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प्रश्न
Describe the role played in the extraction of aluminum:
Sodium hydroxide
उत्तर
In the extraction of aluminium, the given compounds play the following roles:
Sodium hydroxide :
Two roles are played by sodium hydroxide in the extraction of aluminium.
First, finely grinded bauxite (ore of aluminium) is heated under pressure with conc. caustic soda solution (NaOH solution) for 2-8 hours at 140°C to 150°C to produce sodium aluminate. The chemical equation is as follows:
Al2O3.2H2O + 2NaOH → 2NaAlO2+ 3H2O
Second, on diluting sodium aluminate with water and cooling to 50°C, sodium aluminate is hydrolysed to give aluminium hydroxide as a precipitate. Here, the impurities dissolve in sodium hydroxide.
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संबंधित प्रश्न
Give the chemical names and formulae of the main ores of zinc.
Name the constituents of Brass.
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?
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Write an equation for the reaction which takes place at the anode during the extraction of aluminium by the electrolytic process.
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In order to obtain one tone of aluminium, the following inputs are required:
4 tones 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 (II) oxide. Aluminium is obtained by the electrolysis of aluminium oxide dissolved in cryolite.
In construction work, why is the alloy of aluminium, duralumin used rather than pure aluminium.
The following question relate to the extraction of aluminium by electrolysis.
Name the other aluminium containing compound added to alumina and state the significance.
During the concentration of bauxite ore, aluminium goes in ______ part because of its ______ nature.
Given below in column A is a schematic diagram of the electrolytic reduction of alumina. Identify the parts labelled as A, B and C with the correct options from the Column B.
| column A | column B | |
 |
1. | Platinum |
| 2. | Anode | |
| 3. | Cathode | |
| 4. | Electrolyte mixture | |
| 5. | Bauxite |
