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CLASS
VIVICBSE-i
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
SCIENCE
SEPARATION OF MIXTURES
SCIENCESCIENCE
CHEMISTRY CHEMISTRY CHEMISTRY CHEMISTRY
UNIT-6
The CBSE-International is grateful for permission to reproduce and/or
translate copyright material used in this publication. The
acknowledgements have been included wherever appropriate and
sources from where the material may be taken are duly mentioned.
In case any thing has been missed out, the Board will be pleased to
rectify the error at the earliest possible opportunity.
All Rights of these documents are reserved. No part of this
publication may be reproduced, printed or transmitted in any form
without the prior permission of the CBSE-i. This material is meant for
the use of schools who are a part of the CBSE-International only.
UNIT-6
SCIENCE
SEPARATION OF MIXTURES
SCIENCESCIENCE
CHEMISTRY CHEMISTRY CHEMISTRY CHEMISTRY
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
CBSE-i
CLASS - VI
CONTENTPREFACE
ACKNOWLEDGMENT
SYLLABUS COVERAGE 2
SCOPE DOCUMENT 3
CROSS CURRICULAR LINKS
MATRIX 4
RESOURCES 6
TEACHER NOTE (TN) 7
TEACHER STUDENT SUPPORT MATERIAL (TSSM) 17
1. INTRODUCTION 18
2. MIXTURES 19
(i) ITS TYPES
ACTIVITY No. 1 21
WORKSHEET No. 1 23
(ii) CHARACTERISTICS OF MIXTURES 24
3. NEED FOR SEPARATION OF MIXTURE 24
FORMATIVE ASSESSMENT - 1 26
4. METHODS TO SEPARATE MIXTURES
(A) SOLID - SOLID MIXTURES 27
(i) WINNOWING 27
(ii) SIEVING 28
(iii) HANDPICKING 28
ACTIVITY - 2A 30
ACTIVITY - 2B 31
v
v
v
v
v
v
v
•
•
•
•
•
•
•
•
•
•
•
•
•
•
•
ACTIVITY - 2C 32
ACTIVITY - 2D 33
WORKSHEET - 2 34
(B) SOLID - LIQUID MIXTURES 35
(i) SEDIMENTATION AND DECANTATION 35
ACTIVITY - 3A 36
(ii) FILTERATION 37
ACTIVITY - 3B 38
(iii) EVAPORATION 39
ACTIVITY - 3C 40
(iv) CENTRIFUGATION 40
ACTIVITY - 3D 41
WORKSHEET - 3 42
FORMATIVE ASSESSMENT - 2 43
(C)LIQUID - LIQUID MIXTURES 43
ACTIVITY - 4 44
WORKSHEET - 4 45
SUMMATIVE ASSESSMENT 46
KEY NOTES 50
SUMMARY 51
RUBRIC : ASSESSMENT FOR LEARNING 52
•
•
SEPARATION OF
MIXTURES
1
2
SYLLABUS COVERAGE
Separation of MixturesS
Y
L
L
A
B
U
S
v
v
v
v
v
v
Introduction
Mixtures
Types of mixtures
Separation of solid mixtures
Separation of solid - liquid mixtures
Separation of liquid -liquid mixtures
3
SCOPE DOCUMENT
INTENDED LEARNING OUTCOMES:
At the end of this unit the students would be able to-
Understand what is a mixture and when do we need to separate different
components of mixtures.
List the various ways by which the components of a mixture can be separated.
Use appropriate vocabulary to describe these methods.
Reason out the principle behind these methods of separation. Intelligent use of
understanding must be directed to save 4Es, Energy, effort, environment and
Economy.
Identify the ways of separating;
a) solid –solid mixtures,
b) solid- liquid mixture,
c) liquid-liquid mixture.
CROSS- CURRICULAR LINKS
PHYSICS – Separation of mixtures iron (scrap) with the help of magnet.
English – Enriches vocabulary, improvement in reading skill.
ICT – Power Point Presentations and Videos, allows open exploration and supports
learners to work more independently.
4
MATRIX
Content/ Concepts Intended Learning Skills
What are mixtures?
Characteristics of a
mixture.
Different type of mixtures.
Homogenous
Heterogeneous
To familiarize the students with the
examples of mixture used in our
daily life.
Students would be able to identity
different examples of mixtures used
in daily life.
Observation &
recording
Listing
Curiosity to know
more about
Mixtures.
Need to separate
components of a mixture.
Processes;
to separate by property.
To separate a solid – solid mixture
To separate a mixture of colorful
beads of different sizes/ coins
of different denominations)
.(handpicking)
To separate a mixture of small stones
and bits of paper (winnowing)
To separate a mixture of wheat flour
and rice grains. (sieving)
To separate a magnetic component
from a mixture containing non-
magnetic components.
Manually separate mixtures made
from different components based on
colour, size and property.
think and (act),use
of
Psychomotor
skill. coordinated
handling of
apparatus
Solid- solid mixtures. different ways to separate complex Process skills.
5
Winnowing
Sieving
Hand picking
Solid-liquid
mixtures.
Sedimentation
Decantation
Filtration
Evaporation.
Centrifugation
mixtures in which components are
relatively less easy to separate
manually.
