Separation of Substances, Class 6 Science Chapter 5, NCERT Solutions for Class 6 Science Chapter 5, Class 6 Science, NCERT Solutions Chapter 5, Separation of Substances,NCERT Solutions for Class 6 Science Chapter 5 Separation of Substances

Chapter 5

Separation of Substances

We have so many substances in our surroundings and there is a need to separate the unwanted substances from it. We have noticed in our surroundings that how a substance is separated, for example, Butter from lassi, a strainer is used to separate tea leaves, etc. Butter is separated by the milking process called Churning.

Churning and filtration
Churning and Separation of tea leaves (Churning pic source: NCERT 6th class book)

Grains are separated from different stocks; sometimes we separate chilies and unwanted material from our poha and fried dal. We have to remove or separate stones from rice and pulses (dal) for proper consumption. Separation of substances is an important step for the removal of the harmful or non-essential substances from our food.

Hand picking method of Separation

Separation by handpicking
Method of Separation by Hand

Grains are separated from stocks and the process is called Threshing. We have seen threshers in the field where wheat or rice is harvested. Stalks are dried before threshing, Stocks are beaten by hand or machines can be used for threshing.

Threshing process done by combine
Threshing Process (Pic Source: Pixabay)

This method uses air to separate particle on the basis of their weight, lighter substances will fly away and heavier will fall on the ground and can be separated. This method used for separating grains from the husk, the grain will settle down and husk will fly away and can be used as feeding material for animals.

Winnowing the method of separation

  • We have seen these methods at our home for separating Atta or refined flour to get rid of bigger chunks of wheat and unwanted materials.
  • Sieving allow fine particles to pass, in flour mill, this method is used to separate wheat, rice, pulses, etc. and remove unwanted material and husk.
Sieving, where it can be done
Sieving (Source: NCERT 6th class)

Sedimentation, Decantation and Filtration
Sometimes the previous methods can’t be used for separating smaller particles like sand, dust, etc., at our home when rice and pulses are washed, water becomes muddy due to the deposition of the sand or dust particles.

A heavier particle settles down and lighter particles will float upon adding water is called as Sedimentation.

When water along with dust is removed process is called as Decantation, (Decant is called as liquid free from particles) two liquid which can’t be mixed (Immiscible liquids) can be separated by this method and the top layer is separated by tilting the vessel.

  • Tea can be separated by a process called as Filtration to remove unwanted tea leaves, sometimes we can use decantation for tea but leaves can be left.
  • Water is filtered to remove impurities and unwanted materials, fruit and vegetable juices are filtered to get rid of seeds and bigger chunks.

  • If we boil water for a long time, the quantity will be decreased, water gets evaporated and the process of conversion of water into its vapors is called Evaporation.
  • Evaporation is taking place where ever water is present if conditions are suitable.
  • Sometimes we have to use more than one method for the separation of substances.
Evaporation of water and extraction of salt
Evaporation of water and extraction of salt

When steam or vapors come into contact with the cold surface it gets condensed, for example, water drops on the outer side of a cold glass of liquid or ice.

Condensation process

When any solute or substances is added again and again and no more dissolving occurs after a certain quantity, the solution is said to be saturated. At saturation point, no more dissolving occurs. But, if we heat the solution the remaining soluble substance is going to get dissolved and that state would be called unsaturation.

Saturation and Unsaturation
Saturation and Unsaturation


1. Why do we need to separate different components of a mixture? Give two examples.
Answer: The separation of components is needed due to the reason that the components are not always pure, they may have some impurities and we have to separate them for our purpose to use them.
For example: 

  • Separation of stones from rice and pulses.
  • Separation of tea leaves from the tea.

2. What is winnowing? Where is it used?
Answer: When we separate impurities with the help of wind it is called winnowing. We use winnowing for the separation of lighter particles from the heavier particles.

3. How will you separate husk or dirt particles from a given sample of pulses before cooking?
Answer: We separate these impurities from the pulses by handpicking.

4. What is sieving? Where is it used?
Answer: In this method, the fine particles or particles having smaller size pass through filter or sieve and bigger particles remain unfiltered.  This method is used in flour mills to separate the husk from wheat also used for husk removal from pulses.

5. How will you separate sand and water from their mixture?
Answer: We can separate sand and water, by keeping the mixture untouched for a few minutes and sand will get deposited in bottom and we can get water.

6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer: Yes, we can separate the sugar from mixed wheat flour. First of all, mix the mixture in water so the sugar gets dissolved and then we separate the sugar water and wheat flour remains undissolved.

7. How would you obtain clear water from a sample of muddy water?
Answer: We can leave this sample for a few minutes to settle down, mud will settle down in the bottom and we can separate water.

8. Fill up the blanks
(a) The method of separating seeds of paddy from its stalks is called Threshing.
(b) When milk, cooled after boiling, is poured onto a piece of cloth the cream (malai) is left behind on it. This process of separating cream from milk is an example of Churning.
(c) Salt is obtained from seawater by the process of Evaporation.
(d) Impurities settled at the bottom when muddy water was kept overnight in a bucket. The clear water was then poured off from the top. The process of separation used in this example is called Sedimentation.

9. True or false?
(a) A mixture of milk and water can be separated by filtration. False
(b) A mixture of powdered salt and sugar can be separated by the process of winnowing. False
(c) Separation of sugar from tea can be done with filtration. False
(d) Grain and husk can be separated from the process of decantation. False

10. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to add ice to cool it. Should you add ice to the lemonade before or after dissolving sugar? In which case would it be possible to dissolve more sugar?
Answer: As we have studied in this chapter that the process of solubility increases when the temp. is high so the best time to add ice is after the mixing of the sugar in lemonade. If we add sugar in cold water then the sugar will take time to dissolve.

Keywords: Churning, Condensation, Decantation, Evaporation, Filtration, Handpicking, Solution, Winnowing, Threshing, Sieving, Sedimentation, Saturated the solution, NCERT 6th class, Separation of Substances, CTET, CTET Paper-II, TGT, KVS,

Image Source: Pixabay, recreation work is done by Anil Kashyap

NCERT Class 6th Science
Chapter 4: Sorting Materials into Groups

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