Metallurgy Archives - Page 5 Of 9

Write a balanced chemical equation for – (i) The formation of aluminium at the cathode, during the electrolysis of alumina. (ii) Action of heat on aluminium hydroxide.

(i) At cathode : 2Al3+ + 6e- ⟶ 2Al (ii) Conversion of Al(OH)3 - to pure alumina - heat on Al(OH)3 2Al (OH)3 Al2O3 + 3H2O

Name the process by which impure ore of aluminium gets purified, by a conc. soln. of an alkali.

Baeyer's Process

Name the most common ore of the metal aluminium from which the metal is extracted. Write the chemical formula of the ore.

Bauxite [Al2O3.2H2O]

Name the main component of the alloy – (i) Brass (ii) Duralumin

(i) Brass — Copper & Zinc (ii) Duralumin — Aluminium & Copper.

Fill in the blank with the correct choice given in the bracket –
The most common ore of iron is ……………[calamine/haematite]

The most common ore of iron is haematite.

Give one word or a phrase for the statement : The process by which sulphide ore is concentrated.

Froth flotation process Reason — Sulphide ores like ZnS and PbS are lighter than the impurities present. They are concentrated by froth flotation process.

Give a reason for : Alkali metals are good reducing agents.

Alkali metals have one electron in the outermost shell and hence during reactions they readily give the valence electron and get themselves oxidised. Hence, they are good reducing agents.

Complete the following by selecting the correct option from the choices given –
(i) The metal whose oxide, which is amphoteric, is reduced to metal by carbon reduction …………… [Fe/Mg/Pb/Al]
(ii) The divalent metal whose oxide is reduced to metal by electrolysis of its fused salt is …………… [Al/Na/Mg/K]

(i) The metal whose oxide, which is amphoteric, is reduced to metal by carbon reduction — Pb. (ii) The divalent metal whose oxide is reduced to metal by electrolysis of it's…

Answer the following questions with respect to the electrolytic process – in the extraction of aluminium.
(i) Identify the components of the electrolyte other than pure alumina and the role played by each.
(ii) Explain why powdered coke is sprinkled over the electrolytic mixture.

(i) Cryolite and fluorspar are components of the electrolyte. Addition of cryolite enhances the conductivity of the mixture since, pure alumina is almost a non-conductor of electricity. Addition of both…

Name the following :
(i) An alloy of lead and tin that is used in electrical circuits.
(ii) An ore of zinc containing its sulphide.
(iii) A metal oxide that can be reduced by hydrogen.

(i) Solder [fuse metal] (ii) Zinc blende [ZnS] (iii) Copper oxide (CuO)

Flash Education