NAVODAYA VIDYALAYA SAMITI

B-15, Institutional Area, Sector 62, Noida, Uttar Pradesh 201307

E-CONTENT FOR CLASS VI

SUBJECT:- SCIENCE

CHAPTER:- SEPARATION OF SUBSTANCES

NAME OF THE CHAPTER:-��SEPARATION OF SUBSTANCES�CLASS : VI

PREPARED BY

P.VAMSEEDHAR

TGT-SCIENCE

JNV, SRIKAKULAM

ANDHRA PRADESH

Learning Objectives:-

Knowledge :- At the end of the chapter all the students will be able to

• Define the terms like condensation, evaporation decantation, sedimentation, solution, saturated solution
• Describe churning, hand picking , threshing, filtration and winnowing processes.
• Recall the various separation processes when come across in the daily life situations.

Understanding:- At the end of the chapter all the students will be able to

• Classify the various separation processes based on the usage in our daily life situations.
• Give suitable examples for the various separation processes.

​

​

​

​

​

​

​

​

​

​

Application:- At the end of the chapter all the students will be able to

• Apply the knowledge of various methods of separation processes in the day to day life

Skill:- At the end of the chapter all the students will be able to

• Appreciate the skill possessed by the farmers, labour, at home mothers skill of separating various things in the kitchen etc.
• Skill of drawing, using of a particular methods of separation process for a particular activity.

​

​

• In our daily life, there are many instances when we notice a substance being separated from a mixture of materials.
• Tea leaves are separated from the liquid with a strainer, while preparing tea.

• Grains are separated from stalks, while harvesting.
• Milk or curd is churned to separate the butter .
• Perhaps you might have eaten salted daliya or poha. If you found that it had chillies in it, you may have carefully taken them out before eating.

• Suppose you are given a basket containing different types of fruits and asked to separate them. What would you do?
• Pick out one kind and place them in a separate container, right? Seems easy, but what if the materials we want to separate are much smaller than mango or guava?

From the above examples it is clearly known that- why do we separate substances

​

• To separate two different but useful substances
• To remove non useful components
• To remove impurities or harmful substances

METHODS OF SEPARATION

​

• Hand picking
• Threshing
• Winnowing
• Sieving
• Sedimentation, decantation and Filtration
• Evaporation and Condensation

​

​

​

​

• This method is used to separate slightly large sized impurities like stones and husk from the rice or wheat by using hand.

HAND PICKING

• This method of hand picking can be used for separating slightly larger sized impurities like the pieces of dirt, stone, and husk from wheat, rice or pulses. The quantity of such impurities are usually not very large. In such situations, we find that handpicking is a convenient method of separating substances

HAND PICKING

THRESHING

• One may pluck mangoes or guavas from the trees.
• But, grain seeds are much smaller than mangoes or guavas. So, plucking them from their stalks would be impossible.
• How does one separate grain seeds from their stalks? The process that is used to separate grain from stalks etc. is Threshing.

THRESHING

• In threshing process, the stalks are beaten to free the grain seeds . Sometimes threshing is done with the help of bullocks. Machines are also used to thresh large quantities of grain.

WINNOWING

• The method of separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing.
• This method is commonly used by farmers to separate lighter husk particles from heavier seeds of grain
• The husk particles are carried away by the wind. The seeds of grain get separated and form a heap near the platform for winnowing. The separated husk is used for many purposes such as fodder for cattle.

WINNOWING PROCESS

• Sometimes, we may wish to prepare a dish with flour. We need to remove impurities and bran that may be present in it. What do we do? We use a sieve and pour the flour into it.
• This method of separation of different sized particles of a solid mixture is called as Sieving.

Sieving

Sieving

• Sieving allows the fine flour particles to pass through the holes of the sieve while the bigger impurities remain on the sieve. In a flour mill, impurities like husk and stones are removed from wheat before grinding it. Usually, a bagful of wheat is poured on a slanting sieve. The sieving removes pieces of stones, stalk and husk that may still remain with wheat after threshing and winnowing.

