Question

Which metal is refined by Van-Arkel method?
A. $Ni$
B. $Al$
C. $Si$
D. $Ti$

Answer 1

Hint: In order to answer the question, first we have to know why the Van-Arkel method is used and then discuss the whole process of usage of the Van-Arkel’s Method. Zirconium is also refined by this Van-Arkel Process.

Complete answer:
Ti or Zr metal is refined by the Van-Arkel method. Metal is converted (by heating with little iodine) to volatile (covalent) tetraiodide which is then decomposed (by electrically heating above \[1800K\] with tungsten filament ) to pure metal which is deposited on a tungsten filament.
With the help of the Van-Arkel Method, ultra pure metals are being prepared. This method is based on the thermal decomposition of metal components. In this method, the crude metal is heated with suitable substances then the pure metal present in it is converted into stable volatile compounds leaving impurities behind. And the formed compound is then decomposed by heating to get the pure metal. Van-Arkel method is used to purify crude titanium metal by heating the titanium metal with iodine to about $500K$ to form volatile compounds. And the heated compound $TiC{l_4}$ leaving behind the impurities. $TiC{l_4}$ is further heated to $1700K$ when it decomposes to give pure titanium. This process is also known as Crystal Bar Process.
Hence, the correct option is (D) $Ti$.

Note: The titanium is also purified by high temperature vacuum distillation. The metal is in the form of a porous granule which is called sponge. This may be processed on site, or sold on to other companies for conversion to titanium products.