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प्रश्न
State why aluminium is extracted from its oxide by electrolysis while copper, lead, iron by reducing agents and mercury and silver by thermal decomposition.
उत्तर
Aluminium has a great affinity for oxygen and so cannot be reduced by carbon or carbon monoxide. So, it is extracted from its oxide by electrolysis.
Metals like copper, lead, and iron are placed in the middle of the activity series and are moderately reactive, and carbon, CO and hydrogen can reduce their oxides. Mercury and silver are less reactive and are placed lower in the reactivity series. The oxides of these metals are reduced to metals by heating their oxides.
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संबंधित प्रश्न
Give reasons.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
How is zinc extracted from its carbonate or (calamine)? Explain with equations.
Give the name of one ore of iron. Which iron compound is present in this ore? Write its chemical formula.
Which of the following metals can be obtained from haematite ore?
(a) copper
(b) sodium
(c) zinc
(d) iron
Manganese metal is extracted from manganese dioxide by a reduction process by making use of:
(a) carbon
(b) hydrogen
(c) electrolysis
(d) aluminium
Name the following:
The mixture of materials fed into a furnace to extract a metal.
Define the term : Flux
Name the process used for the enrichment of sulphide ore.
Which of the following metals exist in their native state in nature?
- Cu
- Au
- Zn
- Ag
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.
