Separation of Substances – CBSE NCERT Science

Separation of Substances – CBSE NCERT Science (Biology)

NEED FOR SEPARATION

To remove the undesirable or harmful components.
To remove the impurities and getting a pure substance.
To separate useful components.

METHODS OF SEPARATION

SEPARATION OF SOLIDS FROM OTHER SOLIDS

HANDPICKING

Removing of undesirable solid components or impurities like pieces of stone or broken pieces of glasses from useful solid by hand.

This method is usually used when the mixture contains solids of different colors,
shapes and sizes…and the component to be separated is present in small quantity …
usually used for cleaning pulses and rice before cooking .

SIEVING

Used to separate components of a mixture which are of different sizes with the help of a sieve… which is a mesh held in a frame.The fine components pass through the sieve and the bigger components remain on the sieve.

SIEVING FLOUR FOR BAKING A CAKE

SIEVING AT THE CONSTRUCTION SITE

THRESHING

Process of separating grains from stalks.

WINNOWING

Lighter components of a mixture  separated from heavier ones by wind or by blowing air.

Used by farmers to remove husk from grains.

INSOLUBLE SOLIDS FROM LIQUIDS

RICE SOAKED IN WATER

SEDIMENTATION

Process in which heavier particles of an insoluble solid in a liquid settle down.The solid particles called SEDIMENTS settle down forming a layer.

DECANTATION

Sedimentation is followed by decantation.

It’s the process of pouring out of the upper clear liquid into another container without disturbing the sediments.

FILTRATION

Process by which an insoluble solid is separated from a liquid by using a filter.A filter is a medium with very fine pores.

USED FOR:

PREPARING COTTAGE CHEESE AT HOME

REMOVING PULP FROM FRESH FRUIT JUICE

CLEANING MUDDY WATER

SEPARATION OF SOLUBLE SOLIDS FROM LIQUIDS

EVAPORATION AND CONDENSATION

Process of converting a liquid into its vapor form is called evaporation.

When heat is applied the liquid component evaporates leaving behind the solid component behind.

The liquid component can be recovered by condensation.

The common salt that we use in our food is obtained by evaporating SEA WATER.

SEPARATION OF TWO IMMISCIBLE LIQUIDS

SEPARATING FUNNEL

The mixture is put into a separating funnel .. the lighter liquid forms the upper layer.

The denser liquid which forms the lower layer is poured out of the funnel through the stop cock.

MIXTURES ARE USUALLY SEPARATED BY USING A COMBINATION OF METHODS

SEPARATING A MIXTURE OF SAND SALT AND WATER

Filtration
Evaporation
Condensation