Class 6 Science Chapter 9 Methods of Separation in Everyday Life – easy notes, concepts, NCERT book solutions, important questions, worksheet and answers. Learn about different methods of separating substances such as handpicking, sieving, filtration, sedimentation, decantation, evaporation and more in simple language.
Class 6 Science
Chapter 9: Methods of Separation in Everyday Life
Easy Notes, Concepts and NCERT Book Solutions
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Chapter 9 – Easy Notes
What is a mixture?
A mixture contains two or more substances mixed together. Sometimes we need to separate these substances because we want to use one or more of them.
Why Do We Separate Substances?
1. To remove unwanted substances
Example: Removing stones from rice or pulses.
2. To obtain useful components
Example: Separating butter from curd.
Important Methods of Separation
Handpicking
Picking unwanted particles by hand when they are present in small amounts and are easy to see.
Example: Removing stones from pulses.
Threshing
Separating grains from harvested stalks by beating them.
Example: Wheat grains from stalks.
Winnowing
Separating lighter and heavier components using wind or blowing air.
Example: Separating husk from grains.
Sieving
Separating solid particles of different sizes using a sieve.
Example: Separating bran from flour.
Evaporation
Changing a liquid into vapour to separate a dissolved solid.
Example: Obtaining salt from seawater.
Sedimentation
Heavier insoluble particles settle at the bottom of a liquid.
Example: Mud settling in muddy water.
Decantation
Carefully pouring out the liquid after heavier particles have settled.
Example: Removing water from settled mud.
Filtration
Separating insoluble solid particles from a liquid using a filter.
Example: Separating tea leaves from tea.
Churning
Separating butter from curd by churning.
Magnetic Separation
Using a magnet to separate magnetic substances from non-magnetic substances.
Example: Separating iron nails from sawdust.
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Handpicking
The method of picking by hand from a mixture when two or more substances are mixed is called handpicking.
It is useful when unwanted particles are present in small quantities and can easily be picked by hand.
Examples: Removing stones from rice or pulses, removing black pepper from pulao.
Book Question
A small amount of puffed rice is mixed with chana dal. Can you think of separating the mixture by any method other than handpicking?
Threshing
Threshing is the process of separating grains from stalks by beating the stalks.
Modern method: Threshing machines called threshers can perform threshing and winnowing together.
Winnowing
Winnowing is the method of separating heavier and lighter components of a mixture by wind or blowing air.
What do you infer from Fig. 9.4? Do both the components, wheat grains and husk, fall at the same place? Which of the two components get blown away? Can the wind separate the two components?
Valli is unable to separate husk from rice in a closed room. How can you help her?
This method of separating heavier and lighter components of a mixture by wind or by blowing air is called winnowing. Have you seen any similar kind of activity being done at your home?
Sieving
Sieving is used when solid particles in a mixture have different sizes.
Fine particles pass through the holes of the sieve, while larger particles remain on the sieve.
Examples: Flour and bran, sand and pebbles.
Carefully observe a sieve. Are all the holes of the sieve the same size?
Will sieving work if the holes of the sieve are larger than the substances?
Is there any difference in the size between the particles that pass through the sieve and the particles that remain on the sieve?
Have you ever observed sieves being used at construction sites to separate pebbles and stones from the sand?
Obtaining Salt from Seawater
Seawater contains dissolved salts. When seawater is kept in shallow pits and exposed to sunlight and air, water evaporates and salt is left behind.
What is Sabarmati Ashram famous for?
Draw a poster showing Dandi March and discuss why it was organised.
Have you ever observed white patches on the dark coloured clothes you wear during hot summers? How are these patches formed?
Activity 9.2: Let us observe and create
Take water in a bowl, add salt and stir it until the salt dissolves. Put a few drops of the solution on dark paper and allow it to dry.
Do you observe some patches on the paper? What do you think is left on the paper? You can feel the presence of salt by touching the paper. Where has the water disappeared?
Find out about some water bodies in India that contain common salt. One such source is Sambhar Lake in Rajasthan.
Evaporation
Evaporation: The process in which a liquid changes into its vapour is called evaporation.
It can be used to separate a dissolved solid from a liquid.
Activity 9.3: Let us investigate
Salt solution is heated in a china dish. Water boils away and salt remains behind.
What do you observe? What is left in the china dish?
