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प्रश्न
What is the difference between calcination and roasting?
Compare roasting and calcination.
Differentiate between calcination and roasting.
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उत्तर
| Roasting | Calcination | |
| (1) | The ore is heated in the excess of air. | The ore is heated in the absence of air. |
| (2) | Volatile impurities are removed as oxides (SO2, P2O5, As2O3) and the ore becomes porous and more reactive. | Moisture and organic impurities are removed and the ore becomes porous and more reactive. |
| (3) | Sulphide ores are roasted, so SO2 is given off. \[\ce{2ZnS + 3O2 ->[800^\circ-900^\circ C]2ZnO + 2SO2}\] |
Carbonate and hydrated ores are calcined and CO2 or water vapour are given off. \[\ce{ZnCO3 -> ZnO + CO2}\] |
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संबंधित प्रश्न
In the extraction of aluminium: Name the process of concentration of bauxite.
Define the Ore.
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The property possessed by metals by which they can be beaten into sheets.
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Define the term gangue.
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The major ore of aluminium is known as ______.
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- Name the metal oxide XO2.
- Which reducing agent can be used to reduce XO2 to obtain metal X?
- Name another metal which can also be extracted by the reduction of its oxide with the above reducing agent.
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painting electric and telegraphic poles
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What is galvanized iron.
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The Process of heating an ore to a high temperature in the presence of air.
Find the odd one out and give its explanation.
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(b) Suggest a suitable electrolyte also.
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On the basis of reactivity metals are grouped into three categories:
- Metals of low reactivity
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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.
