Ask a Teacher

Search



what is vapour phase refining?
Vapour phase refining
In this method, the metal is converted into its volatile compound and collected elsewhere. It is then decomposed to give pure metal. So, the two requirements are:
(i) the metal should form a volatile compound with an available reagent,
(ii) the volatile compound should be easily decomposable, so that the recovery is easy.

This method is very useful for removing all the oxygen and nitrogen present in the form of impurity in certain metals like Zr and Ti. The crude metal is heated in an evacuated vessel with iodine. The metal iodide being
more covalent, volatilises:
Zr + 2I2 ? ZrI4
The metal iodide is decomposed on a tungsten filament, electrically heated to about 1800K. The pure metal is thus deposited on the
filament.
ZrI4 ? Zr + 2I2


comments powered by Disqus