Understand Mixtures and ways to Separate Them

What is a Mixture?

A mixture is a combination of two or more two substances in any proportion. The one special feature of the mixture in chemistry is that when we combine these two different substances, they do not change their identities. 

If the components lose their identities, then the result will not be a mixture. The most common example of a mixture is air. It is a mixture of many gases but, all the gases keep their distinctive properties.

Types of Mixtures:

• Heterogeneous mixture: This type of mixture has different properties and compositions. For example, the mixture of sand and salt or oil and water.
• Homogeneous mixture: This type of mixture has similar kinds of properties and compositions. For example, water and sugar or salt and water.

Based on these categories, the mixture is divided further into these specific types:

• Solution: A solution is a homogeneous mixture where one substance dissolves in the other substance. The substance which gets dissolved is called the solute, and the other substance is called the solvent. For example, sugar is solute, and water is solvent.
• Colloid: Colloid is a heterogeneous mixture wherein the two substances don’t dissolve in each other. Instead, the particles are suspended and are not settled to the bottom. For example, blood is a colloid.
• Alloys: Alloys is a homogeneous mixture where one of the substances has the properties of the metal. For example, steel is a mixture of iron and carbon.
• Suspension: Suspension is a heterogeneous mixture where one substance doesn’t get dissolved. Instead, if left for some time, it can be seen at the bottom of the mixture. For example, sand and water. 

Separating Mixtures

We have understood the meaning and different types of mixtures; now, we will look at the methods of separation of mixtures with various techniques.

• Hand sorting
• Sieving
• Threshing
• Winnowing 
• Filtration
• Magnetic separation
• Evaporation
• Condensation
• Distillation
• Separating funnel

Hand sorting: This is the simplest method of separating mixtures. For example, the mixture of safety pins and paper clips. Here both the substances are useful. But sometimes, the other substance can be impure; for example, the small stones are handpicked from wheat grains.

Sieving: Once the wheat grains are separated from fine stones, it goes through the sieve to separate the wheat grains from the sand. The pores of the sieve easily remove the sand, and this type of process is called sieving.

Threshing: Once the wheat crop is cut, it is threshed to get the wheat grains from the harvest. The stalks of wheat grains are beaten, and thus the separation process is completed.

Winnowing: Generally, in this type of separation process, the help of wind is taken. Once the wheat grains are collected, they are full of husks and chaffs, which need to be separated. When the mixture is thrown from some height, the husks and chaffs get separated with the help of wind. Since the grains are heavier, they get separated and collected in one place.

Filtration: When solids and liquids are mixed, then the filtration process is used. For example, if sand and water are mixed, a filter will be used to get sand out of water. Sometimes filtering paper is used depending upon the mixtures.

Magnetic separation: Magnetic separation can be used where one of the substances have magnetic properties. The ore minerals in the mixture will stick to the magnet, and the non-magnetic substance will get separated. 

Evaporation: This method is used when one of the substances gets dissolved in the water. When the mixture is heated, the solvent gets evaporated, and the solid residue is left behind. Thus, the process of separating mixtures is completed. 

The common salt which is used in every home is an example of this process. The seawater contains salt. Once it is left in the shallow pits with the help of sunlight, the water evaporates, and salt is left behind.

Condensation: In the process of Evaporation, the water which is being evaporated can also be collected with the help of condensation. For example, if the saltwater is kept in the kettle and heated, water vapours will come out of the spout. 

If a metal plate is held in front of the spout, then vapours will be collected and once cooled, the water can again be collected in a bottle. With the help of this process, both water and salt can be collected.

Distillation: Distillation is the next step of condensation. The apparatus used in this process is called still. The seawater is placed in the flask. Once the seawater is boiled, water vapours are produced. The water is condensed in the tube and is collected again. The salt cannot be evaporated, so that it will be left in the flask.

Separating funnel: This process separates the liquids that can not get dissolved in each other. For example, water and oil. To separate this kind of liquid, a separating funnel is used. 

The separation process is different for different mixtures. It is important to remember that different substances have different properties, and while separating them, we need to consider them. Most of these mixtures are available there and used in our daily lives. 

When fine stones are taken out of rice at home or the water purification machines are working in front of us, we can see many examples of separating mixtures in our day to day lives. 

So, chemistry is not at work only in a lab, but it is used by everyone somehow. The idea is to use the methods mentioned above and get the materials separated. 

Some key points to remember: 

• The substances in a mixture do not change their properties. 
• The most common mixture is air which we use all the time to breathe.
• Mixtures can be liquid, gas or solid.
• While separating the mixtures, remember the properties of each substance so that the right technique can be used to separate them.