Ch – 5 Separation Of Substances

  • We separate substances because –
  • 1 – To get useful components from that mixture.
  • 2 – To remove non-useful components.
  • 3 – To remove impurities.
  • 4 – To remove harmful components.
  • The substances to be separated may be particles of different sizes or materials.
  • These may be in any three states of matter i.e., solid, liquid or gas.
  • The method of handpicking can be used for separating slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses.
  • The process that is used to separate grain from stalks etc. is threshing. In this process, the stalks are beaten to free the grain seeds.
  • Winnowing is used to separate heavier and lighter components of a mixture by wind or by blowing air.
  • This method is commonly used by farmers to separate lighter husk particles from heavier seeds of grain.
  • The separated husk is used for many purposes such as fodder for cattle.
  • Sieving allows the fine flour particles to pass through the holes of the sieve while the bigger impurities remain on the sieve.
  • Sieving is used when components of a mixture have different sizes.
  • 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.
  • If a mixture of immiscible liquids is allowed to stand for some time, they form two separate layers. The component that forms the top layer can then be separated by decantation.
  • The process of conversion of water into its vapour is called evaporation.
  • The process of conversion of water vapour into its liquid form is called condensation.

Published by Priya Prakash

In the midst of winter, i found there was within me an invincible summer ~ Albert Camus

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