Advertisements
Advertisements
प्रश्न
How is aluminium obtained from pure ore?
उत्तर
Aluminium is obtained from pure ore by Hall - Heroult's process as follows:
i. Electrolyte used :
a. Pure alumina
b. Cryolite
c. Aluminium fluoride
d. Calcium fluoride or Fluorspar
ii . Electrolytic cell : It is a rectangular steel tank with a thick inner lining of carbon .
iii . Electrodes used :
a. Cathode: inner lining of carbon
b. Anode: Thick carbon rods dipping into the fused electrolytes.
iv. Temperature of the electrolytic bath : 950°C
Reactions: On passage of electricity through electrolyte aluminium and oxide ions are formed.
At cathode: Aluminium ions get reduced as:
Al3+ + 3e- → Al
At anode: oxygen gas is liberated as:
O2- - 2e- → [ O ]
[ O ] + [ O ] → O2
The oxygen formed at anode oxidizes the carbon of the anode to carbon dioxide.
C + O2 → CO2
As a result the anode gets oxidized and it has to be replaced periodically.
Figure: Extraction of aluminium from pure ore.
APPEARS IN
संबंधित प्रश्न
Answer the following questions with respect to the electrolytic process in the extraction of aluminum:
Explain why powdered coke is sprinkled over the electrolytic mixture.
Explain the following:
In construction work, why is the alloy of aluminium-duralumin used rather than pure aluminium?
In the Hall's process for extraction of aluminium, Give the formula and purpose of fluorspar and cryolite
An aqueous solution of sodium chloride is not used for electrolytic reduction of sodium metal. Why?
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. Which particular property of cast iron makes it unsuitable for the construction of bridges?
The sketch below illustrates the refin ing of aluminium by Hoope's process
(a) Which of A and B is th e cathode and which one is the anode?
(b) What is the electroly te in the tank?
( c) What material is used for th e cathode?
Explain the reason:
Why 'food containing iron salts' should not be cooked in aluminium utensils?
State the relevant reason for the following:
A layer of powered coke is used over the electrolytic mixture in Hall Heroult’s process.
State the relevant reason for the following:
Graphite anodes are continuously replaced during the electrolysis of alumina.
What impurities are present in aluminium ore?
