Q65 of 65 Page 26

Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals?

When carbonate ore (ore A) is heated, it produces carbon dioxide. A carbonate ore undergoes calcination to give metal oxide. For example, zinc carbonate undergoes calcination to give zinc oxide.


ZnCO3 → ZnO + CO2


When a sulphide ore (ore B) is heated, it produces sulphur dioxide. A sulphide ore undergoes roasting to give metal oxide. For example, zinc sulphide undergoes roasting to give zinc oxide.


2ZnS + 3O2→ 2ZnO + 2SO2


After calcination or roasting, zinc oxide should be reduced to obtain zinc. ZnO is a white powdery substance and is insoluble in water.


2ZnO + C → 2Zn + CO2


More from this chapter

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61

Explain the following.

(a) Reactivity of Al decreases if it is dipped in HNO3


(b) Carbon cannot reduce the oxides of Na or Mg.


(c) NaCl is not a conductor of electricity in solid state whereas it does conduct electricity in aqueous solution as well as in molten state.


(d) Iron articles are galvanised.


(e) Metals like Na, K, Ca and Mg are never found in their free state in nature.

 62

(i) Given below are the steps for extraction of copper from its ore. Write the reaction involved.

(a) Roasting of copper (I) sulphide


(b) Reduction of copper (I) oxide with copper (I) sulphide.


(c) Electrolytic refining


(ii) Draw a neat and well labelled diagram for electrolytic refining of copper.

 63

Of the three metals X, Y and Z. X reacts with cold water, Y with hot water and Z with steam only. Identify X, Y and Z and also arrange them in order of increasing reactivity.

 64

An element A burns with golden flame in air. It reacts with another element B, atomic number 17 to give a product C. An aqueous solution of product C on electrolysis gives a compound D and liberates hydrogen. Identify A, B, C and D. Also write down the equations for the reactions involved.