Handbook c2 separation techniques

Agastya International Foundation

Separation Techniques Handbook C2

“Be less curious about people and more curious about ideas.”

-Marie Curie (1867-1934)

1

Handbook C2 Separation Techniques OVERVIEW OF HANDBOOK ABL

Concept

No. Of Activities

1

Separation of mixtures containing solids Separation of mixtures containing liquids The Challenge: Using multiple techniques to separate a mixture into individual components

2 3

Page Number

2

Time (min) 40 min

5

60 min

11 – 24

1

55 min

25 - 31

1 – 10

ABL WITH REFERENCE TO STANDARD S. No

STANDARD

RELEVANT ABL

1

6

ABL 1

2

6

ABL 2

3

6

ABL 3

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2

LIST OF FIGURES, CHARTS AND WORKSHEETS S.No

Name

Page Number

Figure 1

Sieving

5

Figure 2

Separating Funnel

14

Figure 3

Set up for ABL 2.3

17

Figure 4

Set up for ABL 2.4

19

Figure 5

Set up for ABL 2.5

22

Flipchart 1

Winnowing and Threshing

31-35

Worksheet 1

Datasheet RM1.2.1

30

Worksheet 2

Learner Observation Sheet

39

Note to Instructor: All the figures in this handbook are for the instructor’s reference only. The Charts need to be printed and shown to the students during the course of the activity. Worksheets need to be printed out in advance for the students. The number of worksheets required is mentioned in the Material List.

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ABL 1 Separation of mixtures containing solids ABL 1.1

Learning Objective How do you separate substances from mixtures containing solids?

Key Messages  The handpicking method is used to separate small quantities of largesized impurities such as stone and husk from rice, wheat or pulses.  This method is based on differences in colour or appearance of the substances in the mixture. 

1.2

Why do we separate substances?

Mechanical separation methods such as threshing and winnowing are also used to separate substances.

We separate substances to:

  

Time (min) 20 min

20 min

Obtain different, but useful substances from the mixture Remove substances that are not useful Remove impure or harmful substances

 Group substances into different sizes Total Time

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40 min

4

ABL 1.1 LEARNING OBJECTIVE: How do you separate substances from mixtures containing solids?

ADVANCE PREPARATION Material List: S.No 1 2 3 4 5 6 7 8 9

Material Rice Stones Sand Sugar Black Urad dal Toor dal Sieve Flipchart-Winnowing and Threshing Data Sheet

Quantity ½ cup ½ cup ½ cup ½ cup ½ cup ½ cup 2 1 set 1 per group

Things to Do Mix the rice with the stones and store it in a cup. Similarly, mix the black urad and toor dal and keep aside.

Mix sand and sugar and keep that in a separate cup. You should have all this ready before the class begins.

Safety Precautions: Ask learners not to taste or eat any of the items provided to them.

SESSION 1.1A Link to known information/previous activity: Not Applicable Procedure: Divide the class into 6 groups. Give group 1 and 2 the mixture of toor and urad dal. Provide group 3 and 4 with the mixture of rice and stones. Give group 5 and 6 the mixture of sand and sugar. Ask all the groups to separate the individual substances from the mixtures provided to them. They can separate the substances based on their size, shape, colour, and appearance. Give them about 5 minutes to complete the activity.

The first four groups should not face any trouble in separating the individual substances. However, group 5 and 6 will not be able to separate the sand from the sugar. At the end of 5 minutes, pass around the mixture of sand and sugar to the other groups as well. Ask them if they can separate the two components.

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If the learners are unable to do so, ask them if they know any tools that can make their job easier. Now hand out the sieve to groups 5 and 6, and ask them to try and separate the sand and sugar.

UNDERSTANDING THE ACTIVITY: Leading Questions: 1.

2.

3.

4.

5.

6.

7.

8.

What do you understand by the word “substance”? Give an example.

What do you understand by the word “mixture”? Give an example.

What is separation of a mixture?

How many different substances did you find in your mixtures?

Were the sizes and shapes of the substances in the mixture different?

Would it be harder or easier to separate the substances if they were all the same size?

Can all mixtures be separated by hand?

Where else have you seen a sieve being used?

Discussion and Explanation: 1. A substance is something composed of the same kind of material throughout. Ex. A kilogram of sugar is a substance, because it contains only one kind of material – sugar. It is not a mixture.

