CBSE Class 6 Science Revision Notes Chapter 5

CBSE Class 6 Science Revision Notes Chapter 5 – Separation of Substances

CBSE Class 6 Science Chapter 5 Notes are concise and easily accessible from Extramarks’ website. Subject matter experts curate these accurate notes based on the NCERT books and the latest CBSE  guidelines.

Class 6 Science Chapter 5 Notes cover various terminologies, concepts, and explanations related to the separation of substances. The notes include all the types of substances, different methods of separation, and different processes a substance goes through for extraction from another substance.

Revision Notes for CBSE Class 6 Science Chapter 5 

Access Class 6 Science Chapter 5 – Separation of Substances

  • A piece of material with definite aspects and characteristics is a substance.
  • Substances are categorised into two types:
  1. Pure substance 
  2. Impure substance

 Pure Substance

  • Several substances only contain one type of component particle. These are known as pure substances.
  • Pure substances are made up of elements and compounds. 
  • Some prominent examples of pure substances are iron, copper, water, salt, etc.

Impure Substance

  • The substances that have numerous types of component particles are impure substances. 
  • Some common examples of impure substances are pond water, milk, etc.

Need for Separating Components of a Mixture

The components of a mixture or an impure substance are separated for the following purposes such as:

  • Getting rid of something that is either harmful or useless
  • Acquiring the required components
  • Pure samples can be obtained by removing the contaminants.

Methods of Separation

  • The attributes of the components in a mixture remain the same, such as particle size,  melting point, volatility, density, and boiling temperature.
  • A change in the above attributes can help in separating the components of a mixture.
  • The methods utilised for separation are as follows.
  1. Threshing
  2. Winnowing
  3. Handpicking
  4. Sieving
  5. Magnetic Separation
  6. Floating and Sinking Method
  7. Sedimentation and Decantation
  8. Loading
  9. Filtration
  10. Separation of Immiscible Liquids
  11. Churning 
  12. Sublimation
  • To separate the solid from other solids, methods such as threshing, winnowing, handpicking, sieving, and magnetic separation are used.
  • To separate water-soluble solids or soluble solutes in the solvent, methods such as evaporation and condensation are used.
  • To separate insoluble solids from liquids, methods such as sedimentation, decantation, loading, and filtration are used.
  • For the separation of immiscible liquids, methods such as funnel, centrifugation, and churning are used.
  • For extracting a non-soluble solute from a solvent, floating and sinking and sublimation methods are used.

Separation of Solid From Other Solids

  • Threshing
  • Threshing is the process of separating the grain from the husk.
  • The grains are separated from the stalks after the crops have been harvested or the dry stems are cut.
  • The grains can be separated by bare hand or with the help of equipment. 
  • Threshing involves manually grasping a pile of grain and then pounding it against a rock or a hard surface.
  • The pounding loosens the grain and detaches it from the stalk.
  • Bullocks are occasionally used to crush the accumulated stalks.
  • Machines such as a combined harvester can be used along with traditional threshing.
  • There are seed coatings and small pieces of leaves or stems that are present in grains after threshing. These are collectively known as chaff. Winnowing is also used to segregate them.
  • Winnowing
    • Winnowing is the technique used to segregate the chaff from grain with the aid of the wind.
  • To segregate heavier and lighter components of a mixture, wind or blowing air is used.
  • The farmer sets the combination of chaff and grain inside a winnowing basket and stands at a higher level allowing the mixture to fall to the ground.
  • The grain drops almost vertically as it is heavier, while the lighter chaff is brushed away by the wind.
  • The segregated chaff is used to make the cattle feed.
  • The important factor in winnowing is the wind’s direction.
  • Hand-Picking
  • In this process, unwanted elements are lifted by hand.
  • In hand-picking techniques, when the quantity of the combination is small, the undesired constituent is of lesser quantities, and the other attributes of the unwanted substance vary from that of the useful one.
  • Sieving
  • It is the technique for segregating solid portions of a mixture of different sizes.
  • The larger component is left behind while the smaller component moves through the sieve’s pores. This approach is used by some people to detach wheat bran (larger components) from flour in their houses.
  • The process of sieving is also used to segregate pebbles and stones from the sand at construction sites. The stones and pebbles in the mixture are left in the sieve whereas the fine sand particles pass through the sieve.
  • A sieve is a tool that has several minute holes through which fine particles can pass through.
  • Magnetic Separation