​

• Sometimes, it may not be possible to separate components of a mixture by winnowing and handpicking. For example, there may be lighter impurities like dust or soil particles in rice or pulses.
• How are such impurities separated from rice or pulses before cooking?

​

SEDIMENTATION AND DECANTATION

• When the heavier component in the 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

​

• The same principle is used for separating a mixture of two liquids that do not mix with each other. For example, oil and water from their mixture can be separated by this process. If a mixture of such 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.

• Sometimes, water supplied through taps may be muddy. The water collected from ponds or rivers may also be muddy, especially after rains. Let us see if we can use some method of separation to remove insoluble impurities like soil from the water.

`FILTRATION

• If the water is still muddy, impurities can be separated by a filter that has even smaller pores.
• A filter paper is one such filter that has very fine pores in it. shows the steps involved in using a filter paper. A filter paper folded in the form of a cone is fixed onto a funnel .
• The mixture is then poured on the filter paper. Solid particles in the mixture do not pass through it and remain on the filter.

​

FILTRATION

• Filtration can be used to separate components of mixture of an insoluble solid and a liquid. Fruit and vegetable juices are usually filtered before drinking to separate the seeds and solid particles of pulp

EVAPORATION

• Add two spoons of salt to water in a beaker and stir it well. Do you see any change in the colour of water? Can you see any salt in the beaker, after stirring? Heat the beaker containing the salt water. Let the water boil away.
• What is left in the beaker? In this activity, we used the process of evaporation, to separate a mixture of water and salt.

​

EVAPORATION

• Evaporation is the process in which a liquid gets converted into vapour.
• Evaporation can be used to separate a solid dissolved in a liquid.

Obtaining salt from seawater

EVAPORATION AND CONDENSATION

• When the steam comes in contact with the metal plate cooled with ice, it condenses and forms liquid water. The water drops that you observed falling from the plate, were due to condensation of steam. The process of conversion of water vapour into its liquid form is called condensation.

EVAPORATION AND CONDENSATION

USE OF MORE THAN ONE METHOD OF SEPARATION

• Often one method is not sufficient to separate substances. in such a situations we need to separate the mixture by using more than one methods.
• EX :Sand salt mixture .

USE OF MORE THAN ONE METHOD OF SEPARATION

• Sand and salt mixture can be separated by using decantation, filtration, evaporation and condensation methods.

Can water dissolve any amount of a substance?

• we found that many substances dissolve in water and form a solution. We say that these substances are soluble in water. What will happen if we go on adding more and more of these substances to a fixed quantity of water
• Add one teaspoonful of salt and stir it well, until the salt dissolves completely Again add a teaspoonful of salt and stir well. Go on adding salt, one teaspoonful at a time, and stir. After adding a few spoons of salt, do you find that some salt remains undissolved and settles at the bottom of the beaker? If yes, this means that no more salt can be dissolved in the amount of water we have taken. The solution is now said to be saturated.

UNSATURATED AND SATURATEDSOLUTION

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

​

• Ex : SALT SOLUTION

Things To Think About…..

• Find the solutions for the following
• How will you separate husk or dirt particles from a given sample of pulses before cooking?
• Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
• How will you separate sand and water from their mixture?
• Collect and write down the information where the processes like sedimentation, decantation and filtrations(all three) are used in any two activities you come across in your daily life.
• Why the rag pickers handle a stick with magnet at the base?

Useful web links

• DIKSHA PORTAL

https://diksha.gov.in/cbse/play/collection/do_312796455254507520120350?contentType=TextBook

• https://nroer.gov.in/55ab34ff81fccb4f1d806025/searchresults/?search_text=separation+of+substances#results

ACKNOWLEDGEMENT

• MY sincere thanks to NVS Hqrs, NVS RO Hyderabad Region, NLI Rangareddy for providing me such opportunity and for making me a part of e-content development team.
• My sincere thanks to DIKSHA portal, NCERT and NROER for the useful open resource content for the development of e-content to cater the academic needs and talents of the NVS students.

​

• THE END