2. A mixture is the name given to two or more substances that are mixed together, but can be separated. For example, tea is a mixture because it contains water, milk, sugar and tea leaves/ tea powder.

3. A process that converts a mixture of substances into two or more separate mixtures or into its pure substances is called separation.

4. There were two different substances in each mixture.

5. Yes, the urad and toor dal, rice and stones, and sand and sugar were all different sizes, shapes, and colors. You could easily separate the urad dal from the toor dal, and the stones from the rice by hand. This process is called Handpicking.

6. Yes, because it would be harder to see the different substances. If they were small it would be difficult to pick them up by hand. You could not separate the sand from the sugar due to the small size of the substances.

7. No, some mixtures have to be separated using different methods. We could not separate the sand and sugar by the handpicking method, but we could easily separate it using a sieve. A sieve can be used to separate substances when their sizes are very different. The fine sand will pass through the sieve, while the sugar particles will stay inside it.

8. You would have seen your mother using a sieve in the kitchen to remove lumps from maida or rava. Sieves are also used in construction sites to separate fine sand from coarse sand.

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Fig 1: Sieving

SESSION 1.1B Link to previous activity Handpicking is a method of separation that is based on the size and appearance of the substances in the mixture. But it is very difficult to separate substances when we have large quantities of the mixture.

Substances can also be separated based on other properties such as the different weights of the substances in the mixture.

Procedure Show the flipcharts with pictures of threshing (pictures 1, 2 and 3) and winnowing (pictures 4 and 5).

UNDERSTANDING THE ACTIVITY Leading questions 1. What is happening in the first three pictures?

2. What is shown in pictures 4 and 5?

Discussion and Explanation 1. Farmers are beating dried paddy stalks to separate the dried grains from them by shaking them off.

This method of separation is called threshing.Threshing used to be done only by hand but now it is done quickly by cattle or with machines.

2. Physical force is used to separate the grains from the stalks, but the husks are still present and need further separation.This is a separation technique called winnowing. The farmer takes a mixture of lighter husks and heavier grains and releases them from a height. The air carries away the lighter husk particles and they fall far away. The air cannot carry the heavier grains and they fall in a heap close to the farmer.

KEY MESSAGES:

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  

The handpicking method is used to separate small quantities of impurities of large-sized impurities such as stone and husk from rice, wheat or pulses.

This method is based on differences in colour or appearance of the substances in the mixture.

Mechanical separation methods such as threshing and winnowing are also used to separate substances.

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Small winnows are used at home to clean stones or other impurities from rice or dals. Ask your elders at home to show you how to use a winnow to clean a small quantity of rice or dal.

INTERESTING INFORMATION Wind winnowing is an agricultural method developed by ancient cultures for separating grain from chaff. It is also used to remove weevils or other pests from stored grain. In its simplest form it involves throwing the mixture into the air so that the wind blows away the lighter chaff, while the heavier grains fall back down for recovery. Techniques included using a winnowing fan (a shaped basket shaken to raise the chaff) or using a tool (a winnowing fork or shovel) on a pile of harvested grain.

Winnowing can also describe the natural removal of fine material from coarser sediment by wind or flowing water, in the same way as the agricultural separation of wheat from chaff.

WEB RESOURCES  

http://www.bbc.co.uk/bitesize/ks3/science/chemical_material_behaviour/compounds_mixtures/revision/9/ http://amrita.olabs.co.in/?sub=73&brch=2&sim=96&cnt=1

ABL 1.2 LEARNING OBJECTIVE: To understand the need for separation.

ADVANCE PREPARATION Agastya International Foundation. For Internal Circulation only.

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Material List: Not Applicable Things to Do: Not Applicable Safety Precautions: Not Applicable

SESSION Link to known information/previous activity: We have separated substances from three different mixtures in the first activity. Now let us find out why we separate substances.

Procedure: Tell the groups to retain the separated substances from the previous activity. Ask the following questions.

UNDERSTANDING THE ACTIVITY Leading Questions: 1. What are the substances that were separated?

2. Were all the substances that were separated useful?Which product was useful and which was not?

3. How was this separation helpful?

Discussion and Explanation: 1. We separated toor and urad dal, stones from rice, and sugar from sand.

2. In the first mixture, both the substances-toor dal and urad dal were useful. In the second mixture, rice was useful, but the stones were an impurity. In the third mixture, sugar was useful, while sand was an impurity.

