Question

Write the principle of vapour phase refining.

Answer 1

Vapour phase refining

It is a refining method used in metallurgy in which impure metal is converted into its volatile compound and collected elsewhere.

It is then decomposed to give pure metal.

For example:

1. Mond's process is used for Nickel (Ni).

2. Van Arkel method, which is used for Zirconium (Zr).

The equation for Mond's process:

$\mathrm{Ni}+4\mathrm{CO}\stackrel{330-350\mathrm{K}}{\to }$$\mathrm{Ni}{\left(\mathrm{CO}\right)}_4$

$\mathrm{Ni}{\left(\mathrm{CO}\right)}_4$$\stackrel{450-470\mathrm{K}}{\to }$$\mathrm{Ni}+4\mathrm{CO}$

The equation for Van Arkel Method

$\mathrm{Ti}\left(\mathrm{s}\right)\left(\mathrm{Impure}\right)+2{\mathrm{I}}_2$$\left(\mathrm{g}\right)\stackrel{523\mathrm{K}}{\to }$${\mathrm{TiI}}_4$$\left(\mathrm{g}\right)$

${\mathrm{TiI}}_4$$\left(\mathrm{g}\right)\stackrel{1700\mathrm{K}}{\to }$$\mathrm{Ti}\left(\mathrm{s}\right)+2{\mathrm{I}}_2$$\left(\mathrm{g}\right)\left(\mathrm{pure}\right)$