Different techniques/ processes to
separate solid liquid mixtures:
insoluble solid from the liquid by the
process of sedimentation and
decantation.
an insoluble solid from the liquid
completely in the lab. by the process
of filtration.
a soluble solid (salt) from a liquid in
the lab by the process of evaporation
a mixture of cream and milk by the
process of centrifugation (churning)
Observation &
Recording,
Accuracy
Liquid-liquid mixture Method to separate a liquid – liquid
mixture using separating funnel
e.g. a mixture of oil and water.
Accuracy in
measurement and
observation
6
Resources
NAME
VIDEOCLIPS/WEB LINK/POWERPOINT
Video clip1
PowerPoint
http://www.wiziq.com/tutorial/38393-Separation-of-Substances
Videoclip-2 http://www.youtube.com/watch?v=n3Usa6mOkhM
Separation of solid- solid mixture
ACTIVITY 2d
PowerPoint
Presentation-1
Separation of Solid – liquid mixture
Introduction to the topic- filtration
Web link
Animation
filtration through a animation created by Joseph Clark.
http://www.saskschools.ca/curr_content/science10/unita/redo
n17.html
Videoclip-3 http://www.youtube.com/watch?v=5rZ1JUMSmDk
(churning) ACTIVITY 3d
PowerPoint
Presentation-2
Separation of liquid – liquid mixture
Introduction to the topic
Videoclip-4 http://www.youtube.com/watch?v=vcwfhDhLiQU
Separation of liquid – liquid mixture
ACTIVITY 4
Web link http://www.slideshare.net/teocc/online-separation-techniques-
1662272
Concluding the chapter recap.
7
Teacher note (TN)
Separation of Mixtures
Dear Teacher you would have observed that ‘the nature of Science’ is not appearing the
this unit.Yes! this step is taken in awareness that by three exposures , the idea would
have seaped enough and is serving as a background for development of a rational
outlook. CBSE(i), in spirit, works to empower both teachers and students through
learning interaction.
In this unit there is an emphasis on hands-on-activities organized as introduction or to
develop the topics. Through this unit the learner will be able to:
Define the term ‘mixture’
Identify type of mixtures
Appreciate the need to separate mixtures
Understand various methods of separation of mixtures
Apply their knowledge to derive combination of methods of separation
Relate what they learn with their day-to-day experiences.
Have value added learning.
The definition of a conceptual understanding is far more valuable than cramming
definitions. However, definitions may be written by learners in there own words after
the concept is discussed. Mixture must not be the main focus but should be derived at a
later stage. As a teacher always keep in their mind that any lesson that starts with
definitions or points to learn will make students lose interest and hence will make it
difficult for them to comprehend the concept. It is therefore suggested that you should
not start the unit by listing on the board the types of mixtures and the types of methods
of separation and so on.
8
The definition of the concept / term ‘mixture’ must be be arrived at a( later) stage
after the concept has been explored, thrashed out and assimilated with the relevant
examples elicited from the learners. This means care must be taken to warm up the
learners adequately at the start . Naturally, you would have to invest time in
planning the class interactions systematically as some of you might be doing. Still it
is suggested that as a pre task you find as many examples as possible. The advantage
of doing so is that when learners share their examples you would be ready to handle
them deftly to connect to the specific topic and benefit the whole class.
On the other hand, some of you may wonder why to waste human resource in asking
students for evidence and keeping it handy with oneself. Does it mean a ritualistic
practice with no trust in the capability of the learners! Infact, contrary to this view ,
such an exercise is primarily based on trust in the learners potential to observe and
express their experience- based examples in class. As a teacher it would be a rich,
diverse and authentic resource for you to decide, reorganize and even revise your
plan or strategy.
Based on your experience as a teacher you would appreciate that any lesson that
directly starts with definitions or points to learn will make students lose interest and
hence will make it not only a difficult process but may be doubtful to comprehend the
concept . You could start the unit by way of brain storming. This apparently
unstructured and unthreatening participation evoked from the learners would be
effective only when you have already reflected on the dimension of perspective
building through teaching – learning of this unit. Therefore, you may frame questions
to stimulate curiosity of the learners to know deeply and diversely about the topic. You
can choose to list responses of students about different type of mixtures and the
different methods to separate them.
You can demonstrate your acumen to organize information systematically. This is
modeling scientific process of learning. Performing the task professionally means
carefulness to display your skill to speak with modulation, work with accuracy and
9
efficiency, write legibly and in an organized way. Modern values are possible to
exchange through observed action.
Introduce the topic in the class by simple examples such as the use of sieve to separate
used tea leaves from tea. Involving the students in the discussion on why tea leaves are
separated ,probe the class to at least arrive at an understanding that the tea leaves are
not useful and are undesirable so they have to be separated. This will ensure that the
students develop reasoning ability.
Question;
Of what use are the tea leaves?
How can we use the tea leaves to get maximum benefit from them? (TN unit 3 Food and
Nutrition importance of cooking, preparing nourishing tea)
What use can be made from brewed tea leaves?,
This could be taken as an example to make the learners understand the term ‘Filtration’.
separation is a simple term which is used broadly. Filteration is a separation of specific
substances i.e. a solid from a liquid.