3. All the three separations were useful. In the first one we separated two dals, and both can be eaten. From the next two mixtures, impurities that cannot be eaten and are harmful were removed.

SESSION 1.2B

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9 Distribute the data sheet RM 1.2.1, pen/pencil to each group. Ask them to discuss the reason why the mixture has been separated and tick the appropriate answer. After the activity is done, ask them to share their data sheet with class.

UNDERSTANDING THE ACTIVITY Leading questions Answer these questions while looking at the data sheet:

1.

2.

3.

4.

5.

Which mixture gave different, but useful substances?

Which mixture had substances that were not useful?

Which mixture had harmful substances?

How are some of the separated substances useful?

Can you think of any mixtures that have solid, liquid and gas substances?

Discussion and Explanation 1.

2.

3.

4.

5.

Mixture (1) – two different dals.

Mixture (2&3) –rice with stones, and sugar with sand.

Mixture (2&3) – both sand and stones are harmful Rice, dals and sugar are foods.

There are many useful mixtures found around us such as: o o o o

Oxygen (gas) + nitrogen (gas) in Air Carbon dioxide (gas) + water(liquid) in Soda Water(liquid) + dal(solid) in sambar Frozen milk (solid) + milk fat (solid) in Ice cream

KEY MESSAGES We separate substances to:

   

Obtain different, but useful substances from the mixture Remove substances that are not useful Remove impure or harmful substances Group substances into different sizes

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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ABL 2 Separation of substances from liquid mixtures Activity

Learning Objective

2.1

How can we separate mixtures of substances in a liquid?



2.2

How can we separate two liquid substances that do not mix together?



2.3

How can we separate a solid substance that is present in a liquid?



2.4

How can we get back a substance that has been dissolved in a liquid?



15 Min Evaporation is used when we want to get back a substance that has been dissolved in a liquid.

2.5

How can we separate two substances where one substance can convert directly from solid phase to vapour phase and back?



Sublimation is the process by which some substances can go directly from solid phase to the gas phase.

Sublimation can be used to separate two solid substances if one of them sublimes.

Total Time

Key Messages



Time

10 Min Sedimentation is a separation process where mixtures of two or more solid substances in a liquid can be separated when the heavier substance settles down.

10 Min Decantation is a process of separating two liquid substances that do not mix well with each other.

Filtration is a separation process 15 Min of solids from liquids either by using a filter paper or a strainer.

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10 Min

60 min

11

ABL 2.1

Time: 10 min

LEARNING OBJECTIVE - How can we separate mixtures of substances in a liquid?

Note to Instructor – These activities show that mixtures of two substances in a liquid can be separated by the sedimentation process.

ADVANCE PREPARATION Material List

1 2 3 4 5 6 7 8

Material 1 cup small stones 1 cup sand 1 cup soil 3 paper cups ½ liter water Funnel An empty 1 liter bottle Observation Sheet

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group

Things to do Not Applicable

Safety Precautions Not Applicable

SESSION ABL 2.1 Link to known information/previous activity We have seen how solids can be separated based on physical appearances, sizes and weight. Now let’s look at ways to separate solids and liquid.

Procedure Divide the class into 4 groups. Give the class all the sample materials -1 set per group. Ask the students to fill one paper cup with sand, one with soil and one with the small stones. Ask them to pour the soil, sand and small stones through the funnel into the1 liter bottle. Ask them to pour the water into the bottle until it is almost full and close the cap tightly. Next, ask them to shake the bottle thoroughly so that all the substances are mixed well. Ask them to place the bottle on the table. Leave the bottle on the table for 5 minutes and ask the students to observe the particles settling down.

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UNDERSTANDING THE ACTIVITY Leading questions 1. What happens when you shake the bottle?

2. Which substance quickly settles at the bottom? Why do you think this happens?

3. Which substance(s) settle down next? Why do you think this happens?

4. Where can you see sedimentation in your daily life?

Discussion and Explanation 1. All the substances mix together and form a mixture 2. Small stones settle down at the bottom first because they are the heaviest 3. Sand and soil settle down on top of the stones because they are lighter than the stones, but heavier than water.

4. Sedimentation is seen when we clean rice in water. The rice settles down first and the dirt particles float on the top of the water

KEY MESSAGES Sedimentation is a separation process where mixtures of two or more solid substances in a liquid can be separated when the heavier substance settles down.

