Methods of Separation in Everyday Life

Welcome dear students! Today we are going to learn about Methods of Separation in Everyday Life from Class 6 Science.

Let us begin with a beautiful thought from the poet Kabir. Just like winnowing makes the husk blow away while retaining the grains, similarly, sages let the virtues stay while discarding the vices. This reminds us that separating useful things from unwanted ones is a natural and important part of life.

Now, let us join Malli and his sister Valli as they get excited for their summer vacations. Their parents have planned a trip to visit relatives and friends across India. Their first stop is at their maternal grandmother Nani house in Haryana, which is surrounded by large fields. Malli and Valli see piles of grains in the courtyard. Their maternal aunt Mami and maternal uncle Mama, along with other community members, are busy separating small stones and husk from the grains by hand. Nani explains that they remove the stones so the grains are fit for cooking. Nani gives them a challenge to handpick small stones from grains with their eyes closed. The method of picking by hand from a mixture, when two or more substances are mixed, such as small stones and husk from wheat and rice is called handpicking. It is done on the basis of differences in size, colour and shape of the particles. If the particles to be removed are present in small quantities and can easily be picked by hand, handpicking proves to be a convenient method.

[CHECKPOINT]

At lunch, Malli is served vegetable pulao. He separates whole black peppers from the pulao and places them on his plate. Figure nine point one clearly illustrates this handpicking method, showing Malli picking out the black peppers. Valli playfully calls this handpicking. Later, Mama takes them to the fields where they see harvested wheat stalks. Some are spread in the sun to dry. Farmers are beating the stalks on a large wooden log. Figure nine point two shows this process of threshing. Mama explains they are beating the stalks to separate the grains. This process of separating grains from the stalks is known as threshing. Farmers often sing folk songs while working hard. You can explore folk songs of your region and try to sing along with your friends.

The separated grains get mixed with piles of husk. Valli wonders if farmers will handpick grains from so much husk and how long it would take. Let us perform Activity nine point one to find out. Take a handful of roasted peanuts and rub them between your palms. You will see the skins come off. Is it possible to separate the removed skin and the peanuts? Now, try blowing on the mixture. What do you observe? You will observe that blowing air separates the heavier peanuts from the lighter skins. The lighter peanut skins are blown away. You observe that blowing air separates the heavier and the lighter components. How do farmers separate so many grains from husk? Traditionally, a soop, which is a bamboo tray, is used for separating heavier and lighter components of a mixture. Figure nine point three shows this traditional bamboo tray. Next day, their Nana takes them to the fields. They see a farmer on a raised platform moving a bamboo tray containing threshed wheat grains in the direction of air or wind, as shown in Figure nine point four. The lighter husk gets blown away while the heavier grains fall down. This method of separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing. Have you seen similar activity at home?

[CHECKPOINT]

More to know: Technological developments have resulted in developing of threshing machines called threshers. These machines are used for separating grains from the stalks and husk. They perform both the tasks of threshing and winnowing simultaneously.

Next day, Malli and Valli board a train to Ahmedabad. Before leaving, Valli asks Mami to prepare sweet Indian bread. Valli offers to knead wheat flour. Mami says they must first remove bran that may be present in the flour. Mami explains they use a sieve for this purpose. Figure nine point five shows sieving in action. Sieving allows the fine flour particles to pass through the holes of the sieve. The bigger particles such as bran and small stones remain on the sieve. Carefully observe a sieve. Not all holes are the same size. Sieving will not work if the holes are larger than the substances. There is a clear difference in size between particles that pass through and those that remain. Sieving is used when components of a solid-solid mixture have different sizes. The process of separating solids from a mixture based on variations in particle size using a sieve is called sieving.

Upon reaching Ahmedabad, they visit Sabarmati Ashram and learn about the Namak Satyagrah, also known as the Dandi March. More to do! What is Sabarmati Ashram famous for? Draw a poster showing the Dandi March and discuss why it was organised. You should find out that Sabarmati Ashram was Mahatma Gandhi's home and the starting point of the Dandi March, a famous protest against the salt tax. Malli asks where common salt is obtained from. Ghanshyam bhai replies it comes from seawater. Seawater is a mixture of salts and some other substances dissolved in water. To obtain salt, seawater is kept in shallow pits and exposed to sunlight and air. Figure nine point six illustrates this process of obtaining salt from seawater. In a few days, the water evaporates completely, leaving behind the solid mixture. Common salt is then obtained from this mixture by further purification. Find out about some water bodies in India that contain common salt. One such source is Sambhar Lake in Rajasthan.

