[Ncert Science Notes]* Ncert Science Class VI | Chapter 5. SEPARATION OF SUBSTANCES

 CHAPTER – 5 

SEPARATION OF SUBSTANCES 

• Handpicking, winnowing, sieving, sedimentation, decantation and filtration are some of the methods of separating substances from their mixtures. 

• Methods of separation: 

(i) Separation of solid from other solids: 

(a) Threshing: Process by which the grains are released from the chaff. 

(b) Winnowing: The process of separation of heavier and lighter components of a mixture by wind or blowing air. 

(c) Hand-picking: The process by which undesirable components are just picked up by hand. 

(d) Sieving: The process by which separate solid constituents of a mixture which differ in their sizes. 

(e) Magnetic separation: Process by which magnet is moved over such a mixture, the magnetic material sticks to it and is removed. 

(ii) Separation of water soluble solids: 

(a) Evaporation: Process by which the conversion of liquid state into gaseous state on heating. 

(b) Condensation: Process by which conversion of gaseous state into liquid state on cooling. 

(iii) Separation of insoluble solids from Liquids: 

(a) Sedimentation: It allows heavier matter to settle down. Example: sand, water. 

(b) Decantation: The methods of separating insoluble solids from liquids. 

(c) Loading: The methods by which finer particles are made to settle faster by dissolving a small quantity of alum. 

(d) Filtration: The liquid that collects in the beaker is called filtrate. 

(iv) Separation of Immiscible Liquids: 

(a) Funnel: The method of separting mixture of oil and water.

(b) Centrifugation: The method in which mixture containing suspended particles is rotated at a high speed in a centrifuge and heavier particles settle down. It is used for separating cream from milk. 

(c) Churning: The method which is used for separating lighter particles of solid suspended in a liquid. Example: butter from curd. 

• Husk and stones could be separated from grains by handpicking. 

• Husk is separated from heavier seeds of grain by winnowing. 

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

• More of a substance can be dissolved in a solution by heating it. 

• Water dissolves different amount of soluble substances in it.