NCERT Class 6 Science Chapter 5: Separation of Substances YouTube Lecture Handouts

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NCERT Class 6 Science Chapter 5: Separation of Substances

Hand Picking

• Slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses

• Quantity of impurity is not very large

Threshing

• Stalks are dried in sun and grains separated

• Separate grains from stalks (sometimes stalks are beaten by hand, bullocks or machines)

Winnowing

Separate components of mixture based on weight – separate heavy and light components by blowing air

Sieving

• Separate bigger impurities from smaller impurities

• Removes pieces of stones, stalk and husk that may still remain with wheat after threshing and winnowing.

Sedimentation, Decantation & Filtration

• When the heavier component in a mixture settles after water is added to it, the process is called sedimentation.

• When the water (along with the dust) is removed, the process is called decantation

• Filtration - impurities are removed (smaller in size) – used in making soup, juices, paneer (cottage cheese) at home

In a mixture of water and a solid, the heavier particles get settled. The water above the settled particles can be removed. In order to further remove the finer particles, a cloth or a filter paper can be used. Mud can be separated from muddy water by sedimentation, decantation and filtration to give the clear water

Evaporation

• Process of conversion of water into vapor – it is continuous wherever water is present

• When the salt solution is heated, water gets evaporated leaving behind the salt. Salt from the salt solution can be obtained

💡How to Separate Sand and Salt Mixture?

Conversion of water vapour to liquid form is called as condensation

Solutions

• Solute (salt) + Solvent (water) = Solution

• Saturated Solution: A given amount of water dissolves only a definite amount of a substance (salt) at a given temperature.

• A saturated solution is one in which no more of that substance can be dissolved.

• Increase saturation limit by heating

• Different substances dissolve to different extent in equal volumes of water

• Difference in the size of particles in a mixture is utilized to separate them by the process of sieving and filtration

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