[CHECKPOINT]

Let us explore how salt can be separated from a salt solution through Activity nine point two. Have you ever observed white patches on dark coloured clothes during hot summers? These patches form from evaporated sweat containing salt. Take a bowl and fill it half with water. Add two to three teaspoons of salt and stir till it dissolves. Take a small piece of black or dark coloured thick paper and spread a few drops of the salt solution on it. You can create art with it. Figure nine point seven shows the paper before drying, after drying, and an art piece created with the solution. Allow it to dry and observe. You will see white patches on the paper. The salt is left on the paper, which you can feel by touching. The water has disappeared into the air through evaporation.

In the traditional Indian system of holistic health and medicine called Ayurveda, the herbs or parts of plants are prescribed as remedies. These ingredients like roots, leaves, flowers or seeds of various medicinal plants are often dried in the shade. This practice facilitates the evaporation of excess water, leaving behind the important part of the medicine.

Now, let us probe further with Activity nine point three. This activity may be demonstrated by the teacher. Take some salt solution in a china dish. If a china dish is not available, another suitable vessel may be used. Heat and let the water boil away as shown in Figure nine point eight. Allow the china dish to cool down. You will observe solid salt left in the dish. You can feel the presence of salt by touching it with your fingers. Caution: Be careful while heating the china dish. Did you get the salt back? Yes. To get back both salt and water, you would need to collect the water vapour and condense it back to liquid, a process called condensation.

[CHECKPOINT]

It is time for Malli and Valli to visit their paternal grandparents Dada and Dadi in Puducherry. They meet their friend Balan. Dada prepares tea and shares tips. He explains that after making tea, tea leaves are removed with a strainer. If no strainer is available, you can leave the vessel undisturbed and gently pour the tea into a cup. Figure nine point nine demonstrates this decantation process. The tea leaves settle at the bottom. The process of settling down of heavier insoluble component at the bottom of a liquid is called sedimentation. When the water, or liquid, is removed by tilting the vessel, the process is called decantation. Decantation is also used in washing and cleaning of rice and pulses. Oil does not mix with water and forms a separate layer. You can separate oil and water by decantation. However, decantation does not completely separate all tea leaves. Dada then pours tea through a tea strainer, collecting all leaves. This process of separating tea leaves from tea is called filtration. Filtration can be used to separate insoluble solid components from a liquid.

Balan asks if a tea strainer can filter muddy water. Dada says yes, but a piece of cloth works better because it has very small holes or pores between woven threads. These pores act as a filter. Ancient people used this. For even finer filtration, a filter paper with very fine pores is used.

[CHECKPOINT]

Let us try Activity nine point four. Try to fold the filter paper yourself and make a cone. Figure nine point ten shows the folding steps: one fold, two folds, and finally forming a cone. Place it inside a funnel kept on a conical flask and pour muddy water into it, as shown in Figure nine point eleven. The setup shows a tripod stand holding the funnel, with a conical flask below to collect the liquid. You will observe that mud particles do not pass through the filter paper. The water collected in the flask is clear. You will get mud as a residue on the filter paper and clear water as filtrate in the conical flask.

More to know: Other than filter paper, many materials such as cotton, charcoal, and sand can be used as filters. The choice of filter depends upon the size of the particles of the materials to be removed.

Activity nine point five invites you to design and create a working model of a water filter using low cost materials, after collecting pond water and observing unwanted substances.

Did you know? Tea bags were initially made of soft cloth, like silk, because it could hold the tea leaves and let water pass through. Silk was strong and did not fall apart when it touched hot water. Later, people started using gauze or muslin. Eventually they began using filter paper, which is what most tea bags are made of today.

[CHECKPOINT]

Malli and Valli go on a boat ride with Dada and his fisherman friend Otukkam. They see a fishing net where water drains through the mesh, similar to filtration. They also see plastic bags, broken bottles, a fish with a straw in its mouth, and food wrappers trapped in the net. This highlights river and ocean pollution. Let us raise awareness by composing a poem: Piece of plastic in my neck, as in pain I cry, Koilas, Koilas, where are you dear? Papa fish cries and Mama fish has tears. Aware of the harm, yet they let it flow, Koilas faintly hears mother sorrow. Stop plastic pollution at source, rivers are our huge resource. Discuss with your parents how to use sour milk. You can separate the solid curd from the liquid whey by straining or filtration.

Malli and Valli travel to Madhya Pradesh. They drink buttermilk at a roadside eatery. A painting shows a lady churning curd using a big churner to separate butter. In this process, the butter being lighter floats at the top, while the buttermilk is left behind. Can you name one kitchen appliance which runs on electricity that is used to prepare buttermilk? It is the electric mixer or blender.