Introduce few mixture types to them while obtaining the answers from them on what
are the components of each mixture e.g. in case of prepared Tea (mixture) the
components are tea leaves, sugar, milk & water. This mixture is a mixture of liquid and
solid. Next you may organize the information on priority basis i.e. tea and water. sugar,
milk, extra flavors would be the accessories to lend taste to the tea. The essential
components of hot and ice tea can be discussed. Here, You have temporarily
deconditioned that tea is served and consumed when only it is hot.
The encouraged learners should be asked to give more examples of such mixtures. This
can be done by the starter activity of students standing in a circle tossing the ball and
naming a mixture. Encouragement should be provided at any cost to nurture the self
worth of the child it the students if they
10
Take care that while the lesson is being developed the students are not directed to the
teacher approved examples only. You, as a human being, would naturally appreciate
when learners quote your suggested information but as a professional your success lies
in enabling the learners rather than truncating their thinking to what you know. Your
readiness to grow in knowledge would impact healthy learning attitude. Save yourself
from prejudice of wanting students to agree with your answer unquestioningly. simply
follow the guideline of moving from known to unknown. This will help the you to
make the lesson more interesting when the students are taking the lesson forward
themselves.
You can take up each type of mixture named by the students in a sequence for further
study.
Step I You could prepare a concept web based on the related terms used
commonly and their scientific expressions as a starter. This could work as
an overview.
Step II Organize a route map based on your rapport with the learners and learners
style of learning. A heterogenuous class can be a real professional challenge
for a teacher to deal with.
One way could be to include:
Defining what is a mixture.
The type of mixtures.
Solid-Solid mixture
Solid-Liquid mixture
Solid-Gas mixture
Liquid-Liquid mixture
Liquid-Gas mixture
Gas-Gas mixture
Methods of separation of mixture
Need to separate the mixtures
Vocabulary development
11
The concept of filtration can be further strengthened by using different examples of
mixtures depending on the size of the impurities (undesirable substances). The
demonstration of filtration process by using filter paper can be demonstrated.
Corollary can then is drawn by using the technique of question answers, suggest some
questions. It is essential to clarify the difference between the quantity (amount) and the
size of each particle.
To arrive at the understanding that filtration process is used to separate a solid from a
liquid. You need alertness to enable learners to derive the conclusion that filtration
process can be used when the following conditions are fulfilled, this will depend on the
size of the particles of impurities. Separation does not necessarily involve impure
particles.
You could attempt to be a resourceful facilitator so that the learners are able to derive
the conclusion about filtration as a process that will depend on the size of the particles
of the impurity. For this, variables could be changed and its effect observed. Evidence
based learning can become a source of careful observation.
For an extended learning the size of pores of the sieve or filter paper best suited for
different sized particles must be the focus. It will be quite challenging for the teacher to
explore if the students can relate their knowledge skillfully to the size of the particles
(undesirable substances) and the type of filter paper to be used to separate undesirable
substances from the mixtures.
For extended learning discuss examples of air conditioner, vehicles where filter is used
to keep away the particulate – material from blocking the gadget from working could
also be discussed as per the requirement of the class and the use of water filter for
purifying the water.
Cash occasions wherein through exchange of ideas, perspective building of the
learners is linked . You could ask the students to find out if in earlier time impurities
were found in things of daily use like water and food? In what ways did people get
12
rid of it ? what did they use to minimize the impurity? How did development of
technology assist in purifying the essential food? Is technology based machine or
instrument enough to ensure a life without impurity? Has human agency any role to
play in creating an environment free from impurity? Suggest simple ways to do it
that can be practiced by us daily.
..
Discuss the concept of impurity in mixtures, its relation to the economic gain at the
expense of ethical aspect. Communicate about the thought of expenditure incurred
when health gets affected by impurities. Discuss the reason why people
indiscriminately use impurities? How to stop this attitude? Such exercises will trigger
the students to contribute more meaningfully to the class room discussion.
Planning is a prerequisite for effective outcome. For showing different types of
mixtures the teacher should plan different type for each type of activity.
The demonstration of solid–solid mixture may be done by mixing two substances such
as small rice grains in flour. This should be co-related with the method of separation
such as hand picking. Through some video clipping ‘winnowing’ as a method of
separation could be shown. It will arouse the curiosity of the students and they will
think about the kind of substances that can be removed by this method.
You could then help the students differentiate among the types of mixtures. spend
some time on these activities as this is the formative stage of conceptual unfolding. The
students should now be able to understand the different methods of separation are used
for different types of mixtures .when they start suggesting ways to separate different
specific mixtures know it as the application of the newly acquired concept mixtures,
The learners would further summarize what they studied about solid-solid mixture.
(rice & flour) and solid-liquid mixture (tea). The method of separation used for these
two types is handpicking, winnowing and filtration (use of sieve).
13
Vocabulary development must go hand in hand while explaining the terms such as
solute, solvent, filtrate, impurities, un-desirable substances etc.
Encouraging and guiding the learners to do the comparison of filtration method of
separation with sedimentation and decantation could be achieved either by
demonstrating these processes or enabling the learners analytic and psychomotor skills.
You could employ different methods such as oral/group work/presentations so that
they are able to list the types of mixtures that can be separated by these. SPELL OUT the
steps to make the group activity challenging, interesting and conceptuallty enriching.