LEARNING CHECK 1. Which of the following is an example of sedimentation? (Ans: b. tea) a. Mixing of milk and water. b. Tea settling at the bottom after tea and water are boiled c. Salt mixing in water and disappearing

2. Which of the following can be separated by sedimentation? (Ans. b.) a. Salt mixed with water b. Coffee powder in cold water c. Coffee decoction

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TRY IT YOURSELF Take an adult’s help and mix a teaspoon of tea powder with a cup of water and boil. Also, mix a teaspoon of coffee powder with a cup of water and boil. Pour both into a separate glass cups and observe how long it takes tea leaves and coffee powder to settle at the bottom of the cups. Which is faster? Which takes longer? Why?

INTERESTING INFORMATION In the olden days, gold diggers had to find a way to separate tiny pieces of gold from sand. They used a process called “panning”. Sand was swirled round and round with water in a pan until the lighter sand and impurities were washed out leaving the gold at the bottom.

At Kolar Gold Fields, in the olden days, a technique such as sluicing may have been used to separate gold. A device called a ‘sluice box’, a long tray with several barriers along the bottom for catching gold, was placed into a river. The water running over it separated the gold deposits from gravel and dirt.

Later, quicker methods of separation were discovered.

ABL 2.2 LEARNING OBJECTIVE –How can we separate two liquid substances that do not mix together?

Note to Instructor – These activities show that liquids that do not mix well together (immiscible liquids) can be separated by decantation.

ADVANCE PREPARATION Material List

1 2 3 4 5

Material 100 ml oil 100 ml water Separating funnel 2 plastic cups Vertical stand

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group

Things to do Set up the experiment as shown in the figure. Pour 100 ml oil in one plastic cup and 100 ml water into the other cup.

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Safety Precautions Not Applicable

SESSION ABL 2.2 Link to known information/ previous activity We saw how solid and liquid can be separated based on weight of the solid and how it settles down. How about two liquids?

Fig 2: Separating Funnel

Procedure Divide the class into 4 groups. Give the class all the sample materials -1 set per group. Ask the students to pour the oil and water into the separating funnel and close the cap tightly. Ask them to shake the funnel carefully so that both the substances are mixed well. Ask them to place the funnel in the vertical stand on the table, leaving space for a cup to fit under the funnel. Ask a student to open the knob at the bottom of the funnel slowly and collect the two separated liquids in the two cups.

UNDERSTANDING THE ACTIVITY Leading questions 1. What happens when you shake the funnel?

2. Which liquid floats on the top and which one is on the bottom? And why?

3. How do we separate the two liquids?

4. Can these liquids be separated without using the separating funnel? If yes, how?

Discussion and Explanation 1. At first, the two liquids appeared to be mixed but after some time one settled above other.

2. Water settles at the bottom because heavier substances in a mixture settle first, oil floats on top 3. The substances that form layers can be separated by using the separating funnel.

4. Yes, we can by slowly and carefully pouring (decanting) the top floating liquid into another beaker This process is known as “Decantation� We will have to leave a little bit of water in the funnel in the above experiment. If we try to remove all the lower liquid, there is a chance that some oil will get mixed with the water.

A mixture of kerosene and water can also be separated through decantation.

Decantation is also used to separate a solid that has settled at the bottom of a container with the liquid on top of it. In such cases, as we pour out the liquid on the top, we must leave a small Agastya International Foundation. For Internal Circulation only.

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amount of liquid in the container. We must also take care to prevent a small amount of the solid from flowing with the solution out of the container.

KEY MESSAGES Decantation is a process of separating two substances that do not mix well with each other.

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Make musambi or orange juice at home using a mechanical juicer or by squeezing it by hand into a glass.

Add sugar and water and mix well. Place it on a table and observe. The solid parts of the musambi or orange settle at the bottom. Now pour (decant) only the clear top part of the juice into another glass.

Could you pour only the clear part? Did some of the sediment also get decanted?

ABL 2.3

Time: 15 min

LEARNING OBJECTIVE – How can we separate a solid substance that is present in a liquid?

Note to Instructor – These activities show that mixtures of solids and liquids can be separated by the filtration process.

ADVANCE PREPARATION Material List

1 2 3 4 5

Material 1 tablespoon sand 1 tablespoon salt 1 funnel 1 piece of filter paper (to fit into the funnel) 1 beaker

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group

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16 6 7 8 9

2 beakers labeled “1” and “2” Glass rod Vertical stand 100 ml water

1 per group 1 per group 1 per group 1 per group

Things to do Attach the funnel to the vertical stand and place beaker 1 below it.

