General Principles And Processes of Isolation Of Elements

General Principles And Processes of Isolation Of Elements

Question

Outline the principles of refining of metals by the following methods: 

(i) Zone refining

(ii) Vapour phase refining

Answer

Principles of refining of metals by:

(i) Zone refining: The impurities are more soluble in the melt than in the solid state of the metal. Hence, the pure metal crystallises out of the melt and impurities pass on into the adjacent molten zone and like this at one end impurities get concentrated. Silicon, indium, boron, gallium etc. can be purified by this process.

(ii) Vapour phase refining: Vapour phase refining is the process of refining metal by converting it into its volatile compound and then, then decomposing it to obtain a pure to carry out this process

(a) The metal should form a volatile compound with an available reagent.

(b) The volatile compound should be easily decomposable so that the metal can be easily recovered.

Nickel, Zirconium, and titanium are using this method.

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