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Question
Write the chemical equations involved in van Arkel method for refining zirconium metal.
Solution
This method is useful for removing impurities in the form of oxygen and nitrogen in metal like zirconium. The crude metal is heated in an evacuated vessel with iodine. The metal iodine volatilizes.
\[\ce{\underset{\text{Impure}}{Zr} + 2I2 -> \underset{\text{Vapour}}{ZrI4}}\]
The metal iodine is decomposed on tungsten filament, electrically heated to about 1800K. The pure metal is thus deposited on the filament
\[\ce{\underset{\text{Vapour}}{ZrI4} -> \underset{\text{Pure}}{Zr} + 2I2}\]
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