SEPARATION OF SUBSTANCES

In our daily life, there are many instances when we notice a substance being separated from a mixture of materials.

Example- 

• Tea leaves are separated from the liquids with a strainer while preparing tea.
• Churning milk to obtain butter

Methods of separations-

The substances to be separated may be particles of different sizes or materials. These may be in any three states of matter ie solid, liquid, or gas. So there are various methods of separation which are as follow-

(1)Handpicking-

• Handpicking used for separating slightly larger sized impurities like the pieces of dirt, stone, and husk from rice and pulses.

(2)Threshing-

• The process that is used to separate the grain from stalk. In this method, the stalks are beaten to free the grain seeds.

(3)Winnowing-

• It is used to separate lighter and heavier components of a mixture by wind or by blowing air. This is commonly used by farmers by separating lighter husk particles with the help of wind, from heavier seeds of grain.

(4)Sieving-

• Sieving allows the fine particles to pass through the holes of the sieve while the bigger impurities remain on the sieve.

(5)Sedimentation-

• Sedimentation When the heavier component in a mixture settles after water is added to it.
• Example – soil and Water

(6)Filtration-

• It is a process used to separate solids from liquids or gases using a filter medium that allows fluid to pass through but not solid.

(7)Evaporation –

• The process of water into vapour obtained from process conversion salt is. of evaporation.

(8)Condensation-

• The process of conversion of water vapour into its liquid form.

EXERCISE

1. Why do we need to separate different components of a mixture? Give two examples.
Answer:

Separation is a process in which we remove unnecessary materials from the mixture. This is done to remove impurity from the mixture and make use of wanted component.

For example:
(a)we separate sand from water by the process of filtration.
(b)Stone is separated from Pulses.

2-What is winnowing? Where is it used?
Answer:

Winnowing is a method of separating components of a mixture. It is used to separate the lighter components of a mixture by wind or by blowing air. This method is used by farmers two separate lighter husk particles from heavier seeds of grain.

3- How will you separate husk or dirt particles from a given sample of pulses before
cooking?

Answer:

Husk or dirt particles are separated by winnowing.

4-What is Sieving? Where can it be used?

Answer:

Sieving allows the fine particles to pass through holes of sieve while bigger impurities. remain on the sieve. This is used to remove husk-like impurities and stones from wheat in a flour mill.

5-How will you separate sand and water from their mixture?
Answer:

When a heavier component in a mixture settles after water is added to it, the process is called sedimentations so by this process sand settles down at the bottom of the mixture. After that, we will pour water into another jar and the mixture will be separated. We call this process decantation.

6. Is it possible to separate sugar mixed with wheat flour? If yes, how will you do it?
Answer:

Yes, Sugar can be separated from wheat flour by sieving. As sugar is bigger impurity and flour are fine so the sugar will stay on a sieve and wheat flour will pass through it.

7-How would you obtain clear water from a sample of muddy water?
Answer:

We will obtain clear water from a sample of muddy water by the process of filtration. A filter paper is folded in a glass and then the mixture is poured on the paper. Water passes through it and impurity remains in paper.

8. Fill in 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 (malai) 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 settled at the bottom when muddy water was kept overnight in a bucket.
The clear water was then poured off from the top. The process of separation used in this
example is called ______________.

(a) threshing.

(b) filtration.

(c) evaporation.

(d) Sedimentation and decantation

9-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 the 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. 

(a) Flase

(b) False

(c) False

(d) False

10. Lemonade is prepared by mixing lemon juice and sugar in water. You wish to.
add ice to cool it. Should you add ice to the lemonade before or after dissolving
sugar ? In which case would it be possible to dissolve more sugar ?
Answer:

We should add ice after dissolving sugar as temperature is high.After mixing ice in it less sugar will dissolve in it.