Help the students to go beyond what they have studied i.e. solid-solid and solid-liquid
mixtures. To enhance the observation skills the teacher could ask the students what
they observe after showing them a mixture of lime and water and by opening a cold
drink bottle. What happens when a cold drink bottle is opened? The gas escapes from
the liquid. She will be able to extract the answers from the students on the components
of mixtures in case of lime water and a cold drink.
To further develop their thinking skills she could elicit from the students that lime
water is liquid-liquid mixture and a cold drink is liquid-gas mixture. This will arouse
the curiosity of the students and they will be able to give more examples of these types
of mixtures.
Take the example of milk and water mixture and give the learners a chance to tell how
pure milk can be obtained from a mixture of milk and water. The teacher can extract the
answer that by evaporation method water will evaporate and pure milk will remain.
Does it have any impact on the quality of milk? If the milkman gives ½ liter of milk mixed with
water will the quantity of milk reduce after the evaporation of water from this mixture?
If their answer is yes! It reduces. Relate it to how milkman cheats himself .when he charges for
an amount, say,½ litre of milk but gives less than what is agreed upon. He mistakes to be clever
in earning more .actually he is socially doing an irresponsible act as we already studied in unit
14
on food and nutrition about the importance of nutritious food for a healthy life. From a scientific
perspective he is compromising with the quality of food. You could now introduce the term
adulteration as an extended learning. Create an activity to sharpen the observation of the
students on what they eat. Is it their responsibility to take care of what they consume?
Similarly connect the same by discussing about the impurities added to the pulses, rice
etc. by the shopkeeper for their myopic understanding of profit. The students can be
given some project work on the role of students to increase awareness about these
issues.
Sometimes these adulterations while giving financial benefit to the shopkeepers may be
hazardous to the health of a person. Such news is often published in the newspaper.
The students may be asked to collect some relevant news from newspaper and paste
these in their notebooks. Ask the students to mock talk to the shopkeeper or the vendor
who plays with health of others and share with others.
From the story of ‘Namak Andolan’ by Gandhiji, help learners apply their knowledge
on how water evaporates when heated or kept in a container under the sun. The
concept of evaporation can hence be re-enforced.
Tell them about how salt was obtained from sea and relate it with the significance of
this salt movement by Gandhiji. Inter-disciplinary approach must be kept on mind.
This will not only make the topic interesting but will also help the students understand
the significance of science in day-to-day life.
Demonstrate an activity of mixing mustard oil with water and the learner should be
asked to suggest the method of separating mustard oil from water. Try to introduce the
use of separating funnel to separate the two liquids that do not mix with each other. It
would be interesting for the students to note that mustard oil will form a layer on top of
water. Can water settle above layer of mustard oil? What will this depend upon? The
students can be given an opportunity of a brain storming session to give the logical
answers.
15
In vocabulary development, introduce the term miscible liquids and immiscible
liquids. Miscible liquids are those that mix with each other (intermix) such as lemon
juice and water and Immiscible liquids are those that do not mix with each other such
as mustard oil and water. Can miscible liquids be separated by separating funnel? Such
answers must be obtained from the students.
Health related Value education can be further strengthened by taking the example of
Air - as a mixture. Smoke from vehicles etc. causes pollution in the air and becomes bad
for health. Ask students about their awareness regarding issue of pollution certificate.
Its importance could be highlighted as a welfare regulation act for industry or vehicles.
Refrain from giving all information to the students and allow the students to put on
their thinking caps and develop the concept of mixtures and the use of appropriate
methods of separation.
Consolidate the unit by making the students apply their knowledge to tell the need to
separate the mixtures. Following points could be extracted from the students:
1. Separate undesirable substances from mixtures (e.g. pebbles from pulses).
2. Separate un-useful substance such as tea leaves from tea. Tea leaves can be used
for other purposes. Help the students’ brain storm to find the answers.
3. Separate desired substances such as precious stones from rocks.
Show some pictures or video clipping to show the process of separating cream from
milk/curd by churning. It will be interesting to relate it back to the Grandma’s time or
a village life or even present day kitchens when many people still use this method. The
term centrifugation could be used at this stage. The teacher should be able to make the
students use their knowledge skillfully to name the types of mixtures that can be
separated by centrifugation.
For an extended learning the teacher should make the students relate the formation of
two layers in case of liquid-liquid mixture on the basis of their lighter and heavier
liquids to the layers of cream which is lighter hence will float on the milk/curd.
16
Mention a type of mixture that will need more than one method of separation. E.g. a
mixture of dries leaves, sand and water will require a combination of methods to
separate the components from the mixture. The process of filtration will be used to
remove dried leaves followed by sedimentation for the sand to settle down and then
decantation for water to separate from sand.
Students can be given group activity to list few mixtures like these and to write the
combination of methods to separate the components.
To enhance logical reasoning the students should be encouraged answer questions
such as:
Why one method is unsuitable for certain mixtures?
Is the sequence of using methods of separation in a combination relevant or not?
Keep in mind that her approach is from known to unknown and from simple to
complex. The teacher must ensure that the students are facilitated to apply their
knowledge from day-to-day experiences and hence experiential learning takes its own
course. While topic is developed the students’ observation skill, thinking skill,
experimental skill is enhanced.
17
TEACHER STUDENT SUPPORT
MATERIAL (TSSM)
18
SEPARATION OF MIXTURES
1. INTRODUCTION:
This unit deals with the study of the mixtures. Also why we need to separate the
constituents of mixtures and the various methods available to do that.
