Class 6 Science Chapter 5 Separation of Substances, Sedimentation, Decantation, Filtration (For CBSE, ICSE, IAS, NET, NRA 2022)

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Separation of Substances

Sedimentation

  • This is a process to separate solids suspended in a liquid.
  • The substance shouldn՚t dissolve in the liquid.
  • The insoluble particles settle down at the bottom.
  • This technique is used for washing rice, the rice being insoluble gets accumulated at the bottom of the container.
  • Similarly soil and sand being insoluble in water settle down at the bottom.
  • This technique is also useful in separating two liquids which don՚t mix with each other and this is known as decantation.
Sedimentation, Decantation and Filtration

Decantation

  • It is the technique of separating immiscible liquids or a liquid and a solid substance.
  • Taking the example of oil in water, by pouring the mixture in another container oil which forms the upper layer can be easily separated.
  • It has been observed that sometimes along with water the small dirt particles get carried away that needs to be further removed and this can be done using filtration process.

Filtration

  • In this process smaller particles like dirt etc. are separated by passing the solution through a medium i.e.. , a filter paper.
  • The dirty solution is allowed to pass through the cone-like structure of the filter paper.
  • This process is very useful in separating paneer from milk.

Some Other Important Terms

Evaporation

  • It is the process by which water changes from a liquid to a gas or vapor.
  • This process is often used for extracting salt from saltwater.

Condensation

  • It is the process of converting water vapour into its liquid.
  • This process is responsible for the formation of clouds.

Saturated Solution

  • It is the solution which contains the maximum amount of solute that is capable of being dissolved.
  • An example is that of NaCl, NaCl that will dissolve in 100 g of water is 36.0 g. If any more NaCl is added, it will not dissolve because the solution is saturated.

Churning

It is the process in which milk is shaked in order to allow lighter particles to come to the surface for making butter.

Pure and Impure Substance

  • A substance composed of only a single type of particle is called a pure substance whereas a substance consisting of mor than one type of particle is called an impure substance.
  • Some of the pure substances are Hydrogen gas, Gold metal, Ammonia, etc.
  • Some of the impure substances are air, sea water, petroleum, etc.

Sublimation

This is a process in which a solid directly gets converted into vapour.

Magnetic Separation

  • With the application of a magnetic force the metal gets separated from a mixture.
  • One of the examples is that of a mixture of salt and iron filings that can be separated using a magnet.

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