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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.
When bauxite is treated with sodium hydroxide solution, what happens to:
- the aluminium oxide,
- the iron (III) oxide?
उत्तर
- The aluminium oxide forms sodium aluminate.
\[\ce{Al2O3.2H2O + 2NaOH ->[150^\circ C - 200^\circ C] 2NaAlO2 + 3H2O}\] - The iron (III) oxide does not dissolve in NaOH and is removed by filtration.
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संबंधित प्रश्न
For the substance given below, describe the role played in the extraction of aluminium.
Graphite
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?
The reason for using Aluminium in the alloy duralumin is ______.
Name the ore from which aluminium is extracted.
In the Hall's process for extraction of aluminium, Give the formula and purpose of fluorspar and cryolite
In the Hall's process for extraction of aluminium, Sate the location of cathode and anode and explain what occurs at each electrode.
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.
The following question relate to the extraction of aluminium by electrolysis.
Name the other aluminium containing compound added to alumina and state the significance.
Name the compound formed when: Bauxite reacts with sodium hydroxide.
The compound that is not an ore of aluminum is ______.
