Question

What is meant by the term chromatography?

Answer 1

Hint: The chromatography is based on two words. This is used for the separation of coloured substances found in plants.it is also used for the purification of compounds.

Complete step by step answer:
The chromatography term is based on two words chroma meaning colour and graphy meaning writing. So, the chromatography is used to separate the coloured compounds, purify and to test the purity of compounds.
The technique of chromatography is based on the difference in the rates at which the components of a mixture move through a porous medium called the stationary phase under the influence of some solvent or gas which is called the moving phase. Thus, this technique consists of two phases-one of these is a stationary phase of a large surface area while the second is a moving phase which is allowed to move slowly over the stationary phase. The stationary phase is either a solid or a liquid while the moving phase may be liquid or a gas.
Based on the principle involved, chromatography is classified into two categories as
Adsorption chromatography-it is based on the fact that different compounds are adsorbed on an adsorbent to different degrees.
Partition chromatography-it is based upon the differences in the tendencies of substances to distribute between two phases.

Note:
Adsorption is the phenomenon of higher concentration of molecular species on the surface of solid than in the bulk.
The substance which gets adsorbed on the solid surface is known as adsorbate and the solid surface on which the substance is adsorbed is known as adsorbent.