Q17 of 47 Page 1

Write down the reactions taking place in blast furnace related to the metallurgy of iron in the temperature range 500 K – 800 K. What is the role of limestone in the metallurgy of iron?

OR


What happens when


a. Silver is leached with NaCN in the presence of air?


b. Copper matte is charged into silica lined converter and hot air blast is blown?


c. NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method?


At 500 - 800 K, the reactions taking place are:
3Fe2O3 + CO →→ 2Fe3O4 + CO2
Fe3O4 + 4CO →→ 3 Fe + 4 CO2
Fe2O3 + CO →→ 2FeO + CO2
Limestone decomposes to CaO and CO2.
CaO combines with impurity (i.e.) SiO2 to form slag which is then removed.
CaO + SiO2→→ CaSiO3


OR


a. When silver is leached with NaCN in the presence of air it forms complex [Ag( CN)2]-


b. When copper matte is charged into silica lined converter and hot air blast is blown FeS undergoes roasting to FeO, which combines with SiO2 to form slag whereas Cu2S on roasting gives Cu2O which on reduction gives Cu.


c. When NaCN is added in an ore containing PbS and ZnS during concentration by froth floatation method it selectively prevents the ZnS from coming to the froth i.e., It acts as Depressant.


More from this chapter

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15

a. An element crystallises in bcc lattice with a cell edge of 3×10-8 cm. The density of the element is 6.89 g cm-3. Calculate the molar mass of the element. (NA = 6.022 ×× 1023 /mol)

b. What type of semiconductor is obtained when


i. Ge is doped with In?


ii. Si is doped with P?


 16

A solution 0.1 M of Na2SO4 is dissolved to the extent of 95%. What would be its osmotic pressure at 27oC? (R = 0.0821 L atm K-1 mol-1)

 18

Give reasons for the following:

a. Dioxygen is a gas but sulphur a solid.


b. NO (g) released by jet aeroplanes is slowly depleting the ozone layer.


c. Interhalogens are more reactive than pure halogens.


 19

Write the structures of monomers used to obtain the following polymers:

a. Neoprene


b. PHBV


c. Bakelite


OR


a. Arrange the following polymers in decreasing order of their intermolecular forces :
Bakelite, Polythene, Buna-S, Nylon-6,6


b. Write the monomers of the following polymer :


c. What is the structural difference between high density polythene (HDP) and low density polythene (LDP)?