6 PPT 2 SEPARATION OF SUBSTANCES

SEPARATION OF SUBSTANCES
PPT-2

TILLSO SO FAR WE HAVE LEARNT......

• MATTER
• ELEMENTS
• COMPOUNDS
• MIXTURES- HETEROGENEOUS AND HOMOGENEOUS

To understand the various methods of separating substances that are mixed
together

 HANDPICKING
 THRESHING
 WINNOWING
 SIEVING

ACTIVITY- 2 (Page no - 36 NCERT)

TIME TO THINK !!!

HOW DOES YOUR MOTHER SEPARATE
TINY STONES PRESENT IN A PACKETOF
PULSES?

WHERE CAN WE USE
HANDPICKING?

THE METHOD OF HANDPICKING CAN BE USED FOR
SEPARATING SLIGHTLY LARGER SIZED IMPURITIES
LIKE THE PIECES OF DIRT, STONE , AND HUSK FROM
WHEAT, RICE OR PULSES.

THIS IS POSSIBLE BECAUSE THE PARTICLES OF THE
UNDESIRABLE SUBSTANCES ARE DIFFERENT FROM
THE FOOD GRAINS IN COLOUR, SHAPE AND SIZE.

THE QUANTITY OF SUCH IMPURITIES IS USUALLY
NOT VERY LARGE.

HOW DOES THE FARMER SEPARATE GRAIN
SEEDS FROM BUNDLES OF STALKS?

THE PROCESS THAT IS USED TO SEPARATE GRAIN

FROM STALKS IS THRESHING.

IN THIS PROCESS, THE STALKS ARE FIRST DRIED IN THE
SUN AND THEN BEATEN TO FREE THE GRAIN SEEDS.

SOMETIMES THRESHING IS DONE WITH THE HELPOF
BULLOCKS.

MACHINES ARE ALSO USEDTO THRESH LARGE
QUANTITIES OF GRAIN.

Video https://www.youtube.com/watch
link: ?v=x4Cp-uQIpOs

TIME TO THINK!!

HOW WOULD YOU SEPARATE A MIXTURE OF DRY SAND
WITH SAWDUST OR POWDERED DRY LEAVES?

•ARE THE SIZES OF PARTICLES OF THE TWO
COMPONENTS SIMILAR?

•WOULD IT BE POSSIBLE TO SEPARATE THE
COMPONENTS BY HANDPICKING?

WINNOWING IS A PROCESS WHICH IS USED

TO SEPARATE HEAVIER AND LIGHTER COMPONENTS
OF A MIXTURE BY WIND OR BY BLOWING AIR.

Video link:
https://www.youtube.co
m/watch?v=_AxxyAKTZ-
g

•THIS METHOD IS COMMONLY USED BY FARMERS

TO SEPARATE LIGHTER HUSK PARTICLES FROM

HEAVIER SEEDS OF GRAIN.
•THE HUSK PARTICLES ARE CARRIED AWAYBYTHE

WIND.
•THE SEEDS OF GRAIN GET SEPARATED AND FORMA

HEAP NEAR THE PLATFORM FOR WINNOWING.
•THE SEPARATED HUSK IS USED FOR MANY

PURPOSES SUCH AS FODDER FOR CATTLES.

SIEVING

SOMETIMES WE WISH TO PREPARE A DISH WITH FLOUR. WE
NEED TO REMOVE IMPURITIES AND BRAN THAT MAY BE
PRESENT IN IT.

WHAT DO WE DO?

WE USE A SIEVE AND POUR THE FLOUR INTO IT.

SIEVING ALLOWS THE FINE FLOUR PARTICLES TO
PASS THROUGH THE HOLES OF THE SIEVE WHILE
THE BIGGER IMPURITIES REMAIN ON THE SIEVE.

WHERE IS SIEVING USED IN DAILYLIFE?

IN A FLOUR MILL, IMPURITIES LIKE HUSK AND STONES
ARE REMOVED FROM WHEAT BEFORE GRINDING IT.

SIEVING REMOVES PIECES OF STONES, STALK AND
HUSK THAT MAY STILL REMAIN WITH WHEATAFTER
THRESHING AND WINNOWING.

IMPURITIES SIEVING IS USED WHEN
SIEVE COMPONENTS OF A
MIXTURE HAVE DIFFERENT
SIZES.

FLOUR

SIEVES ARE ALSO USED AT CONSTRUCTION SITES
TO SEPARATE PEBBLES AND STONES FROM SAND.

ASSIGNMENT BOOKLET QUESTIONS

Q1. CHOOSE THE CORRECT OPTION-

1. The process of winnowing is based on the principle that 2. The method of sieving is used
(I) lighter husk particles are carried away by the wind to separate
(II) heavy grains fall down in a heap (a)components of same size
(III)husk and wheat are completely mixed. (b)components of different sizes
(IV)wheat grains are blown away by the wind (c)soluble impurities
(d)liquid Impurities
Which of the above sentences is/are correct?
Ans. b) components of
(a) I only (b) I and IV (c) I and II (d) II and III different sizes
Ans- (c)- I and II

5. A mixture of rice and stone particles is separated by
a) handpicking
b) sieving
c) winnowing
d) churning

Ans. a) handpicking
4.The process of drying the wheat stalks in the sun and then beating them to

separate the grains is called
a) winnowing
b) threshing
c) churning
d) sieving
Ans. b) threshing

Q. Give Reasons-
a) Winnowing cannot be done in a closed room

Winnowing cannot be done in a closed room because there is
no wind or blowing air to separate the particles.

Q. What is winnowing? Where is it used?
Ans - Winnowing is the method of separation of heavier and lighter
components of a mixture by the wind or blowing air. It is used in
farms to separate husk particles from grains.

Q. What is sieving ? Where is it used?
Ans . Sieving is the method of separation of fine particles by passing
the mixture through the sieve where the bigger particles are left
behind the sieve and the fine particles pass through the sieve.
Sieves are used at construction sites to separate pebbles and
stones from sand.

SUMMARY

THE METHOD OF HANDPICKING CAN BE USED
FOR SEPARATING SLIGHTLY LARGER SIZED
IMPURITIES LIKE THE PIECES OF DIRT, STONE
AND HUSK FROM WHEAT, RICE OR PULSES.
THE PROCESS THAT IS USED TO SEPARATE
GRAINS FROM STALK IS THRESHING.
IN THIS PROCESS, THE STALKS ARE BEATENTO
FREE THE GRAIN SEEDS.

WINNOWING IS A PROCESS WHICH IS USED TO
SEPARATE HEAVIER AND LIGHTER COMPONENTS
OF A MIXTURE BY WIND OR BY BLOWING AIR.

WHEN THE CONSTITUENTS OF A MIXTURE HAVE
PARTICLES OF DIFFERENT SIZES, A SIEVE CAN BE
USED.

SIEVES AREALSO USED AT CONSTRUCTION SITES
TO SEPARATE PEBBLES AND STONES FROM SAND.