Mention the techniques used for separation of substance and describe them
Answers
Answer:
1. Winnowing
2. Sieving
3. Sedimentation, Decantation, Filtration
4. Evaporation and Condensation
Explanation:
Winnowing
Winnowing is used to separate lighter components of the mixture from heavier components by the wind. These separation techniques are commonly used by farmers to separate lighter husk particles from the heavier seeds.The lighter particles are carried away by the wind. The heavier seeds form a heap near the platform of winnowing. We can use either natural wind or blow air while winnowing.
Sieving
You might have seen your mother use a sieve to separate impurities and bran from flour before using it. The separation techniques of sieving are mainly used in a flour mill to separate impurities from wheat before grinding it. Sieving removes impurities like stones, stalk, and husk that still remain after threshing and winnowing. The sieve only removes particles of impurities that are larger than the pores in the sieve. Therefore, we can design the sieve according to our need.
Sedimentation, Decantation, and Filtration
The heavier impurities present in water settle down at the bottom of the container after some time. These separation techniques are Sedimentation. The impurities only settle because they are heavy. These separation techniques are not useful for lighter impurities.
Decantation is the slow removal of water to separate the impurities from the water after sedimentation. Filtration is the separation of particles of impurities from water using a filter paper.
Evaporation and Condensation
Evaporation is the process of conversion of water into its vapour state. These separation techniques are useful for obtaining salt from seawater. Let’s perform an activity. When you go to the beach on a sunny day next time, take some seawater in a bowl and keep it aside till you spend some time enjoying. When you come back, you will observe that there is actual salt in the bowl. But where did the salt come from and where did the water go? That is because seawater contains salt and the water evaporates as it heats up.
Condensation is the conversion of water vapour into its liquid state. Have you seen water droplets on the outside of a cold bottle? This is an example of condensation. The temperature inside the bottle is very low as compared to outside. When water vapour comes in contact with the surface of the bottle, it condenses, that is, convert into liquid water and forms droplets on the surface.
We can use more than one method to separate the same two substances. We can use both winnowing and handpicking to separate the husk from grains. But using both will remove all impurities. Therefore, all separation techniques are useful to the farmers.