Did you get the salt back? You can feel the presence of salt in the china dish by touching the salt with your fingers.
Observe the figure. Does it answer the question? Can you name the process involved?
Is there any method through which I can get back both salt and water?
Ayurveda and Separation
In Ayurveda, some herbs and plant parts are dried in the shade. This helps excess water to evaporate and leaves behind the useful medicinal material.
Sedimentation and Decantation
Sedimentation: The process in which heavier insoluble particles settle at the bottom of a liquid.
Decantation: Carefully removing the liquid by tilting the vessel after sedimentation.
In the chapter ‘Materials Around Us’, you have studied that oil does not mix with water and forms a separate layer when left undisturbed for some time. Which method of separation would you use to separate oil and water?
Remember: Decantation may not completely separate all solid particles from a liquid. Filtration can give better separation of insoluble solids.
Filtration
Filtration is the process of separating insoluble solid particles from a liquid using a filter.
In filtration:
- The solid left on the filter is called the residue.
- The liquid passing through the filter is called the filtrate.
Activity 9.4: Let us experiment
Fold filter paper into a cone, place it inside a funnel and pour muddy water through it.
What do you observe? Do the mud particles pass through the filter paper?
How many layers of cloth do I need to use to get clear water?
Other Filtering Materials
Materials such as cotton, charcoal and sand can also be used as filters. The choice depends on the size of the particles to be removed.
Balan asks Malli if he could use a tea strainer to filter muddy water. Let us try and find out.
Activity 9.5: Let us design and create
Valli goes for a nature walk with her Dadi and collects some water from a pond in a container. She observes some unwanted substances in it. Design and create a working model of water filter using low-cost materials.
Easy idea: Use a cut plastic bottle with layers of clean cloth, sand, charcoal and small gravel. Pass muddy water slowly through it.
Important: Filtered water from a homemade model should not automatically be considered safe for drinking.
Discuss with your parents
A bowl of milk in your home has gone sour. Discuss with your parents how you can use it in another way. Also, which method of separation will you use in the process?
Churning
Churning is used to separate butter from curd.
During churning, the lighter butter collects at the top while buttermilk remains behind.
Can you name one kitchen appliance which runs on electricity that is used to prepare buttermilk?
Magnetic Separation
Substances attracted by a magnet are called magnetic substances. Iron is a common magnetic substance.
Magnetic separation is the separation of magnetic and non-magnetic substances using a magnet.
Which method of separation did the carpenter use? Recall the chapter ‘Exploring Magnets’.
Activity 9.6: Let us play
Write the following phrases on small slips of paper—
- Separating small stones from pulses.
- Churning curd to obtain butter.
- Taking out green chillies from cooked dalia (dish made of broken wheat) or poha (dish made of flattened rice).
- 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.
- Separating salt from salt solution.
Purpose: Match each situation with the most suitable separation method.
Activity 9.6 – Easy Answers
| Situation | Suitable method |
|---|---|
| Separating small stones from pulses | Handpicking |
| Churning curd to obtain butter | Churning |
| Taking out green chillies from cooked dalia or poha | Handpicking |
| Taking out seeds from watermelon | Handpicking |
| Iron nails from sawdust | Magnetic separation |
| Picking marigold flowers | Handpicking |
| Separating pebbles from sand | Sieving |
| Separating coconut pieces from rice flour | Sieving |
| Separating oil from water | Decantation |
| Separating salt from salt solution | Evaporation |
Why Do We Separate Substances?
- To separate two different useful components.
- To remove an unwanted component.
- To obtain a useful substance from a mixture.
Keywords
Summary
- Handpicking separates solid materials based on differences in size, colour and shape.
- Threshing separates grains from stalks.
- Winnowing separates lighter husk from heavier grains using wind or air.
- Sieving separates solids of different particle sizes.
- Evaporation can separate a dissolved solid from a liquid.
- Sedimentation allows heavier insoluble particles to settle.
- Decantation removes liquid by carefully tilting the vessel.
- Filtration separates insoluble solids from liquids.
- Churning extracts butter from curd.
- Magnetic separation uses a magnet to separate magnetic substances.
Let us enhance our learning
1. What purpose does handpicking serve in the process of separation?
2. Which of the following substances are commonly separated using the churning method?
3. Which factor is usually essential for the filtration?
Question 4
4. State with reason(s) whether the following statements are True [T] or False [F]. Also, correct the False statement(s).
