VI- CHEMISTRY CHAPTER -3

SEPARATION TECHNIQUE

SYLLBUS Separation of components of mixtures, Method of separation

of Solid in Solid Mixtures, Methods of separation of solid in

liquid mixture, Method of separating of gas in liquid mixture.

TOPICS COVERED

Introduction

Separation Of Components Of Mixtures

Method of separation of solid in solid mixtures Winnowing

Sieving

Handpicking

Magnetic sepration

Sublimation

Methods of separation of solid in liquid mixture

Sedimentation and decatation

Filtration

Centrifugation

Evaporation

Methods of separation of liquid in liquid mixture

Methods of separation of gas in liquid mixture

Obtaining pure substance using a combination of

different methods.

Reason for preferring a particular technique over

another.

Substance can be separated from a mixture of materials.

Tea leaves are separated from the liquid with a strainer while

preparing tea.

Grain is separated from stalks, while harvesting, Milk or curd

is churned to separate butter.

Separation of components of mixtures

The process by which unwanted or harmful components of a

mixture is removed to get desirable or pure component is

called Separation of components from a mixture.

The Separation of a mixture depends upon the type of

mixture, its nature and the characteristics properties of the

component present in that mixture.

Method of separation of Solid in Solid

Mixtures

There are various methods of separating the

components of solid in solid mixtures.

1. WINNOWING

It is defined as a process to separate light solid substance

from heavier ones by using wind.

The mixture of wheat and husk is taken in a convenient

vessel is allowed to fall down from a height. The wind carries

the lighter husk with it. The wheat grains being heavier fall

vertically down to the ground and form a heap. The husk

particles form a heap, at a short distance away from the heap

of wheat grains.

2. SIEVING

It is defined as a process to separate undesirable components

in a Solid-Solid Mixtures by using a sieve.

A sieve has very small holes which allow very fine particles to

pass through them.

The coarse particles are retained in the sieve and are thus

separated.

3. HANDPICKING

It is defined as a process to separate undesirable constituents

from a mixture by picking with hands. It is normally done to

separate undesirable heavier particles such as small pebbles

from wheat, rice, pulses.

4. MAGNETIC SEPARATIONS

This is a method of separating magnetic substance from non-

magnetic substance in a mixture with the help of a magnet.

When the magnet is moved over the mixture, the magnetic

substance clings to the magnet, leaving the other non-

magnetic substance behind.

In many factories, scrap iron is separated from a heap of

waste materials by using big electromagnets fitted to a crane.

5. SUBLIMATION

On heating most of the solid first change into liquid and then

into their gaseous states. However, on heating some solid

change directly to their gaseous state without changing into

liquid. This is known as sublimation. Some examples of such

solids are ammonium chloride, camphor, naphthalene and

Iodine.

Click the link below to have better understanding to the topic

Method of separation of Solid in Solid Mixtures

https://youtu.be/0Rt_AoHJSEs

Methods of separation of solid in liquid mixture

There are various methods of separating the components of

solid in liquid mixture such mixtures can be homogenous and

heterogeneous.

1. SEDIMENTATION AND DECANTATION

This method is used for separating insoluble solid from a

liquid

The process of allowing the suspension of insoluble solid to

settle down at the bottom of the container is called

sedimentation the process of transferring the clear liquid

without disturbing the sediment is called decantation

Purification of water for drinking purpose is done by allowing

natural water to stand in a big thanks where most of the

suspended particles of mud settle down the clear water is

decanted out from the outlets located at a convenient points

in the tank this is further purified if necessary in this process

course and heavy solid particles settle down very easily and

quickly while very fine or light solid particles such as fine mud

or clay do not settle down easily.

Sometimes to increase the rate of sedimentation of particles

in muddy water, pieces of alum are added to the mixture this

process is called loading thus the process by which insoluble

small suspended particles in a solution and heavier in order

to increase the rate of sedimentation of particles is also

called loading.

2. FILTRATION

It is the process of removing an insoluble substance from a

liquid by allowing it to pass through a filter paper or muslin

cloth alteration is often used in our homes, laboratory and

industries

Click the link below to have better understanding to the

topic Sedimentation and Filtration

https://youtu.be/sBCLafMPVt8

3. CENTRIFUGATION

It is a method used for separation of fine suspended particles

of a substance in a liquid. In this method the liquid containing

the fine suspended particles is rotated at a very high speed in

a close container the heavier particles move towards the

bottom of the container and light particles remain about the

heavy ones on the top. Centrifugation is generally used in

Laboratories; it is also used in daily use to separate cream

from milk. Milk is rotated at a very high speed in a closed

container cream being lighter than milk floats on the top and

gets separated.

4. EVAPORATION

The process in which liquid changes into vapour without

being boiled is called evaporation. This method is used to

recover a solid dissolved in a liquid; the process is used on a

large scale to obtain common salt from seawater

Seawater which contains dissolved salt is allowed to flow

into Shallow ponds the heat of the sun evaporates the water

and solid salt is left behind in the pond

Click the link below to have better understanding to the

topic Evaporation https://youtu.be/hp8H54gMK6Q

Methods of separation of liquid in liquid

mixture

If a liquid get mixed with another liquid the two liquids are

called miscible liquids example crude oil and petroleum.

If a liquid does not mix with another liquid then the two

liquids are called immiscible liquids for example water and oil

two immiscible liquids can be separated by using a separating

funnel the mixture of immiscible liquid is taken into the

separating Funnel in the content is allowed to stand for

sometime the content in the separating funnel forms two

layer an upper and lower layer. On opening the stopcock the

lower layer can be drained completely and close this stopper

the light liquid remains in the separating funnel

Click the link below to have better understanding to the

topic Methods of separation of liquid in liquid mixture

https://youtu.be/7oqLUIHpqOc

Method of separating of gas in liquid mixture

A mixture of gas in liquids can be separated by heating on

heating, the dissolved gas escapes from liquid.

