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प्रश्न
Explain the concept of Roasting.
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उत्तर
In roasting process, the sulphide ores are strongly heated in air to transform them into oxides. In this process, sulphide ores are oxidized to form metal oxides and sulphur dioxide gas.
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संबंधित प्रश्न
Name two metals which are found in nature in the free state.
Give reasons.
Aluminium is a highly reactive metal, yet it is used to make utensils for cooking.
In the extraction of aluminium Write the cathode reaction in electrolytic reduction of alumina.
Define the term ore.
Name three other metals which are extracted in a manner similar to sodium.
Name the electrode at which aluminium metal is produced.
The metal which can be extracted from the bauxite ore is:
(a) Na
(b) Mn
(c) Al
(d) Hg
The metal which can be extracted from pyrolusite ore is:
(a) mercury
(b) manganese
(c) aluminium
(d) magnesium
Give the principles of the froth floatation process.
Give reasons, why aluminum is used in:
making alloys
Name the anode, the cathode and the electrolyte used in the electrolytic refining of impure copper.
Give the chemical formula of :
Sodium aluminate
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
Which one of the following is not true of metal :
Metals are malleable and ductile
Froth floatation process is generally used to concentrate ______ ores.
The poorest conductor of heat among metals is ____________.
The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called ____________.
An alloy is
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.
Assertion (A): The extraction of metals from their sulphide ores cannot take place without roasting the ore.
Reason (R): Roasting converts sulphide ores directly into metals.
