Question

1. Why do we need to separate mixtures?Give examples to illustrate your answer.​

Answer 1

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• Different components of a mixture are separated in order to either separate the un-required components from a mixture or sometimes, to separate more than one useful components from a mixture.

• For example, grain purchased from shops can contain several impurities such as pieces of stone, husk, broken grains, etc. Thus, grain is separated from these impurities to make it edible.

• Similarly, after preparing tea, we strain it to remove the used tea leaves from tea.

Answer 2

Explanation:

1) To remove unwanted particles

A bhel is a mixture of various ingredients like onion, tomato, potato, chillies, etc. Someone who does not like spicy food will remove the chillies to prevent mouth burn. Therefore, separation is necessary to remove the chillies from food.

Your mother always removes stones from rice before she cooks. Because stones are not wanted. Separation is necessary to remove the stones.

Also, your mother removes the tea leaves from tea using a strainer. We cannot drink tea with the tea leaves. Hence, they are separated.

Air also contains dirt and dust.We have hair in our nostrils which separate the dust and dirt particles from the air.

Did you know that the water we drink comes from rivers and lakes? But it contains impurities and germs. They are not wanted. Thus, Separation is necessary to remove these impurities.

2) To obtain important substances

Some substances are more important than others in a mixture.Therefore, these need to be obtained by separation of substances.

We all love butter. We spread it on a bread and eat it. It is used it for cooking. Butter is prepared from milk.The milk is churned at a high speed which creates a froth up. This froth is actually butter. The oil droplets are collected. Thus butter is separated from milk.

The air around us has many gases. It has oxygen, nitrogen, carbon dioxide, etc. But air also has dust and impurities. The impurities need to be removed so that important gases can be obtained. Oxygen makes up 21% of air. But only oxygen is required for so many things like respiration, burning, etc. There are cylinders present in hospitals which contain only oxygen. They are for the patients who can not breathe on their own. But how does this oxygen come in the cylinder? It has been separated from the air.This is a very important use of separation of substances. Even nitrogen has many uses. Therefore, it is separated from air.

Crude oil is raw oil. It is a mixture of many oils. It has petrol, diesel, kerosene, paraffin wax. But it also contains impurities.We all know petrol and diesel are used in vehicles. Vehicles cannot run without them. Thus, they have to be separated from the crude oil.

3) To obtain pure substances

A mixture is actually made up of pure substances only. But they get mixed with each other in a mixture. Sometimes the individual pure substances are more important than the mixture. For example, Saltwater is not very important to us. But salt and water individually are very useful to us. Hence, we need to separate both from each other.Thus, separation of substances is necessary to obtain pure substances for domestic purposes, industrial purposes and research work.

Even the example used earlier of gases present in air is also an example of obtaining pure substances. We can obtain oxygen in its pure form for many reasons.