Answer the following questions briefly.(i) What is the actual reducing agent of haematite in blast furnace?(ii) Give the equations for the recovery of lead from galena by air reduction(iii) Why is sodium chloride added during electrolysis of fused anhydrous magnesium chloride?(iv) Zinc, not copper, is used for the recovery of metallic silver from the complex [Ag(CN)2]−, explain.(v) Why is chalcocite roasted and not calcinated during recovery of copper?

Question

Answer the following questions briefly.(i) What is the actual reducing agent of haematite in blast furnace?(ii) Give the equations for the recovery of lead from galena by air reduction(iii) Why is sodium chloride added during electrolysis of fused anhydrous magnesium chloride?(iv) Zinc, not copper, is used for the recovery of metallic silver from the complex [Ag(CN)2​]−, explain.(v) Why is chalcocite roasted and not calcinated during recovery of copper?

Filo · Accepted Answer

(i)For iron, first by calcination and roasting, the ferrous oxide is oxidized to ferric oxide. Then, in blast furnace, smelting is done, where it is reduced to get iron.4FeO+O2​→2Fe2​O3​Fe2​O3​+CO→2Fe3​O4​+CO2​Fe2​O3​+CO→FeO+CO2​FeO+CO→Fe+CO2​Carbon monoxide is the actual reducing agent of hematite in the blast furnace.(ii)Lead is mainly extractd from sulphide ore called galena. Roasting is done followed by reduction with carbon. Self-reduction finally takes place.2PbS+3O3​→2PbO+SO2​PbS+2O2​→PbSO4​PbSO4​+PbO→2Pb+2SO2​PbS+2PbO→3Pb+SO2​(iii) The anhydrous magnesium chloride is fused with NaCl and anhydrous calcium chloride. The mixture is electrolyzed at 7000C in the presence of an inert gas i an electrolytic cell. Magnesium is discharged at the cathode. The purpose of the addition of NaCl and CaCl2​ to anhydrous MgCl2​ is to lower the fusion temperature and make the fused mass a good conductor of electricity. Sodium chloride prevents the hydrolysis of magnesium chloride.(iv) Zinc is more reducing and cheaper than copper.(v)Chalcocite is a sulphide ore of copper; therefore, it muxst be roasted in the presence of air to get oxide.

Question Text	Answer the following questions briefly. (i) What is the actual reducing agent of haematite in blast furnace? (ii) Give the equations for the recovery of lead from galena by air reduction (iii) Why is sodium chloride added during electrolysis of fused anhydrous magnesium chloride? (iv) Zinc, not copper, is used for the recovery of metallic silver from the complex $[A g (CN)_{2}]^{-}$ , explain. (v) Why is chalcocite roasted and not calcinated during recovery of copper?
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