(i) Salt can be separated from salt solution by keeping it under the Sun. [ ]
(ii) Handpicking should be used only when the quantity of one component is less. [ ]
(iii) A mixture of puffed rice and rice grains can be separated by threshing. [ ]
(iv) A mixture of mustard oil and lemon water can be separated by decantation. [ ]
(v) Sieving is used to separate a mixture of rice flour and water. [ ]
Question 5
5. Match the mixtures in Column I with their method of separation in Column II.
| Column I | Column II |
|---|---|
| (i) Gram flour mixed with black gram | (a) Handpicking |
| (ii) Chalk powder mixed with water | (b) Magnetic separation |
| (iii) Corn mixed with potatoes | (c) Decantation |
| (iv) Iron powder mixed with sawdust | (d) Sieving |
| (v) Oil mixed with water | (e) Filtration |
(i) – (d) Sieving
(ii) – (e) Filtration
(iii) – (a) Handpicking
(iv) – (b) Magnetic separation
(v) – (c) Decantation
Question 6
6. In what situations would you use decantation instead of filtration to separate solids from liquids?
Question 7
7. Can you relate the presence of nasal hair to any separation process?
Question 8
8. During the COVID-19 pandemic, all of us wore masks. Generally, what material are they made of? What is the role of these masks?
Question 9
9. A mixture containing potatoes, salt and sawdust has been given to you. Outline a stepwise procedure for separating each component from this mixture.
- Handpick the potatoes.
- Add water to the remaining salt and sawdust. Salt dissolves in water while sawdust does not.
- Filter the mixture to separate sawdust.
- Evaporate the water from the salt solution to obtain salt.
Question 10
10. Read the following story titled ‘Intelligent Leela’ and tick the most appropriate options. Provide a suitable title of your choice for the paragraph.
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/hungry, she went to the nearby pond to fetch some water/grains. After obtaining some water in the container, she noticed that the water was muddy and fit/unfit for drinking. To purify the water, she kept it for some time and then she filtered/churned the muddy water using a piece of paper/muslin cloth. Leela, then, cooled/boiled the water for about 10 minutes in a covered pan. After cooling/boiling, she filtered/churned it again and made it fit/unfit for drinking. She served this water to her father while having food, who blessed her and appreciated her efforts.
thirsty → water → unfit → filtered → muslin cloth → boiled → cooled → filtered → fit
Suitable title: Leela Purifies Water
Learning Further
Fun with parents
We are proud of our Indian heritage. 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?
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(s) and prepare a case study about the method(s) of separation he/she uses in his/her daily life. Encourage children of your community below the age of 14 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?
- Use a magnet to remove the iron nails.
- Handpick the stones and black pepper if they are easy to identify and remove.
- Filter the remaining mixture to separate sand from the salt solution.
- Evaporate the water to obtain the salt.
Reflection Steps
I observe . I wonder .
You might have wondered about questions such as—
- Which component should I separate first?
- What method of separation should I use first?
- How can we separate these components effectively?
- Will some of the components be soluble in water?
- What properties of the components can help us in their separation?
- What is the most appropriate sequence?
Activity Steps
Some possible answers to the questions which occurred in my mind are .
I performed the following methods of separation—
My findings are .
Hint: A mixture that has more than two components requires a combination of several methods of separation.
Quick Revision Chart
| Method | Property Used | Example |
|---|---|---|
| Handpicking | Size, colour, shape | Stones from pulses |
| Threshing | Grains attached to stalks | Grains from stalks |
| Winnowing | Difference in weight | Husk from grains |
| Sieving | Particle size | Bran from flour |
| Evaporation | Liquid changes to vapour | Salt from salt solution |
| Sedimentation | Heavier particles settle | Mud from water |
| Decantation | Different layers / settled solids | Oil and water |
| Filtration | Particle size and filter pores | Mud from water |
| Churning | Difference in density | Butter from curd |
| Magnetic separation | Magnetic property | Iron nails from sawdust |
One-Minute Revision
Handpicking → pick by hand
Threshing → grains from stalks
Winnowing → husk from grains
Sieving → different-sized solids
Evaporation → dissolved solid from liquid
Sedimentation → heavy particles settle
Decantation → pour off liquid
Filtration → insoluble solid from liquid
Churning → butter from curd
Magnetic separation → magnetic material using magnet
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