When a magnet is stirred over a magnetic mixture, the magnetic material clings to the magnet and is separated.

Separation of Water Soluble Particles

  • Evaporation

The procedure of conversion of a liquid state to a gaseous state in the presence of heat is called evaporation.

  • Condensation

The conversion process from a gaseous state to a liquid state when cooled is known as condensation.

Separation of Insoluble Solids From Liquids

  1. Sedimentation
  • The procedure in which large and insoluble components of a mixture settle at the bottom when left idle for a period of time is sedimentation.
  • For example, a mixture of sand and water.
  1. Decantation

Decantation is the process of carrying the clean liquid by keeping the sediment untouched.

  1. Loading

The method of dissolving a small amount of alum can be used to accelerate the settling of finer particles.

  1. Filtration
  • In this process, impurities are moved through a filter. The filter’s pores only allow liquids to pass through, and it segregates suspended particles and solid particles.
  • The clear liquid attained is the filtrate, while the substance left on the filter paper is called the residue.

Separation of Immiscible Liquids

  • Funnel
  • In this process, the mixture is passed through a filtration apparatus to separate an insoluble component from the liquid.
  • Oil and water mixtures are segregated in this process.
  1.   Centrifugation
  • A liquid consisting of suspended particles is spun at a high speed with the help of a centrifuge, which causes the heavier particles to settle down. 
  • Milk is separated from cream through this process.
  1.   Churning
  • To separate the lighter solid particles suspended in a liquid, the process of churning is used.
  • The process of churning is used in making butter from curd.

Separating Solute not Soluble in a Solvent

  • Flotation and Sinking Method

The flotation and sinking method is used where both the constituents are not soluble in water and one of the constituents of a mixture is lighter than water while the other is heavier than water.

  1.   Sublimation

Sublimation is the procedure of transforming a solid into vapour without changing to a liquid state. 

  • Handpicking is used to extract grains from husks and stones.
  • The husk is segregated from the heavier grain seeds by the process of winnowing. 
  • A solution in which more of a substance cannot be dissolved is a saturated solution. 
  • To dissolve more of a substance, a solution is heated.
  • Soluble compounds of distinct amounts can dissolve in water.

Class 6 Chapter 5 Science Notes – Separation of Substances – Chapter Overview

The CBSE curriculum includes this chapter for students to gain an understanding of how substances can be separated and what methods are used to achieve it. The revision notes provided by Extramarks enhance their ability to grasp these concepts with authentic and concise content which follow the CBSE instructions.

Separation of Substances Class 6 Notes explain the rudimentary concepts of impure substances and pure substances, and techniques that can be used to segregate if combined in a mixture. 

Students can easily access these comprehensive notes from Extramarks’ website. These notes are made according to the revised CBSE guidelines by subject matter experts.

FAQs (Frequently Asked Questions)

1. Explain the process of threshing.

After harvesting the crop, bundles of wheat or paddy stalks are seen lying in the fields. The grain is separated from stalks after they are dried in the sun. Every stalk has several grain seeds connected to it. As grains are minute, it would be difficult to pluck them from their stalks. Therefore, threshing is utilised to separate the grain from stalks and chaff.


2. What is condensation?

When the steam touches the metal plate cooled with ice, it further condenses and produces liquid water. The condensation of steam causes water drops to fall from the plate. The procedure of transforming water vapour into its liquid form is known as condensation.