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प्रश्न
Explain in brief types of extraction of less reactive metals according to their reactivity.
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उत्तर
Extraction of less reactive metals:
- Less reactive metals such as gold, silver, platinum are found in a free state in nature.
- However, the reserves of copper in the free state are very few. It is found mainly in the form of Cu2S. Copper is obtained from Cu2S ore just by heating in the air.
\[\ce{\underset{\text{sulphide}}{\underset{\text{Copper(I)}}{2Cu2S_{(s)}}} + \underset{\text{Oxygen}}{3O_{2(g)}} ->[Heat] \underset{\text{oxide}}{\underset{\text{Copper(I)}}{2Cu2O_{(s)}}} + \underset{\text{dioxide}}{\underset{\text{Sulphur}}{2SO2\uparrow}}}\]
\[\ce{\underset{\text{Copper(I) sulphide}}{Cu2S_{(s)}} + \underset{\text{Copper(I) oxide}}{2Cu2O_{(s)}} ->[Heat] \underset{\text{Copper}}{6Cu_{(s)}} + \underset{\text{Sulphur dioxide}}{SO_2\uparrow}}\] - The copper metal thus obtained can be further refined electrolytically.
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संबंधित प्रश्न
How are the less reactive metals (which are quite low in the reactivity series) extracted? Explain with the help of an example.
Explain giving equation, what happens when:
A mixture of Cu2O and Cu2S is heated.
Explain why, an aqueous solution of sodium chloride is not used for the electrolytic extraction of sodium metal.
Name the chemical compound which is electrolysed in molten state to obtain sodium metal. Which gas is produced in this process?
What is the difference between a mineral and an ore?
Which metal is extracted from bauxite ore?
Explain how, mercury is extracted from its sulphide ore (cinnabar). Give equations of the reactions involved.
The two metals which are extracted by means of electrolytic reduction of their molten salts are ______.
Calamine ore can be used to extract one of the following metals. This metal is:
A sulphide ore is converted into metal oxide by the process of ______.
Distinguish between ‘roasting’ and ‘calcination’. Which of these two is used for sulphide ores and why?
Give the chemical formula of :
Cryolite
Compare the process of calcination and roasting.
What is meant by refining of metals? Name the three common methods used for refining.
To protect iron from rusting, it is coated with a thin layer of zinc. Name the process.
Calcium, copper, lead, aluminium, zinc, chromium, magnesium, iron.
Choose the major metals from the list given above to make the following alloys:
(a) Stainless steel
(b) brass
Zinc blende is converted to oxide by ______ process.
Observe the given figure of reactivity series of metals and answer the following questions:
Reactivity series of metals
- Name two metals which react with water.
- Name two moderately reactive metals.
- Name the most highly reactive metal and the most less reactive metal.
Write the molecular formulae of the following compound.
Cryolite
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.