Safety Precautions Not Applicable

SESSION Link to known information/ previous activity We saw how solid liquids that do not mix can be separated by decantation. Now, let us see how we can separate a solid that is present in a liquid, but has not dissolved in the liquid.

Procedure Divide the class into 4 groups. Give the class all the sample materials -1 set per group. Ask them to add one teaspoon of sand and one teaspoon of salt in a beaker. Ask them to half fill the beaker with water and stir until the salt has dissolved.

Fig 3: Set up for 2.3

(1) Ask them to pour half of the mixture through the funnel set up into beaker 1 as shown (without filter paper) and observe. Replace beaker 1 with beaker 2.

(2)Ask them to fold a piece of filter paper into quarters and place it into the funnel. Ask them to pour the other half of the mixture through the funnel set up with filter paper and observe.

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UNDERSTANDING THE ACTIVITY Leading questions 1. What are the substances present in the mixture?

2. What happens to the sand and salt after water is poured and the mixture is stirred? Why? 3. What happens when the mixture is poured into the funnel without filter paper? Why? 4. What happens when the mixture is poured into the funnel with filter paper? Why? 5. What is collected in beaker 2 when the mixture is poured into the funnel with filter paper?

Discussion and Explanation 1. The mixture contains sand, salt and water 2. The sand slowly settles at the bottom of the beaker and the salt is not seen. The salt dissolves in water and forms a solution, while the sand does not dissolve (insoluble) 3. The mixture of sand and salt solution collects in beaker 1 4. The sand collects in the filter paper while the salt solution passes through the filter paper and collects in beaker 2 5. Filtration is the mechanical or physical process which is used for the separation of solids from liquids or gases by placing a filter through which only the liquid or gas can pass.

We use filtration in our daily lives when we make tea and separate the tea from the tea leaves using a strainer. The water we get in the tap has been filtered through filter beds to remove solid impurities.

KEY MESSAGES Filtration is a separation process of solids from liquids either by using a filter paper or a strainer.

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Mix used tea leaves (left over after tea has been made) with more water. Stir the mixture to mix well. Take a piece of paper and fit it into the tea filter. Now pour the tea and water mixture through the paper. What happens? Does the water pass through the paper? How long does it take?

INTERESTING INFORMATION Carbon filters are used to purify water by removing impurities like chlorine, sediment, volatile organic compounds, bad taste and odour from water.

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Time: 15 min

ABL 2.4

LEARNING OBJECTIVE – How can we separate a solid substance that has been dissolved in a liquid?

Note to Instructor – These activities show that mixtures of solids dissolved in liquids can be separated by the evaporation process.

ADVANCE PREPARATION Material List

1 2 3 4 5 5 6 7

Material 1 tablespoon salt 50 ml water China dish Spirit lamp Wire gauze Tripod stand Match box Tongs/holder

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group

Things to do Set up the experiment as shown.

Fig 4: Set up for 2.4 Safety Precautions Make sure that the tables for group work are arranged so that all students are safe. Keep a bucket filled with sand for proper disposal of matches. Tell students that material like paper, nylon, clothes and hair should not be brought Agastya International Foundation. For Internal Circulation only.

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19 close to the flame. Demonstrate the safe use of matches and spirit lamp. Tell the students not to push each other in their eagerness to see what is happening. Keep a bucket of water handy in case of fire related accidents.

SESSION Link to known information/ previous activity In sedimentation and filtration, the solid was separate from the liquid. That is, the solid did not dissolve in the liquid.

How do we separate something that dissolves? Like sugar solution or salt solution?

Procedure Divide the class into 4 groups. Give the class all the sample materials -1 set per group. Ask them to add one teaspoon of salt in a china dish. Ask them to pour a teaspoon of water into the china dish and stir until the salt has dissolved.

If the salt does not dissolve, ask them to add another teaspoon. (It is important to keep the solution concentrated, if not it will take a long time for the water to evaporate) Ask them to place the wire gauze on the tripod stand and carefully light the spirit lamp below the stand. Now, ask them to keep the china dish with the salt solution on the wire gauze. Tell them to observe what happens to the liquid in the china dish.

UNDERSTANDING THE ACTIVITY Leading questions 1. What happens when salt is added to water?

2. What happens when the solution is heated?

3. Where do you see this method in your daily life?

Discussion and Explanation 1. Salt dissolves in water to form salt solution. We cannot see the salt separately.