[CHECKPOINT]

Their final destination is Shillong, Meghalaya. They notice a carpenter who drops iron nails in sawdust. The carpenter starts handpicking. The children suggest using a magnet. When moved through the sawdust, the magnet attracts all the nails. Figure nine point twelve illustrates this magnetic separation. The substances which are attracted towards a magnet are called magnetic substances. Iron is a common example of a magnetic substance. Separation of magnetic and non-magnetic substances by using a magnet is called magnetic separation.

More to know: Nowadays, recyclers use magnets to separate iron articles from a heap of waste. In many industries, the waste material often contains scrap iron. This is separated from the heap of waste materials using magnets fitted to a crane. The scrap iron can be recycled and reused.

Activity nine point six asks you to write phrases on slips of paper: Separating small stones from pulses, churning curd to obtain butter, taking out green chillies from cooked dalia or poha, taking out seeds from watermelon, sorting piles of sawdust and iron nails from a mixed heap of building material, picking marigold flowers from a heap of other flowers to make a garland, separating pebbles from sand, separating coconut pieces from rice flour, separating oil from water, and separating salt from salt solution. Take two baskets representing two purposes: to remove any one of the components that is not useful, and to separate two different but useful components. Form two teams and sort the slips correctly. This helps assess your understanding of why we separate substances.

[CHECKPOINT]

Let us review the keywords: Churning, Decantation, Evaporation, Filtration, Handpicking, Magnetic separation, Mixture, Sedimentation, Sieving, Threshing, Winnowing.

Now, let us look at the summary key points. Handpicking is used for separating solid materials on the basis of differences in size, colour and shape from a mixture. The process in which the stalks are beaten to separate grains from them is called threshing. The method of separating lighter husk from heavier grains by wind or blowing air is called winnowing. The process of separating solids from a mixture based on variations in particle size using a sieve is called sieving. Evaporation is the process in which a liquid gets converted into its vapour. It can be used to separate a solid dissolved in a liquid. The process of settling down of heavier insoluble component at the bottom of a liquid is called sedimentation. When the liquid is removed by tilting the vessel, the process is called decantation. Filtration can be used to separate insoluble solid components from a liquid. Churning is used to extract butter from curd. Separation of magnetic and non-magnetic substances by using a magnet is called magnetic separation.

Let us play the Wise Fish game. Prepare a fishing rod with eco-friendly materials. Tie a thread to a rod and a magnet to the free end. Tank one has red cardboard fish representing methods: Filtration, Decantation, Condensation, Handpicking, Churning, Evaporation, Winnowing, Sedimentation, Sieving, Threshing, Magnetic separation. Tank two has blue cardboard slips attached to iron clips representing properties: difference in magnetic properties, difference in size of solid particles, heavier particles settle down, mixture of oil and water, extract butter from curd, separate salt from seawater, beating stalks to remove grains, conversion of water vapour into its liquid state, insoluble particles get filtered as residue, larger particles are handpicked, lighter component of mixture is separated by blowing air. Fish out a red fish first, then match it with the correct blue slip. Watch your friends to see if they match correctly.

[CHECKPOINT]

Now, let us enhance our learning by answering the exercise questions completely.

Question one: What purpose does handpicking serve in the process of separation? The correct option is two, Sorting. Handpicking sorts and removes unwanted components like stones or husk based on visible differences.

Question two: Which of the following substances are commonly separated using the churning method? The correct option is three, Cream from milk. Churning separates lighter butter or cream from heavier buttermilk.

Question three: Which factor is usually essential for the filtration? The correct option is three, Pore size. The size of the pores in the filter determines which particles pass through and which are retained.

Question four: State with reasons whether the following statements are True or False, and correct the false ones. Statement one: Salt can be separated from salt solution by keeping it under the Sun. True. The sun provides heat for evaporation, leaving salt behind. However, as shown in the seawater to salt process, it works best when the solution is kept in shallow containers exposed to sunlight and air for several days. Statement two: Handpicking should be used only when the quantity of one component is less. True. It is practical only when unwanted particles are few and easily visible. Statement three: A mixture of puffed rice and rice grains can be separated by threshing. False. Threshing separates grains from stalks. Puffed rice and rice grains should be separated by winnowing or sieving based on size and weight. Statement four: A mixture of mustard oil and lemon water can be separated by decantation. True. Just as oil does not mix with water, it does not mix with lemon water and forms a separate layer when left undisturbed, allowing the top oil layer to be decanted. Statement five: Sieving is used to separate a mixture of rice flour and water. False. Sieving separates dry solids of different sizes. Rice flour and water form a suspension or paste and should be separated by filtration or evaporation.

[CHECKPOINT]

Question five: Match the mixtures in Column one with their method of separation in Column two. Gram flour mixed with black gram matches with d, Sieving. Chalk powder mixed with water matches with e, Filtration. Corn mixed with potatoes matches with a, Handpicking. Iron powder mixed with sawdust matches with b, Magnetic separation. Oil mixed with water matches with c, Decantation.