The separation of mixtures into its constituents/components is an important process
use frequently in our daily life. The constituents of any mixture can be separated on
the basis of differences in their physical and chemical properties e.g., particle size
(small, big, solubility, effect of heat (temperature) etc. there are different kind of
mixtures that we deal with at different times.
19
2. Mixtures:
A mixture is a blend of two or more substances in such a way that the particles can
be separated by physical means.
The substances that make up a mixture are called its constituents/ components.
Most of the things we come across in our daily lives such as milk, sea water, soft
drinks, smoke are mixtures.
(i) TYPE OF MIXTURES:
Mixtures are of two types, homogeneous and heterogeneous.(for information
not to be tested)
• Homogeneous mixtures have the same composition throughout the sample.
They are also called solutions. Examples of homogeneous mixtures are air,
sea-water, gasoline, brass etc.
• Heterogeneous mixtures consist of two or more parts (phases), which have
different compositions. The constituents and can be seen with the naked eye
e.g., sand and salt, chalk powder in water etc.
Table 1
Some common examples of mixtures & their constituents are given below
S.No MIXTURES CONSTITUENTS
1. Milk Water, cream, proteins, carbohydrates, fats, vitamins
&minerals
2 Tap water Water, dissolved salts
3 Smoke Carbon particles and air
4 Air Oxygen, nitrogen, carbon dioxide, water vapour
5 Sea water Water , large number of salts of metals
6 Cup of tea Water, tea leaves, milk, sugar
20
http://www.usd116.org/apalla/chem/unit2/notes/images/Pure_Mixture.jpg
Table: 2
DIFFERENT KIND OF MIXTURES WITH EXAMPLES
solid –solid mixtures,
Soil is a mixture of clay &sand
solid- liquid mixture Tiny particles of clay suspended in water
solid- gas mixture,
Soot &ash in air
liquid-liquid mixture Milk is a mixture of tiny droplets of fatty
oil in water
Liquid-gas mixture,
Water vapour in the air condenses above
the cool surface of a lake or field.
When you press the knob of an aerosol
can, a mist of liquid droplets in a gas are
seen
Gas - gas mixture,
Air
21
ACTIVITY 1. (http://www.usi.edu/extserv/kidschem/lesson3.htm)
Have students stand in a circle and make them toss a ball to each other. Each time they
toss the ball they are to name a mixture. The teacher will write these on the board or on
a large sheet of paper.
Remind the students that in brainstorming, no idea or suggestion is "silly." All ideas
should be respectfully heard. Take an uncritical position, encourage wild ideas and
discourage criticism of ideas. Have them raise their hands to respond. Write their ideas
on the board.
Aim: To familiarize with the different kind of mixture using examples from our daily
life.
For eg.
S. No Student response Teacher comment
1 Ice cream Yes
2 Soft drinks Yes
3 Distilled water No
4 Soup Yes
5 Juices Yes
6 Sugar No
7 Sugar solution Yes
22
The pie diagram below shows that air and sea water are mixtures where the
components are in variable proportions.
Sea Water –A mixture of salts Air – A mixture of gases
23
WORKSHEET -1
Study the components of a mixture.
The teacher displays different mixtures and will ask the students to observe and list of
the components of each mixture. (One is done for you)
Mixture Components of each mixture
Mist
Water droplets and air
Aerosol spray
24
(ii) CHARACTERISTICS OF A MIXTURE:
• The components of the mixture exhibit their own physical and chemical
properties. For e.g. in a mixture of salt and sand, the grains of sand and the
crystalline nature of salt are retained. Also salt will show solubility in water
unlike sand.
• The components of a mixture can be easily separated using physical means
like filtration, evaporation etc
• There is no evolution or absorption of energy during the formation of a
mixture.
• A mixture has no definite physical properties like boiling point & melting
point. These change with the change in amount of constituents of the mixture.
3. NEED FOR SEPARATION OF COMPONENTS:
No substance in nature is pure. All substances contain some undesirable substances
in them which have to be removed before human consumption. The removal of
these components is called as separation of mixtures.
25
Table 3
S.NO Reason Examples
1
To remove undesirable components.
Small stones present in rice
&pulses, fine suspended
sand &clay present in pure
water.
2 To remove non useful components. Tea leaves from tea, lemon
seeds from neembu
(lemon) pani, removing the
banana peel.
3 To separate two or more different
components.
Churning of milk to obtain
butter, separating oil from
water, components of air,
green apples from red apples.
4 To obtain desirable components.
Obtaining precious gems
from rocks, obtaining rice
from a mixture of rice &husk
26
FORMATIVE ASSESSMENT -1
FILL UPS: (refer the fig. given before)
Q1) a) Air and sea water are --------------------------.
b) The two main gases in air are _____________and ________________.
c) Sea water is a mixture of water , ________________ of metals.
Q2) Looking at the pictures below answer the following questions:
1) (Fig2.a)A solution of sugar and water is a mixture. Give two reasons to support
your answer.
2) (Fig2.b) How can you separate the components of this mixture?
3) (Fig2.c) Which property is used to separate a mixture of sulphur and iron
fillings.
Fig2.a) A solution of sugar in water
Fig2.b) Fig 2.c)
27
Q3) Give two reasons to support that
a) air is a mixture of gases. b) sugar solution is a mixture.