2. Water evaporates and salt is left behind 3. We see this when a little coffee or tea is left in a cup. The water evaporates and only the dark coloured tea or coffee is left behind The process we observed was liquid changing to gas or vapour. This is called vaporization.

Evaporation is a type of vaporization of a liquid that only occurs on the surface of a liquid, and it occurs at a temperature below the boiling point. The other type of vaporization is boiling, which, instead, occurs within the entire mass of the liquid.

KEY MESSAGES Evaporation is used when we want to get back substances that have been dissolved in a liquid.

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

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TRY IT YOURSELF Place a teaspoon of tea or coffee decoction in a white plate. Place the place outside in direct sunlight. What is left in the plate? Why has this happened?

INTERESTING INFORMATION Evaporation is an essential part of the water cycle. The sun energy) is responsible for the evaporation of water from oceans, lakes, moisture in the soil, and other sources of We get rain only because the water from various ponds, and rivers evaporates in the heat of the sun. This water vapour collects in the atmosphere and when the conditions right turns into rain or snow and falls back down on earth.

(solar water. lakes are

Time: 10 min

ABL 2.5 LEARNING OBJECTIVE - How can we separate two substances where one substance can convert directly from solid phase to vapour phase and back?

Note to Instructor – These activities show that mixtures of some solid substances can be separated by the sublimation process.

ADVANCE PREPARATION Material List

1 2 3 4 5 6 7 8 9 10

Material 1 tablespoon salt 1 spatula Iodine crystals 1 Petri dish China dish Spirit lamp Wire gauze Tripod stand Match box A small amount of cotton Flip chart with diagrams for simple distillation and fractional

distillation

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per class

Flipchart for Separation Techniques ABL 2.7.docx

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Things to do Mix the salt and iodine crystals in a Petri dish for each group and set it on the table. Set up the experiment as shown.

Plug the end of the funnel with cotton well, so that no vapour can escape out.

Fig 5: Set up for 2.5

Safety Precautions Tell the students that they should not touch the iodine crystals with bare hands. Make sure that the tables for group work are arranged so that all students are safe. Keep a bucket filled with sand for proper disposal of matches. Tell students that material like paper, nylon, clothes and hair should not be brought close to the flame. Demonstrate the safe use of matches and spirit lamp. Tell the students not to push each other in their eagerness to see what is happening. Keep a bucket of water handy in case of fire related accidents.

SESSION ABL 2.5 Link to known information/previous activity Not Applicable

Procedure Divide the class into 4 groups. Give the class all the sample materials -1 set per group. Ask them to add one teaspoon of salt in a china dish. Ask them to pour the iodine and salt crystals from the petri dish into the china dish placed on the experimental set-up. Ask them to place the inverted funnel over the china dish. Ask the students to light the spirit lamp and start heating the china dish. Ask them to observe the glass funnel. Ask them to turn off the spirit lamp when they observe iodine vapours released from the crystals. Ask them to let the set-up cool.

UNDERSTANDING THE ACTIVITY Leading questions 1. What is the colour of salt crystals and iodine crystals?

2. What do you observe on the funnel?

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3.

4.

5.

6.

7.

What do you observe on the dish?

What do you think has happened? Why? What is the name of this process?

Have you seen this process in your daily life?

When can this process be used?

Discussion and Explanation 1. Salt crystals are white in colour and iodine crystals are bluish purple 2. We see bluish purple iodine crystals on the funnel 3. We see salt crystals on the dish 4. Iodine has turned into vapour and formed the crystals on the funnel We have two solids here – salt and iodine crystals. Iodine crystals have a special property by which they pass from solid directly to gas without becoming liquid. So, iodine is a substance that can “sublime” 5. Sublimation is the process by which some substances can go directly from solid phase to the gas phase.

6. Yes. This process can be seen in some daily life items like camphor, naphthalene balls and odonil.

7. It can be used to separate two solids if one of them sublimes.

KEY MESSAGES  

Sublimation is the process of converting a solid directly into its vapours and condensing the vapours back into the solid state having the same composition.

Sublimation can be used to separate two solids substances if one of them sublimes.

LEARNING CHECK Ask learners to list the key things they have learnt. Guide them to the key messages listed and then put up the chart of key messages.If you have time during the class, make up a small game, quiz or match the following as a learning check. This may have to be done as part of advance preparation.

