time. Then, we will decant the salty water, which will separate the sand from the mixture. Now the
salt can be separated from the water by evaporation. The water will boil away, leaving the salt behind. So, the mixture of the sand, salt and water has been separated successfully using a combination of sedimentation, decantation, evaporation and condensation.

Solution and solubility
A solution is prepared by dissolving a substance in a liquid.
Solute + Solvent = Solution
Salt +  
water = Salt solution

Saturated solution
A solution is said to be saturated if it cannot dissolve more of the substance in it at a particular temperature.

Unsaturated solution
A solution is said to be unsaturated if it can dissolve more of the substance in it at a particular temperature.

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Activities & Simulations

Activity 1 
has created student friendly animation on “Methods Used for Separation of Substances”. This animation imprints the various separation methods in students mind. This activity also explain why separating mixing up material can be useful. It explain each technique with an appropriate example along with good animation. At the end of the activity students also get questions related to this activity.
Go To Activity

Activity 2 has created an interactive video on “Methods of Separating Mixtures”. Students learn different separation methods on their own by doing activities. This activity also has interactive session in which students have different separating mixtures and apparatus. Student has to drag the separation mixture to the apparatus which would use to separate it. At the end of the activity students also get questions related to this activity.
Go To Activity

1 . what is the differece between sedimentation and decantation

Sedimentation is the process of settling down of heavy insoluble impurities. Decantation is pouring out of clear water.

2 . what is handpicking ? When is this method used?


Handpicking is a method to remove slightly larger impurities like pieces of dirt,stones and husk from wheat,rice and...

3 . How is salt obtained from sea water?

The sea water is first collected and it is kept for evaporation.When the water is fully evaporated the salt remains.By this way salt is obta...

4 . Define saturated solution . How would you prepare a saturated solution of sugar in water


As the temperature of the solvent increases, solubility increases. Additionally, pressure and the nature of the solut...

5 . what is sieving? where is it used?


An instrument with a meshed or perforated bottom used for seperating impure substances from fine substances or for s...