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प्रश्न
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.
(a) When bauxite is treated with sodium hydroxide solution, what happens to:
(i) the aluminium oxide?
(ii) The iron (III) oxide?
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उत्तर
(i) Aluminium oxide being an amphoteric oxide reacts with sodium hydroxide solution to form soluble sodium meta aluminate.
\[\ce{\underset{\text{Alumina}}{Al2O3.2H2O} + 2NaOH + 2H2O ->\underset{\text{Sodium aluminate}}{2NaAIO2} + 3H2O}\]
(ii) Iron (III) oxide remains undissolved in the sodium hydroxide solution and settles down.
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संबंधित प्रश्न
Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
An element L consists of molecules.
When L is heated with iron metal, it forms a compound, FeL. What chemical term would you use to describe the change undergone by L?
Give reason for the following:
Carbon anodes are used in the electrolytic extraction of aluminium.
Give equation for the following conversion: Aluminium hydroxide to aluminium oxide.
Name oxide of one metal which is reduced by (give equation): Reduction with carbon
Give the chemical name and formula of ‘cryolite’.
what is the function of cryolite in the extraction of aluminium, other than acting as a solvent for bauxite?
Name a non-metallic element which is a liquid at ordinary temperatures
If fused metallic chloride is electrolyzed, at which electrode would the metal be obtained?
- A to F below relate to the source and extraction of either zinc or aluminium:
- Bauxite
- Coke
- Cryolite
- Froth floatation
- Sodium hydroxide solution
- Zinc blende
- Write down the three letters each from the above list which are relevant to
- Zinc
- Aluminium
- Fill in the blanks using the most appropriate words from A to F.
- The ore from which aluminium is extracted must first be treated with ………………. so that pure aluminium oxide can be obtained.
- Pure aluminium oxide is dissolved in ….. to make a conducting solution.
iii. Write the formula of cryolite.