4. SEPARATION OF COMPONENTS OF A MIXTURE: METHODS
The separation of the various constituents of different mixtures depends on the
properties of the constituents. Some of these properties are size, density, magnetic
nature of particles, solubility, miscibility, differences in boiling and melting points.
A. Separation the Components of a (solid-solid) Mixture
(i) Winnowing
It is that process by which we can separate any heavy material from a lighter one
with the use of wind. It is a relevant method of separation in case of solid-solid
mixtures having components of different weights. For e.g. the wheat grains from
the field still have dried husk and chaff, which have to be separated and thrown
away before the wheat can be used. The husk is blown away as it is much lighter
than the grain. So, when the grains are gently dropped to the ground, only the
wheat grains collect there, while the husk blows away.
Mona,
There are ways to separate Mixtures…
Lets do them One by One…
Evaporation
Filtration
Hand Picking
Sieving
Decantation
Winnowing
28
Winnowing fan
(ii) Sieving is a method of separating substances that are of different sizes .The
component, having a smaller size than the holes of the sieve, passes through while
the other components remain on the sieve. For example, wheat flour has some fine
powdered wheat as well as some bigger impurities. When it is put on a sieve, the
fine powder falls through the small holes in the sieve, while the large size particles
remain as they are too big to pass through these holes. The substances are thus
separated.
sieve
(iii) Hand picking
Handpicking is the basic method for separating components of different texture,
appearance and sizes.
29
It involves simply picking out substances by hand and separating them from
others. The substances being separated may be impurities that have to be thrown
away.
It could also be that both the substances being separated are useful – such as
separating green grapes from black ones
Demonstration of the methods of hand picking, winnowing and sieving through
simple activities.
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Activity - 2a
Aim: To separate a mixture of colorful beads of different sizes/ coins of different
denominations).
Learning Outcomes: Student will be able to analyze the different processes of
separating solid-solid mixtures.
Student will be able to understand when & where the process of handpicking
winnowing and sieving will be used.
Material required: coins of different denominations
Method: The students will be provided with different samples and asked to separate
them.
Record your observation: ---------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
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Activity - 2b
Aim : To separate a mixture of small stones and bits of paper.
Material Required: Small stones and bits of paper.
Method: The students will be provided with mixture, and asked to separate them.
They can use a fan if there is no breeze.
Bits of paper small stones
Record your observation: -------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
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Activity - 2c
Aim : To separate a mixture of wheat flour and rice grains.
Material required: Mixture of wheat flour and rice grains, sieve.
Method: Write the steps you would follow to do the above activity
--------------------------------------------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
Record your observation: ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------
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Activity - 2d
Aim: To separate a magnetic component from a mixture containing non-magnetic
components.( for eg iron and sulphur).
Principle: The magnetic component of the mixture is separated with the help of the
magnetic attraction.
Materials required: mixture of sulphur and iron, magnet
Method: A magnet is moved over the mixture containing the iron filings.
Record your observation: -------------------------------------------------------------------------------
-------------------------------------------------------------------------------------------------------------------
35
WORKSHEET - 2
To separate components based on their properties.
Teacher displays different mixtures (solid mixtures) .
Study the mixtures given and suggest the type of separation method. Also support
your method by filling the property you would use to separate each component.
Students get handouts to fill after their observation.
MIXTURES PROPERTY USED TO
SEPARATE
METHOD OF
SEPARATION
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B. Separating the Components of a Mixture (solid- liquid)
(i) Sedimentation and Decantation
Sedimentation is the process by which insoluble heavy particles in a liquid
are allowed to settle down. This is a simple process that most people use at
home. For example, settling of mud particles in water, tea leaves in hot water.
Decantation is the process by which, a clear liquid obtained after
sedimentation, is transferred into another container, without disturbing the
settled particles.
Separation of the coarse particles of a solid from a liquid by sedimentation and
decantation
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Activity-3a
Aim : To separate the mixture of particles of a solid from a liquid e.g., muddy river
water .
Learning outcome: To observe different methods of separating solid-liquid mixture.
Teacher demonstrates the process of sedimentation and decantation.
Materials required: mixture of sand and water, a beaker.
Principle: The particles of the solid being heavier than the liquid (usually water), settle
down. The clear upper layer of the liquid is then gently poured out into another
container. Settling down of the solid particles due to the effect of gravity is called
sedimentation. The transfer of the clear upper liquid without disturbing the settled
solid particles is called decantation.
Decantation: allowing the top liquid to flow (figure 1)
Method: we take a mixture of sand and water in a beaker and let it stand for sometime.
Record your observation: -------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------
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(ii) Filtration:
Mixtures can often be separated by filtration. The mixture is poured over a piece
of paper that only allows molecules below a certain size to pass through it. The
larger components of the mixture will be trapped on the paper. For example a
mixture of sand and water can be separated as shown in the fig below.
Fig 2: Demonstrating various stages of filtration
Observe the stages a) to c) carefully. What fo you think would have happened ?
What could have happened had we used an ordinary paper in the funnel ? where else
did you not the use of a filter paper in everyday life ? the solid remains on the filter
paper and is called a residue. While the liquid that gets collected in the beaker below
is called filterate.
