Question

Q.11. Write chemical equations for the reactions taking place
when :
(i) iron is strongly heated in air.
(ii) lead carbonate is calcined.
(iii) chromium oxide (Cr203) is heated with
aluminium powder.​

Answer 1

1. When iron metal is 'strongly heated' in air, iron oxide is formed.

4 Fe + 3O2 = 2Fe2O3

4 Fe + 3O2 = 2Fe2O3 3Fe + 2O2 = Fe3O4

2. The products of calcination of lead carbonate are lead oxide and carbon dioxide gas.

PbCO3 (at high temperature)= PbO + CO2

3. Cr2O3 + 2Al. 2Cr + Al2O. 3

Chromium(III) oxide react with aluminum to produce chromium and aluminum oxide. This reaction takes place at a temperature near 800°C.