Question

Give scientific reasons for: Zinc oxide can be reduced to zinc by using carbon monoxide, but aluminium oxide cannot be reduced by a reducing agent.

August 19, 2024

Answer

Metals like Zinc are less electropositive and have less affinity for oxygen, hence their oxides like ZnO can be reduced by reducing agents like CO. Metal like Aluminium on the other hand are most electropositive and have strong affinity for oxygen. Hence, their oxides like aluminium oxide cannot be reduced by a reducing agent.

Some Related Questions

Metallurgy

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.

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

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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

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

Metallurgy

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

Metallurgy

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

Metallurgy

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

Metallurgy

Define (a) alloy (b) amalgam

Metallurgy

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.

Metallurgy

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