Can we say a filteration process helps to separate a filtrate from the residue ?
Residue: The solid that remains on the filter paper
Filtrate: The liquid that is collected
Filtration is not limited to solid-liquid separations such as sand and water. There is also
a filtration system present in air-conditioners, where dust and dirt particles are
cleansed from the air by the air filter.
39
Activity-3b
Aim : To separate the insoluble solid component of a mixture from the liquid
completely.
Learning outcome: Student will be able to understand the process of filtration.
Materials required: mixture of sand and water, beaker, filter paper, funnel.
Principle: The solvent molecules present in the solution can pass through the porous
membranes while the suspended particles cannot and are retained on the porous filter
paper.
Method: we take a mixture of sand and water in a beaker and clamp the funnel to a
stand and insert a filter paper in the funnel .
Place a clean beaker below the funnel, and pour the mixture in small quantities into the
funnel using a glass rod.
Record your observation: -------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------
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(iii) Evaporation
Separating homogeneous mixtures can be more difficult. The common way to separate
these mixtures is by Evaporation
This method is useful for separating a soluble solid from a liquid (a soluble substance
dissolves in water to form a solution).
For example: separating salt from sea water, copper sulphate crystals can be separated
from copper sulphate solution using evaporation.
NOTE: It is the water that evaporates , not the solution.
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Activity - 3c
Aim : To separate a soluble solid (salt) from a liquid.
Learning outcome: Student will be able to understand the process of evaporation
Material required: mixture of salt and water, porcelain dish, beaker, Bunsen burner.
Principle: Liquids evaporate at all temperatures. Evaporation becomes faster at higher
temperatures
Method: we take a mixture of salt and water in a beaker and heat it on a Bunsen burner.
Record your observation: ---------------------------------------------------------------------------------
--------------------------------------------------------------------------------------------------------------------
(iv) CENTRIFUGATION
The process of separating lighter component from a heavier component in a
mixture by churning is called (centrifugation) .demonstration of the process of
centrifugation can be followed by discussion.
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Activity - 3d
Aim : To separate a mixture of cream and milk.
Learning outcome: Student will be able to understand the process of centrifugation
(churning)
Material required: full cream milk, churner, blender ? mixie ?
Method: Take a mixture of full cream milk and put it in a churner. Switch on the
machine and allow it to work for few minutes. What do you observe.
Record your observation: ---------------------------------------------------------------------------------
---------------------------------------------------------------------------------------------------------------------
Practice Question: Devesh has a mixture of salt, sand and stones. He needs to separate
these components from the mixture.
Write the order 0f steps he could take to separate the mixture. Also mention the
components separated in each step.
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WORKSHEET- 3
Separation of solid-liquid mixtures.
1. Identify the method of separation in each of the pictures given below.
i)
---------------------------------------------
ii)
---------------------------------------------
iii)
---------------------------------------------
iv)
---------------------------------------------
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FORMATIVE ASSESSMENT: 2
FILL UPS:
1. Pebbles can be separated from grains by-----------------.
2. Cream can be separated from milk by----------------------.
3. The removal of husk from grain is called------------------.
4. The process of settling down of insoluble particles in a suspension is called ---------.
5. Common salt is obtained from sea water by------------------.
6. Before cooking, rice or pulses are washed with water. This water is removed by a
process called------------------.
7. Label the fig shown above.
8. A sieve can be used to separate pulses from water:
a) How does the sieve trap the pulses?
b) what would happen if the sieves holes were bigger than the pulses ?
9. Explain with the help of a flow chart, how would you separate a mixture of salt
and pepper.
10. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
C. Separating the Components of a Mixture (liquid- liquid)
Liquid-liquid mixtures can be separated using a separating funnel. It is used to
separate liquids of different densities as these liquids do not intermix. They form
separate layers.
45
Activity - 4
Aim : To separate a mixture of oil and water using separating funnel.
Learning outcome: Student will be able to understand how to separate liquid mixtures
of different densities by taking a mixture of oil and water
Teacher demonstrates separation of oil from water using the process of decantation.
Materials required: mixture of oil and water, separating funnel, beaker, tripod stand.
Method: Take a mixture of oil and water. Set up the apparatus as shown in fig. below.
. –
Place a empty beaker under the funnel and allow it to stand for some time. The oil
forms a separate layer above water. Would it help to use a filter paper to separate the
above mixture ?
Record your observation: -------------------------------------------------------------------------------
-----------------------------------------------------------------------------------------------------------------
Video clipping: http://www.youtube.com/watch?v=vcwfhDhLiQU
46
WORKSHEET – 4
Separation of Liquid Mixtures. (Oil and Water)
1. i) Identify the apparatus.
ii) What is it used for?
iii) Which liquid forms the top layer and why?
2. Mustard oil gets accidentally mixed with water. How would you remove mustard
oil from water?
3. Following are the pictures of two funnels. what are they used for?
(a) (b)
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SUMMATIVE ASSESSMENT
Q. 1. State whether the following statements are true or false?
a) A mixture of milk and water can be separated by filtration.
b) A mixture of powdered salt and sugar can be separated by process of
winnowing.
c) Separation of sugar from tea can be done with filtration.
d) Grain and husk can be separated with the process of decantation.
