Outline the principples behind the refining of metals by the following methods :
(i) Zone refining method
(ii)Chormatographaphic method

Explanation

(i) Zore refining Method : Zone refining method is based on the principle that impurities are more soluble in the molten state then in the solid state of a metal. This method is used in the purification of elements like Germanium (Ge), Silicon (Si), Indium (In) etc.
(ii) Chromatography method : Chromatography is the technique used for separation of the compoenents of a mixture that are soluble in the same solvent and are differently adsorbed on an adsorbent. This teachnique was first used for separation of colurs and hence, the name. There are two phases in chromatography - the stationary phase and the mobile phase. The components of the mixture are absorbed differently in the stationary phase, thus leading to their separation. There are many different types of chromatography-paper chromatography, thin-layar chromatography, gas chromatography etc.