TRY IT YOURSELF Keep a piece of Camphor and place it in a place where you can observe it every day (keep it away from fire). What happens to the camphor after a few days? (the camphor becomes smaller as the days progress, because of sublimation)

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INTERESTING INFORMATION Solid air fresheners, such as Odonil, are made of chemical particles that are easily spread into the atmosphere by sublimation. This allows the particles to spread around the particular area, providing a pleasant fragrance.

WEB RESOURCES     

http://thehappyscientist.com/study-unit/sorting-sediments http://en.wikipedia.org/wiki/Placer_mining http://extension.usu.edu/files/publications/publication/NR_WQ_2012-6.pdf http://amrita.olabs.co.in/?sub=73&brch=2&sim=96&cnt=1 http://www.youtube.com/watch?v=Mrc6ld0VaYI

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ABL 3 – The Challenge: Using Multiple Techniques to Separate a Mixture into Individual Components Activity

Learning objective

Key messages

Time (min)

3.1

How can we separate a mixture of many different substances?



A mixture of many different substances can be separated using a variety of separation techniques depending on their different physical properties such as size, appearance, weight and solubility.

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30 Min

25

Time: 30 min

ABL 3.1 LEARNING OBJECTIVE –How can we separate a mixture of many different substances?

Note to Instructor – These activities show that mixtures of substances in a liquid can be separated by using a variety of separation techniques.

ADVANCE PREPARATION Material List

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21

Material 20 marbles 10-15 small stones 4 tsp rice 2 tsp sawdust 500 ml water 4 tsp salt 1 small cup sand 10 ml oil 1 tsp iron filings Plastic container with lid 2 beakers Filter Tripod stand Vertical stand Wire gauze Spirit lamp Matchbox 2 paper cups China dish Magnet

Chart on separation techniques

Number Required 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per group 1 per session (reusable) Chart on Separation techniques.docx

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Things to do Arrange the room so that the groups cannot see the other groups’ work. This is so that you can evaluate if they can use different approaches to the problem and see if they have really understood the principles of separation.

Try out this exercise once to check if the different methods and sequences can be used within the given time.

Safety Precautions Keep a bucket filled with sand for proper disposal of matches. Tell students that material like paper, nylon, clothes and hair should not be brought close to the flame. Demonstrate the safe use of matches and spirit lamp.

Tell the students not to push each other in their eagerness to see what is happening. Keep a bucket of water handy in case of fire related accidents.

SESSION Link to known information/previous activity Not Applicable

Procedure Divide the class into 4 groups. Give the groups material listed 1 through 10. Ask them to place all the material in the plastic container. Put up a list of materials 11 through 20. Tell the class that these materials are available.

Ask the students to discuss in their group and plan on how to separate the different substances. Instruct them to separate as many substances as possible within the given time and to record the separation method used by their group.

UNDERSTANDING THE ACTIVITY Leading questions 1. Could you separate all the substances?

2. What are the different methods that you used and in what order?

Discussion and Explanation 1. Yes, all the substances that were present in the mixture could be separated.

2. Enter methods used in the observations sheet attached.

Observation sheet ABL 3.1.docx

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KEY MESSAGES A mixture of many different substances can be separated using a variety of separation techniques depending on their different physical properties such as size, appearance, weight and solubility.

LEARNING CHECK Summarise the different methods with the help of the chart on separation techniques.

Learning Check 1.1 ABL 3.docx

Learning Check 2 ABL 3.docx

TRY IT YOURSELF Mix household material like maida, sand, coffee, and salt together. Use equipment available at home such as filters, sieves etc to try and separate the mixture. How many substances could you separate?

INTERESTING INFORMATION Sea water is a mixture of different types of salts and water. Most of the salt in salt water is common salt, but there are a variety of other substances also dissolved in sea water in different ratios of salt to water. It is also a homogeneous mixture or solution, since you can't actually see the various components of the mixture.

WEB RESOURCES 

http://www.youtube.com/watch?v=9Lf3jGw3_Tg

1http://www.lanascooking.com/2012/11/27/15-bean-soup/ 1http://motherhood.modernmom.com/store-dry-beans-rice-longterm-storage-7536.html

1http://www.glogster.com/jeamendoza/mixtures-solution-and-colloids-jeanette-mendoza/g-6limu14dksst2th8smlh2a0 1http://commons.wikimedia.org/wiki/File:Sand_from_Gobi_Desert.jpg 1http://www.moneycrashers.com/easy-rice-beans-recipes/

1http://3.bp.blogspot.com/-VB9bG49OIZ4/TthAyz5SlNI/AAAAAAAAAd4/70U_6fGLd2Q/s1600/salt-water-recipe.jpg

REFERENCES: 1) National Council of Educational Research and Training, Class VI, November 2012 Agastya International Foundation. For Internal Circulation only.

