(i) Indicate the principle behind the method used for the refining of Zirconium.

(ii)What is the role of CO in the extraction of iron?

(iii)What is ‘copper matte’

(i) The method adopted for the refining of zirconium is called Van Arkel Method.

• The crude metal is heated in an evacuated vessel in the presence of iodine where the metal iodide being more covalent, volatises.

Zr + 2I₂ ZrI₄

• The metal iodide is decomposed on a tungsten filament, electrically heated at 1800K resulting in the pure metal depositing on the filament.

ZrI₄Zr + 2I₂

• An advantage of this method is that it is very useful in the removal of oxygen and nitrogen present as impurities in the metal.

(ii) CO acts as a reducing agent in the extraction of iron and also helps produce high temperature inside the furnace.

(iii) Copper matte contained Cu₂S and FeS.

• It is obtained by heating the copper ore in a reverberatory furnace after mixing with silica.

• When heated in the furnace, FeO gets removed as a slag as iron silicate and copper is produced in the form of copper matte.

FeO + SiO₂ FeSiO₃