Advertisements
Advertisements
प्रश्न
In the extraction of aluminium: Why is it necessary to replace anodes time to time?
Advertisements
उत्तर
The anode is replaced from time to time because it gets oxidised by oxygen which evolves at it.
APPEARS IN
संबंधित प्रश्न
What chemical process is used for obtaining a metal from its oxide?
Explain why, carbon cannot reduce oxides of sodium or magnesium.
Name one metal which is extracted by reduction with aluminium.
Fill in the following blank with suitable word:
The non-metal present in steel is ............
Name the gas produced when calamine ore is calcined.
Name two metals which are always found in combined state.
How is aluminium metal extracted? Explain with the help of an equation.
Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae.
Which of the following metals can be obtained from haematite ore?
(a) copper
(b) sodium
(c) zinc
(d) iron
A sulphide ore is converted into metal oxide by the process of:
(a) carbonation
(b) roasting
(c) calcination
(d) anodising
Which metal can be extracted from the following ore?
bauxite
What is galvanized iron.
Complete the incomplete statement with missing word:
Non-metals form acidic oxides while metals form ______.
Which one of the following is not true of metal :
Metals are good conductors of electricity.
Name the process used for the enrichment of sulphide ore.
Aluminium oxide is _______ oxide.
In the electrolytic method, a layer of highly active metal is applied to a less active metal.
Explain the following reaction with the balanced equation.
Zinc oxide is treated with carbon
Observe the figure and answer the following.
- Write the name of the method.
- What is used as anode and cathode in this method?
- Write the molecular formula and use of cryolite.
- Write anode reaction.
- Write cathode reaction.
On the basis of reactivity metals are grouped into three categories:
- Metals of low reactivity
- Metals of medium reactivity
- Metals of high reactivity
Therefore metals are extracted in pure form from their ores on the basis of their chemical properties.
Metals of high reactivity are extracted from their ores by electrolysis of the molten ore.
Metals of low reactivity are extracted from their sulphide ores, which are converted into their oxides. The oxides of these metals are reduced to metals by simple heating.
(a) Name the process of reduction used for a metal that gives vigorous reaction with air and water both.
(b) Carbon cannot be used as a reducing agent to obtain aluminium from its oxide? Why?
(c) Describe briefly the method to obtain mercury from cinnabar. Write the chemical equation for the reactions involved in the process.
OR
(c) Differentiate between roasting and calcination giving chemical equation for each.
