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प्रश्न
For sodium hydroxide, explain its significance in the extraction of aluminium.
उत्तर १
The ore from which aluminium is extracted must first be treated with sodium hydroxide solution so that pure aluminium oxide can be obtained.
उत्तर २
Sodium hydroxide (NaOH) dissolves bauxite to form sodium meta-aluminate, removes soluble impurities and gives \[\ce{Al(OH)3↓}\] from which \[\ce{Al2O3}\] is obtained by heating.
\[\ce{Al2O3.2H2O + 2NaOH -> 2NaAlO2 + 3H2O}\]
\[\ce{NaAlO2 + 2H2O -> NaOH + Al(OH)3↓}\]
\[\ce{2Al(OH)3 ->[heat][1000^\circ C] Al2O3 + 3H2O}\]
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संबंधित प्रश्न
Aluminium is said to be more reactive than iron, towards oxygen (or air) yet iron undergoes corrosion to a greater extent than aluminum. Explain.
For cryolite, explain its significance in the extraction of 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 ?
Name the following:
The materials used as electrodes in the electrolytic extraction of aluminium.
For the substance listed below, explain its role in the extraction of aluminium: Bauxite
For the substance listed below, explain its role in the extraction of aluminium: Sodium hydroxide
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.
Name the alloy used for the following purpose.
Making parts of watches
Fused alumina is reduced to aluminium by electrolytic reduction, since ______.
State true or false.
Bauxite is the main ore of aluminium.
