Write the chemical equations for the $Van$ $Arkel$ method used for the refining of $Zr$ and $Ti$.

(N/A) The $Van$ $Arkel$ method is used for refining metals like $Zr$ and $Ti$. The process involves two main steps:
$1$. The crude metal is heated in an evacuated vessel with iodine to form a volatile metal iodide:
$Zr(s) + 2I_2(g) \rightarrow ZrI_4(g)$
$Ti(s) + 2I_2(g) \rightarrow TiI_4(g)$
$2$. The metal iodide is decomposed by heating over a tungsten filament at a higher temperature $(1800 \ K)$ to obtain pure metal:
$ZrI_4(g) \rightarrow Zr(s) + 2I_2(g)$
$TiI_4(g) \rightarrow Ti(s) + 2I_2(g)$