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28 http://www.lanascooking.com/2012/11/27/15-bean-soup/ 1http://motherhood.modernmom.com/store-dry-beans-rice-longterm-storage-7536.html 1http://www.glogster.com/jeamendoza/mixtures-solution-and-colloids-jeanette-mendoza/g-6limu14dksst2th8smlh2a0 1http://commons.wikimedia.org/wiki/File:Sand_from_Gobi_Desert.jpg 1http://www.moneycrashers.com/easy-rice-beans-recipes/

1

http://3.bp.blogspot.com/-VB9bG49OIZ4/TthAyz5SlNI/AAAAAAAAAd4/70U_6fGLd2Q/s1600/salt-water-recipe.jpg

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Data sheet RM 1.2.1

Examples of Separated Mixtures

To obtain two different, but useful substances

To remove non useful substances

To remove impurities or harmful substances

To group substances of different sizes

1.Grain separated from stalks, while harvesting 2.Tea leaves filtered after preparation of tea 3.Milk or Curd churned to separate the butter

4.Rava mixed with Iron dust 5.Coins according to value

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What do we do with the separated substances?

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Flipchart for Separation Techniques ABL 1.1 Threshing:

1

1http://tcktcktck.org/2013/01/indians-rice-threshing-photo/40366

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2

3

2http://hubpages.com/hub/Rice-Farming-in-Nepal#slide5742233 3http://www.immt.res.in/OperatedPaddyThresher.aspx

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Winnowing:

4

4http://www.flickr.com/photos/michaelfoleyphotography/5267548696/sizes/z/in/photostream/

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5

5http://oldezgold.files.wordpress.com/2012/03/winnowing_yahoo.jpg

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Flipchart for Separation Techniques ABL 2.5 Simple Distillation:

6

This method is used to separate a solid dissolved in a liquid. The apparatus to be used is shown in this diagram It consists of a small conical flask fitted with a side arm and a cork, a bent glass tube, a short piece of rubber tubing for connecting flask and tube, a test tube and a tripod stand, wire gauze and burner.

Put the mixture to be separated in the conical flask. Fill the beaker as shown with cold water and put a clean test tube into it as shown in the figure.

Now heat the mixture. Water boils, turns into vapour, comes through the tubing and condenses in the test tube surrounded by cold water. This is pure distilled water.

The solid that was dissolved in the water stays behind in the conical flask.

6http://amrita.olabs.co.in/userfiles/1/image/Simple%20distillation%20theory.png

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Fractional Distillation:

7

This method is used to separate two liquids that have different boiling points, such as water and ethanol. The liquid with the lower boiling point will boil and condense out first through the apparatus shown in the diagram.

7http://amrita.olabs.co.in/userfiles/1/image/Fractional%20distillation%20theory.png

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Chart on Separation Techniques & Properties Used No. 1 2 3 4 5 6 7 8

Separation Method Handpicking Sieving Winnowing Panning Filtration Sedimentation and decantation Sublimation Distillation

Property used for separation Difference in particle size and visual appearance Difference in particle size Difference in Weight Difference in Density Insolubility Heavy and insoluble components in mixture Only one of two solids in mixture sublimes Difference in boiling points in a mixture of two liquids; using the boiling and condensation of a liquid in a mixture of solid and liquid

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Observation Sheet ABL 3.1 Mixture Contains: Marbles, small stones, rice, sawdust, salt, sand, iron filings, oil, and water

No.

Substance to be Separated

Separation Method Used

Property used for separation

1 2 3 4 5 6 7 8 9 10

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Learning Check 1 ABL 3 Activity: 4.2. Name the separation techniques for the following figures.

Individual:

Time: 5 Min

Class:

Place:

We have looked at many different separation techniques used in our daily life. Can you name the separation technique used in each picture?

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Learning Check 2 ABL 3 Activity: 4.3 Name the method of separating mixtures you would use to solve each of the problems below. TRANSLATE sentences into local language Individual:

Time: 10 Min

Class:

Place:

_____________________________________________________________________

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