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प्रश्न
Aluminium is a more active metal than iron, but suffers less corrosion. Why?
उत्तर
When aluminium is exposed to atmospheric air, it combines with oxygen, and a film of aluminium oxide (Al2O3) is formed at the surface. This hard, tightly adhering film prevents corrosion.
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संबंधित प्रश्न
Write the equation for the reaction where the aluminum oxide for the electrolytic extraction of aluminum is obtained by heating aluminum hydroxide.
In order to obtain 1 tonne of aluminium, the following inputs are required: 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.
- Name the process used for the purification of bauxite.
- Write the equation for the action of heat on aluminium hydroxide.
In order to obtain 1 tonne of aluminium, the following inputs are required: 4 tonnes of bauxite, 150 kg of sodium hydroxide and 600 kg of graphite. The aluminium compound in bauxite is aluminium oxide and the main impurity is iron (III) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.
- Write the formula of cryolite.
- Write down the word which correctly completes the following sentence.
By dissolving aluminium oxide in cryolite, a ______ (conducting/non-conducting) solution is produced. - Why is so much graphite required for the electrolytic process?
- Write the equation for the reaction which takes place at the cathode.
- What is cathode made up of?
Explain the following:
In construction work, why is the alloy of aluminium-duralumin used rather than pure aluminium?
Name the following:
The substance added along with aluminium in the Hall-Heroult's process.
Aluminium is extracted from its chief ore bauxite. The ore is first purified and then the metal is extracted from it by electrolytic reduction.
Write three balanced equations for the purification of bauxite by Hall's process.
The sketch below illustrates the refin ing of aluminium by Hoope's process
(a) Which of A and B is th e cathode and which one is the anode?
(b) What is the electroly te in the tank?
( c) What material is used for th e cathode?
The following question relate to the extraction of aluminium by electrolysis.
Explain why is it necessary to renew the anode periodically.
Name the solution used to react with bauxite as a first step in obtaining pure aluminium oxide, in the Baeyer's process.
Name the following:
A metal which is always present in the amalgam.
