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प्रश्न
For cryolite, explain its significance in the extraction of aluminium.
उत्तर
Lowers the fusion temperature from 2050°C to 950°C and enhances conductivity.
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संबंधित प्रश्न
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?
Aluminium is extracted from its chief ore, bauxite. The ore is first purified and then the metal is
extracted from it by electrolytic reduction
Mention one reason for the use of aluminium in thermite welding ?
Give reason for the following:
Extraction of aluminium was very difficult in the beginning.
How is ore purified (give equations also)
The following is an extract from 'Metals in the Service of Man, Alexander and Street/Pelican 1976':
| 'Alumina (aluminium oxide) has a very high melting point of over 2000°C so that it cannot readily be liquefied. However, conversion of alumina to aluminium and oxygen, by electrolysis, can occur when it is dissolved in some other substance.' |
- Which solution is used to react with bauxite as a first step in obtaining pure aluminium oxide?
- The aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide. Write the balanced chemical equation for this reaction.
- Name the element which serves both as the anode and the cathode in the extraction of aluminium.
- Write the balanced chemical equation for the reaction that occurs at the cathode during the extraction of aluminium by electrolysis.
- Give the balanced chemical equation for the reaction which occurs at the anode when aluminium is purified by electrolysis.
Write the equation for the reaction where the aluminium oxide for the electrolytic extraction of aluminium is obtained by heating aluminium hydroxide.
Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
Write the equation for the reaction that occurs at the cathode during the extraction by aluminium by electrolysis.
Name the alloy used for the following purpose.
Making medals
