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प्रश्न
Explain with reason:
In the electrolytic reduction of alumina, the graphite anode is gradually consumed.
Explain with reason:
Why the anode has to be replaced from time to time in this process?
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उत्तर
In the electrolytic reduction of alumina, the graphite (anode) is oxidised by oxygen to CO and further forms CO2, so it is consumed and has to be replaced from time to time.
\[\ce{2C + O2 -> 2CO}\]
\[\ce{2CO + O2 -> 2CO2}\]
संबंधित प्रश्न
Name the following:
A metal oxide that can be reduced by hydrogen.
Name the compound added to pure alumina to lower the fusion temperature during the electrolytic reduction of alumina.
Write a balanced chemical equation for each of the following reactions :
(i) Reduction of copper (II) oxide by hydrogen
Give equation for the following conversion: Aluminium hydroxide to aluminium oxide.
what is the function of cryolite in the extraction of aluminium, other than acting as a solvent for bauxite?
Write balanced equation for the following reaction:
Reduction of copper oxide by hydrogen.
What is the type of bonding expected in a metallic chloride?
Answer the following question :
Name the process used for the enrichment of sulphide ore.
- 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.
The following sketch represents the electroplating of an Iron cup with Nickel metal.
Study the diagram and answer the following questions:
- During electroplating, the iron cup is placed at the cathode. Why?
- Name the ion that must be present in the electrolyte.
- State one condition that is necessary to ensure that the deposit is smooth, firm and even.
- Write the reaction taking place at the cathode.
- What change would you observe at the anode?