Q. 2. Fill up the blanks:
a) The method of separating seeds of paddy from its stalks is called ...................
b) When milk, cooled after boiling, is poured onto a piece of cloth the cream is
left behind on it. This process of separating cream from milk is an example of
....................
c) Salt is obtained from sea water by the process of ...................
d) Impurities get settled at the bottom of a bucket when muddy water is kept
overnight in it . The clear water is then poured off from the top. The process
of separation used in this example is called ....................
Q. 3. Choose the correct option in each of the following:
i) The diagram shows the stages involved in preparing filter paper for a filtration.
Which one of the following is the correct order for the folding of the filter paper?
48
a) C D A B
b) B D A C
c) C A D B
d) A B C D
ii) The diagram shows on apparatus for separating soil
and water. What are the labeled parts called ?
a) A = filtrate, B = residue
b) A = residue, B = distillate
c) A = distillate, B = filtrate
d) A = residue, B = filtrate
iii) The separation technique that involves heating a solution until the liquid
changes into a gaseous state is known as
a) vaporization
b) filtration
c) decanting
d) evaporation
iv) Name the separation technique shown in the
diagram
a) evaporation
b) sedimentation
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c) decanting
d) filtration
5. All life in the world majorly depends on the presence of air. Is it an element, a
compound or a mixture?
A. Element
B. Compound
C. Mixture
6. An unknown, clear liquid is given to you in a beaker. You transfer the liquid from
the beaker to a clean, empty test-tube, and begin to heat it. After a while, you see
vapours (which on further analysis you discover these are vapors of water) rising
from the test-tube, and pretty soon, all that's left is are a few crystals of salt stuck to
the edges. Was that liquid an element, compound or a mixture? Why would you
say so ?
a) Element
b) Compound
c) Mixture
Q4. Match columns A and B
A B
a) smoke i) A gaseous mixture
b) A sugar solution ii) A gas-liquid mixture
c) Air iii) A solid-gas mixture
d) A lemon-water mixture iv) A solid-liquid mixture
e) Carbonated drink v) A liquid-liquid mixture
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Q5. Complete the table with appropriate terms:
Type of mixture Example Method of Separation
A solid-liquid mixture Filtration
Sand and water
A liquid-liquid mixture
Tea leaves and tea
Q6. Which of the following are mixtures.
a). Chicken noodle soup
b). Salad.
c). Table salt
d). Orange juice.
Q7. How does the process of filtration work? Is it better than decantation give reasons
to support your answer?
Q8. Why does sky become clear after rains?
Q9. How will you separate the following mixtures? Explain your answer giving
specific reason for the choice of your answer
a) Rice and dal,
b) Mud and gravels,
c) Hay and soil,
d) iron nails, salt and sand
clue: step 1: magnetic separation
step 2 : add water . Filtration
Step 3 : evaporate the filtrate
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KEY NOTES
Mixture contains two (or more) substances that are not
chemically joined together
e.g. Air, sea water,
chicken soup
Residue The solid left behind after an experiment (e.g. the
solid left in the filter paper). Sand
Soluble: Can dissolve
Sugar in water
Insoluble:
Cannot dissolve
Sand in water
Solvent The liquid that is used to make a solution
Water, alcohol
Solute A substance that has been dissolved in a solution. Sugar, Salt
Density Is defined as mass per unit volume. /or how heavy
or light a substance is.
52
Summary of Some Methods used to Separate Mixtures
PROCESS What it is used for Examples
Filtration Used for separating a solid from a liquid E.g. separating sand
from water.
Evaporation Used to obtain the solute from a solution e.g. for obtaining salt
from salty water
Sieving Used to separate smaller particles from bigger
ones by passing through a sieve
e.g. flour
Hand picking Used to separate solids of different colours,
shapes &size
e.g. beads, coins of
different sizes
Winnowing Used to separate lighter particles from heavier
ones.
Wheat from chaff
Sedimentation Used to separate heavier solid particles from
a liquid by the process of settling down.
Sand & water
Decantation Used to separate a liquid by gently pouring it
without disturbing the sediment
Sand & water
53
Rubric: Assessment for Learning
PARAMETERS Beginning (1) Approaching (2) Meeting (3) Exceeding (4)
Student is able
to plan
investigations
and set
procedure;
Procedures are
unclear or
absent
clearly
identified
clearly
Identified and
implied.
clearly
identified
and
formulated in
a manner that
can be
replicated
able to execute
investigation
and collect data
un able to
execute
investigation
and collect
data
able to execute
investigation
and collect data
has some clarity
able to execute
an investigation
and collect data
precisely.
Able to
execute an
investigation
and collect
data clearly.
able to evaluate
data and
communicate
findings in a
logical way
Scientific
information is
unclear
Scientific
information has
some clarity.
Scientific
information is
communicated
clearly
Scientific
information is
communicated
clearly and
precisely.
Student has
deep
Understanding
of the topic, can
make
connections
with concept.
Scientific
information has
major
inaccuracies or
is over
simplified
Scientific
information has
occasional
Inaccuracies or
is simplified.
Scientific
information
and ideas are
accurate.
Scientific
information
and ideas
are accurate,
thoughtfully
explained.
all images are from www.google.co.in/images
Shiksha Kendra, 2, Community Centre, Preet Vihar, Delhi-110 092 India
CENTRAL BOARD OF SECONDARY EDUCATION