Outline the principles of refining of metals by the following methods: (i) Zone refining (ii) Vapour phase refining

Zone refining: This method is based on the principle that impurities are more soluble in the metal’s melt than in its solid state.

Vapour phase refining: In this method, crude metal is purified of impurities by first converting it into a suitable volatile compound at a lower temperature by treating it with a specific reagent, and then decomposing the volatile compound at a higher temperature to yield pure metal.