Tag: Separation Technique

An Introduction to a Separation Technique: Centrifugation

When we look around, there are many objects of various sizes, shapes, and textures. The element that scientists refer to as matter makes up everything in the cosmos. Everything is matter, including the air we breathe, the food we consume, rocks, clouds, stars, plants, animals, and even a single drop of water or sand. These compounds each have a unique nature and set of characteristics. They might be impure, or they might be completely pure. Looking around, we can also see that everything described above has mass and takes up space.

What are Techniques Available to Separate the Mixture

By using everyday physical techniques like hand-picking, sieving, and filtering, heterogeneous mixtures can be broken down into their components. The components of a combination sometimes need to be separated using specialized methods. Several of these methods include:

• Centrifugation
• Evaporation
• Sublimation
• Chromatography
• Fraction Distillation and Distillation

What is the Principle of Centrifugation

Particles with densities greater than the solvent’s density sink, while lighter particles float to the surface. They move faster when there is a greater density differential. Gravity can be replaced by a centrifuge’s much stronger centrifugal force, which can be used to separate different particles in a solution by exploiting even minor changes in density. The centrifuge operates on the sedimentation principle, which states that denser materials and particles flow outward in the radial direction as a result of centripetal acceleration. As they move to the centre, less dense objects are displaced.

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Process of Centrifugation for separating cream from milk

A separator is a centrifugal machine that separates skim milk from the cream. Milk is a liquid that contains tiny oil droplets suspended in it. The milk is centrifuged in a large, closed machine. When the machine is turned on, the milk is spun at an extremely high speed in a container. As a result, the milk is separated into cream and skim milk. Because the cream is lighter, it floats on top of the skimmed milk. It can then be removed. To separate milk and cream, centrifugation is used.

Summary

Centrifugation, which involves rapidly rotating solutions of molecules around an axis in a centrifuge rotor, can be used to separate different-density molecules. One of the most useful and widely used techniques in molecular biology laboratories.

Frequently Asked Questions

1. What are the applications of centrifugation?
Ans. Some applications of centrifugation are-

• Separation of two miscible substances
• Subcellular organelle fractionation
• Separation of chalk powder and water
• Skimmed milk is made by removing the fat from milk.
• Wine clarification and stabilization

2. What are the methods by which heterogeneous mixtures can be separated?
Ans. Heterogeneous mixtures can be broken down into their constituents using common physical techniques such as handpicking, sieving, and filtering. Sometimes the components of a combination must be separated using specialized methods. Among these techniques are:

• Centrifugation
• Evaporation
• Sublimation
• Chromatography
• Fractional and full distillation

3. What do you mean by Mixture?
Ans. More than one type of pure form of matter, also known as substance, makes up a mixture. No physical process can split a substance into different types of matter.

An Introduction to Chromatography

The Greek words chroma, which means “colour,” and graphein, which means “to write,” are the roots of the word “chromatography.” In this procedure, the mixture to be separated is applied to a stationary phase (solid or liquid), and a pure solvent—such as water or any gas—is then allowed to slowly travel across the stationary phase, transporting the components separately based on their solubility in the pure solvent.

Principle of Chromatography

The chromatography principle is that “a mixture is applied to the surface or into a solid, and the fluid stationary phase (stable phase) separates from each other while moving with the help of the mobile phase”.

How to Separate Components from Black Ink

1. A thin strip of filter paper is cut out and a line is drawn 3 cm above the lower end of the filter paper. This is referred to as the reference line.
2. In the centre of the drawn line, a small dot of black ink is placed.
3. When the dot of black ink is dry, it is lowered into the water-filled chromatography jar.
4. The filter paper should be immersed so that the black ink dot is above the water level in the jar.
5. The setup should be left alone for a while.
6. The component of black ink that is more soluble in the water rises faster and higher up on the filter paper as the water begins to rise from the lower end of the filter paper. The level to which water rises is referred to as the waterfront.
7. Some coloured spots are observed corresponding to the separated components of the black ink, depending on the number of components present in the black ink.

Summary

The sample mixture is dissolved as the solvent rises through the paper, and it then travels up the paper. Because of differences in solubility and attraction to paper, smaller particles travel further than larger particles.

Frequently Asked Questions

1. What are the advantages of Chromatography?

Ans. The advantages of chromatography:

1. A very small quantity of the substance can be separated.
2. Components with very similar physical and chemical properties can be separated.
3. It defines the different constituents of a mixture.
4. It also helps in the quantitative estimation of components of a mixture.

2. What do you mean by Heterogeneous solution?

Ans. A heterogeneous mixture can be defined as a solution with a non-uniform composition, such as dye, milk, and sand water solution.  

3. What are the different types of dyes?

Ans. The natural dyes are henna, walnut shells, turmeric, and catechu. Some synthetic dyes are methyl orange, methyl red, congo red, malachite green, rosaniline, pararosaniline, crystal violet, phenolphthalein, indigo, fluorescein, and anthraquinone dye.