Question six: In what situations would you use decantation instead of filtration to separate solids from liquids? You would use decantation when the solid particles are heavy, have settled completely at the bottom, and you want to quickly remove the clear liquid without waiting for filtration. It is faster and suitable for large volumes where the solid does not need to be completely dry.

Question seven: Can you relate the presence of nasal hair to any separation process? Yes, nasal hair acts like a natural filter. It traps dust, pollen, and other large airborne particles from the air we breathe, similar to how a sieve or filter paper traps solid particles.

Question eight: During the COVID nineteen pandemic, all of us wore masks. Generally, what material are they made of? What is the role of these masks? Masks are generally made of multiple layers of non woven fabric, cotton, or polypropylene. Their role is to act as a filter, trapping respiratory droplets, dust, and pathogens, preventing them from entering our nose and mouth, similar to filtration.

[CHECKPOINT]

Question nine: A mixture containing potatoes, salt and sawdust has been given to you. Outline a stepwise procedure for separating each component from this mixture. Step one: Use handpicking to remove the large potato pieces from the mixture. Step two: Add water to the remaining mixture of salt and sawdust. Stir well. The salt will dissolve in water, while the sawdust will float or remain suspended. Step three: Use filtration to separate the sawdust. The sawdust will remain as residue on the filter paper, and the salt solution will pass through as filtrate. Step four: Heat the salt solution in a china dish. The water will evaporate, leaving behind solid salt. Alternatively, you can use evaporation to recover the salt.

Question ten: Read the story titled Intelligent Leela and tick the most appropriate options. Provide a suitable title. Leela was working in the farm with her father when she realised that they left their drinking water at home. Before her father felt thirsty, she went to the nearby pond to fetch some water. After obtaining some water in the container, she noticed that the water was muddy and unfit for drinking. To purify the water, she kept it for some time and then she filtered the muddy water using a piece of muslin cloth. Leela, then, boiled the water for about ten minutes in a covered pan. After cooling, she filtered it again and made it fit for drinking. She served this water to her father while having food, who blessed her and appreciated her efforts. You should create your own suitable title for this paragraph. Examples might include titles that highlight Leela's intelligence or the water purification process, such as Leela's Smart Solution or The Clever Water Purification.

[CHECKPOINT]

Now, let us explore the learning further activities. Fun with parents: Under supervision of your elders, try to prepare some herbal remedies using various parts of plants, for example tulsi kadha. Which methods of separation will you use while preparing herbal kadha? You will use filtration or straining to separate the solid herbs and leaves from the liquid decoction. You may also use decantation if the solids settle. Stage play: Imagine you and your friend are Malli and Valli. Write dialogues of a play presenting their entire Bharat ki Yatra, highlighting the different methods of separation of substances that they observed. Enact the play in your school assembly. Group activity: Observe and list separation methods you employed and noticed in your surroundings throughout a week. Explain the reasons behind using these methods and compile the ones you utilised or observed the most. Compare your observations with your group members. Be a stalwart of your community: Interview a ragpicker or ragpickers and prepare a case study about the method or methods of separation he or she uses in his or her daily life. Encourage children of your community below the age of fourteen to join a neighbourhood school. Be a reporter: Gather newspaper clippings and articles related to various methods of separation implemented in your society, such as in agricultural fields or at construction sites. Conduct interviews with local farmers to explore the latest agricultural separation methods that they use. Think like a scientist: You are provided with a mixture of iron nails, sand, black pepper, stones, common salt and water. Which steps will you follow to separate each component of a mixture? I observe a complex mixture of solids and liquid. I wonder which component should I separate first. I will first use a magnet for magnetic separation to remove the iron nails. Next, I will use a sieve or handpicking to remove the large stones. Then, I will add water to dissolve the salt. The sand and black pepper will not dissolve. I will use filtration to separate the sand and black pepper mixture from the salt solution. To separate sand and black pepper, I will add more water. Black pepper floats while sand sinks. I will decant the water with black pepper, then filter to collect black pepper, and dry the sand. Finally, I will evaporate the salt solution to recover the common salt. My findings are that a mixture with more than two components requires a combination of several methods of separation, applied in a logical sequence based on the physical properties of each component.

[CHECKPOINT]

We have covered every method of separation discussed in this chapter, from handpicking and threshing to winnowing, sieving, evaporation, sedimentation, decantation, filtration, churning, and magnetic separation. Remember to practice these concepts by observing them in your daily life. Understanding how to separate mixtures helps us in cooking, cleaning, agriculture, and even in keeping our environment safe.

Thank you for listening! Keep revising and practicing. Goodbye! [CHAPTER_COMPLETE]