Explain the following :
b) Thin layer chromatography

Explanation

Thin layer chromatography : This type of chromatography also involves adsorption difference. Here the absorbent silica gel or alumina is coated over a glass plate of suitable size. The plate is called TLC plate or chromoplate. The solution of the mixture to be separated is applied as a small spot at about 2 cm from the bottom of the plate. The plate is then kept in a closed jar containing the eluant (solvent). As the eluant rises up the plate, teh componetns of the mixture move up along with the eluant to various distances depending on their degree of adsorption.
The relative adsorption of a component of the mixture is expressed in terms of its Retardation Factor `(R_(f))` value.
Distance moved by the `R_(f)=("substance from base line (X)")/("Distance moved by the solvent from the base line (Y)")`