When we mix 2 or more than 2 substances in any ratio to form a new mass is name as a mixture.
The process of separation of two or more than two mixtures is methods of separating mixtures.
The process of heating of one or more than one components from the mixture and we condense the gas in another place by cooling is name as distillation.
By using this method we distil pure water from ocean water and different components of petroleum we separate from crude oil that we take out from the earth.
This method is a simple distillation process.
If we have to separate two or more liquids from a solution, We use a special type of distillation. It is fractional distillation.
We separate different components of crude oil using fractional distillation method. The process is based on the fact that different components of crude oil have different boiling points.
For it, we have to heat the crude oil at 400° C after this we have to pass it through a long fractionating column from near its bottom.
Between the bottom to the top, the temperature varies from 400°C to 40°C.
We have to divide the long fractionating column into several compartments by means of shelves with holes in them.
We have to cover the holes with bubble caps. These caps allow the light to pass and volatile components up but less volatile components condense and flow into the rays below.
We have to connect each shelf with an overflowing pile, which helps to collect the various fractions separately.
The Russian botanist, Mikhail Tswett invented chromatography at the beginning of the 19th century by which colours are separated.
Chromatography means colour writing. This process helps originally to separate coloured substances present in a mixture.
Nowadays, chromatography is applied to separate and identify colourless as well as coloured substances.
Chromatography is a technique we for separating the components of a mixture by passing it through a column or sheet of an adsorbing material.
The principle of this process depends upon the different component of a mixture is absorb into different extents and move down the column at different rates.
To understand the fact lets put a drop of ink on a filter paper or on a piece of chalk. We will notice that the ink on the chalk or on the filter paper is dark at the centre and light at the edge. Can you say, why?
This is due to different rates of movement of the ink by the moving water which causes separation.
There are severe techniques of chromatography,
1. Paper chromatography
It is a method in which we take a filter paper as an adsorbent material for analyzing mixtures by chromatography.
The water rises up in the roll of the filter paper, spreads across the filter paper and carries the colours with it. Some colours stick more firmly to the fibres of the filter paper than the others. The colouring matter that sticks most firmly remains nearest to the hole and the colouring matter that sticks least goes farthest.
The different rates of movement of the colouring matter by the moving water cause separation. This process is chromatography.
2. Adsorption chromatography
It is based on the principle that a certain adsorbent can adsorb different substances to different extents. When a solution containing two or more than two dissolved substances is to be separated, it is allowed to pour into a vertical glass tube packed with finely divided adsorbent like alumina. The colours of dissolved substances of a solution are separated in the form of brands. Chalk, silicate gel or magneso oxide also can be taken as adsorbing materials in a vertical glass tube instead of alumina.
3. Gas and liquid partition chromatography
Application/uses of chromatography
1. We use it to separate coloured substances present in natural colours.
2. We use it to detect and identify drugs present in the blood.
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