We know that this method is also known as vapour phase refining.
This method is based on the fact that certain metals are converted to their volatile compounds while impurities are not affected during compound formation.
Volatile compounds are compounds that have a relatively higher than normal vapour pressure at room temperature, these compounds are the most likely to easily escape into the air as a gas at the slightest energy provided. Some examples of volatile compounds are benzene, toluene, formaldehyde, alcohols, etc.
Van Arkel method is used for getting ultra pure metal. In this method, metal is converted to volatile unstable compounds taking care that impurities are not affected.
The volatile unstable compound thus obtained is decomposed to get the pure metal.
This method is used for the purification of metals like titanium and zirconium.
