Question

State (i) composition (ii) reason for alloying (iii) one use of each of the following alloys.
(i) Brass
(ii) Bronze
(iii) Duralumin
(iv) Solder [fuse metal]
(v) Stainless steel

August 22, 2024

Answer

Alloy	Composition	Reason for alloying	Use
1. Brass	Cu [60 – 80%], Zn [40 – 20%]	Hard, Lustrous, easily cast, malleable, ductile	Electrical fittings, decorative articles
2. Bronze	Cu [80%], Zn [1%], Sn [19%]	Hard, brittle, takes up polish	Statues, medals, coins
3. Duralumin	Al [95%], Mg [0.5%], Mn [0.5%], Cu [4%]	Al – imparts lightness, Mg – imparts strength	Aircrafts, light tools, cooker
4. Solder [fuse metal]	Pb [50%], Sn [50%]	Sn – lowers melting point of alloy	Electrical fuse, Soldering purposes
5. Stainless steel	Fe [75%], Ni [10%], Cr [15%], C [.5%]	Ni, Cr – imparts lustre, C – imparts hardness	Utensils, cutlery, surgical instruments

💡 Some Related Questions

Name the following : (i) A metallic ore converted to it’s oxide – iron [II] oxide on heating the concentrated ore.
(ii) A black metallic oxide reduced to metal on heating with coke.
(iii) The compound which on ignition at elevated temperatures gives pure alumina.
(iv) The non-metal which forms the anode during electrolytic reduction of fused alumina in Hall Heroult’s process.
(v) A metal other than manganese, present in duralumin but not in magnalium.

The metallic oxide reduced to metal generally by thermal decomposition.
(a) ZnO
(b) MgO
(c) HgO
(d) Al2O3

The process of dressing of the ore which involves separation of ore & gangue due to preferential wetting.
(a) Magnetic separation
(b) Hydrolytic method
(c) Froth flotation method
(d) Chemical method

The chemical name of the main ore of aluminium.
(a) Aluminium fluoride
(b) Aluminium oxide
(c) Sodium aluminium fluoride
(d) Hydrated aluminium oxide

The common name of the ore of iron whose chemical formula is Fe3O4.
(a) Iron pyrites
(b) Magnetite
(c) Haematite
(d) Spathic iron ore

The oxide of the metal which reacts with both acids and alkalis to give salt & water.
(a) MgO
(b) CuO
(c) Al2O3
(d) K2O

Define (a) alloy (b) amalgam

Give reasons for the following pertaining to Hall Herault’s process.
(i) The fusion temperature of the electrolyte has to be lowered before conducting the electrolytic reduction.
(ii) The constituents of the electrolyte in addition to one part of fused alumina contains three parts of cryolite and one part of fluorspar.
(iii) A layer of powdered coke sprinkled over the electrolytic mixture, protects the carbon electrodes.
(iv) It is preferred to use a number of graphite electrodes as anode, instead of a single graphite electrode.

State the function of (i) Sodium hydroxide (ii) Cryolite (iii) Fluorspar in the metallurgy of aluminium in Hall Herault’s process.

In the electrolytic reduction of pure alumina to pure aluminium by Hall Herault’s process, give the electrolytic reactions involved in the same, resulting in formation of aluminium at the cathode.