Drinking water contains air dissolved in it when it is boiled,

the air escapes the boiled water becomes tasteless.

Separation of constituent of the mixtures

(i)To separate the constituents from a mixture of sawdust

and common salt

Take the mixture in a glass beaker.

Pour water in a glass beaker till it is half filled.

Stir the mixture properly and allow it to stand for some

time.

Sawdust being lighter floats on the surface of water

while sand heavier settles down in the beaker.

Now slowly pour the salt solution along with sawdust on

the filter paper fixed in the funnel.

The solution passes through the filter paper in the

conical flask while sawdust remains on it.

Dry all sand particles in the sunlight left in the beaker as

a sediment.

Take the salt solution and heat it till all the water

evaporates into the atmosphere.

A white solid of common salt is left behind.

Thus, all the constituents of the mixture are separated.

(ii)To separate the constituent of mixture of iron filings,

sulphur and common salt

Take the given mixture in a vessel and role of bar

magnet in it.

The iron fillings cling and stick to the two poles of the

magnet.

Repeat at least three times till no more iron fillings get

attracted towards the pole of a magnet.

Now, take the Residual mixture of Sulphur and common

salt in a beaker.

Add water in the beaker till it is half filled and stir it

properly.

Filter the mixture.

Sulphur being insoluble is left on the filter paper as a

residue and salt solution is collected as filtrate in the

funnel.

Remove the sulphur from the filter paper and dry it in

the sunlight.

Take the salt solution and heat till all the water

evaporates in the atmosphere.

The white solid left behind is common salt.

Thus, all the constituents of the mixture are separated.

Obtaining a Pure substance using a

combination of different methods Very often pure substance are obtained by using

combination of different methods of separation for

example, common salt obtained from sea water is

purified by the combination of various methods. It is

crushed dissolved in water, filtered, evaporated and

then crystallized to get pure salt.

Reason for preferring a particular technique

over another

The following are the reasons for preferring a particular

technique over another

To remove impurities that are harmful and

undesirable.

To obtain useful component.

To obtain a pure sample of a substance.

WORKSHEET

1. A mixture of wheat and husk can be separated by

(a) Handpicking

(b) Winnowing

(c) Sieving

(d) None of these

2. A mixture of water and kerosene can be separated by

(a) Separating funnel

(b) Evaporation

(c) Decantation

(d) None of these

3. A mixture of iron fillings and leaves can be separated by

(a) Hand picking

(b) Magnetic separation

(c) Evaporation

(d) Sieving

4. Common salt can be separated from common salt solution

by

(a) Filtration

(b) Centrifugation

(c) Evaporation

(d) Handpicking

5. A mixture of Sulphur and water can be separated by

(a) Evaporation

(b) Filtration

(c) Magnetic Separation

(d) Separation winnowing

6. ________ is used to separate the particle of different sizes

from a mixture.

(a) Sieving

(b) Magnetic Separation

(c) Evaporation

(d) Filtration

7. Insoluble sand that settle down at the bottom is called

________

(a) Sediment

(b) Supernatant liquid

(c) Filtrate

(d) Sublimate

8. ________ is used to separate suspended solid particle

from liquid.

(a) Centrifugation

(b) Filtration

(c) Evaporation

(d) Sublimation

9. The process in which liquid changes into vapour without

boiling is called ________.

(a) Evaporation

(b) Sedimentation

(c) Winnowing

(d)Filtration

10. The process used to separate cream from milk.

(a) Centrifugation

(b) Decantation

(c) Sedimentation

(d) Loading

CORRECT THE FOLLOWING STATEMENT.

1. Loading is used to separate cream from milk

2. Crude oil and petroleum are immiscible liquids.

3. The separation of sulphur from iron fillings is separated by

the process of filtration.

Define

1. Sediment

Matter that settles to the bottom of the liquid is called

Sediment.

2. Supernatant Liquid

A liquid floating on the surface above the sediment or

precipitate is called Supernatant Liquid.

Answer the following question.

1. What is sieving?

Ans- Sieving is the process to separate undesirable

components in a solid-solid mixture by using a sieve.

2. Why do we Sprinkle water before sweeping in a dusty

room?

Ans- Water is sprinkled before sweeping a dusty room as it

helps dust to settle down and also prevents dust to fly up

again in the room.

3. How will you separate husk or dirt particles from a given

sample of pulses before cooking?

Ans- The mixture of wheat and husk is taken in a vessel is

allowed to fall down from a height. The wind carries the

lighter husk with it. The wheat grains being heavier fall

vertically down to the ground and form a heap.

4. What is meant by separation of constituents of mixture?

Ans- The process by which unwanted or harmful component

of a mixture is removed to get a desirable or pure component

is called separation of constituents of mixture.

5.Why it is necessary to separate constituents of a mixture?

Ans- It is done for various purposes

To remove harmful component.

To remove unwanted component.

To obtain pure sample.

Answers for MCQ

1. Winnowing

2. Separating funnel

3. Magnetic separation

4. Evaporation

5. Filtration

6. Sieving

7. Sediment

8. Centrifugation

9. Evaporation

10. Centrifugation

Answers for correct the following statement

1. Centrifugation is used to separate cream from milk

2. Crude oil and petroleum are miscible liquids.

3. The separation of sulphur from iron fillings is separated by

the process of magnetic separation.