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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
Give a reasons for the following:
Carbonate and sulphide ores are usually converted into oxides during the process of extraction of metals.
Why does a new aluminium vessel lose shine so soon after use?
Name two metals which are highly resistant to corrosion.
Name the gas produced when calamine ore is calcined.
Name two metals which are found in nature mainly in the free state (as metallic elements).
Name three other metals which are extracted in a manner similar to sodium.
Name one ore of aluminium. Name the aluminium compound present in this ore and write its chemical formula.
Name one ore of mercury. Which mercury compound is present in this ore? Write its chemical formula.
An ore of manganese metal is ______.
An important ore of zinc metal is ______.
Distinguish between ‘roasting’ and ‘calcination’. Which of these two is used for sulphide ores and why?
Define the following term.
Mineral
Name the following:
The process in which an ore is heated in air so that oxygen gets added to it to form the oxides.
Name the following:
The process of heating an ore to a high temperature in the presence of air.
If Cu, Fe, Zn, Al elements are arranged in increasing order of their reactivity then the correct order would be which of the following?
Explain in brief types of extraction of moderately reactive metals according to their reactivity.
Answer the questions on the following passage.
The minerals from which the metal can be separated economically are called ores. Ores contain many types of impurities such as soil, sand and rocky substances along with metal compounds. These impurities are called gangue.
Metals can be extracted from their ores by means of various methods of separation. The process of extraction of metal in a pure state from the ores is also a part of metallurgy.
Ores are taken out from the mines and the gangue is usually separated from the ore at the site itself by various methods. Then the ores are carried out to the place where metals are produced. Here metals are extracted in pure form. Then metals are further purified by different methods of purification. This entire process is called metallurgy. Most metals being reactive do not occur in nature in the free state but are found in combined state as their salts such as oxides, carbonates, sulphides, and nitrates. however, the most unreactive metals that are not affected by air, water and other natural factors like silver, gold, platinum, generally occur in a free state. The compounds of metals that occur in nature along with the impurities are called minerals.
- What are ores?
- Which processes are involved in the branch of metallurgy? What is metallurgy?
- Which metals are found in a free state?
- In what forms are metals found in combined state?
- What is gangue?
2 mL each of concentrated HCl, HNO3 and a mixture of concentrated HCl and concentrated HNO3 in the ratio of 3 : 1 were taken in test tubes labelled as A, B and C. A small piece of metal was put in each test tube. No change occurred in test tubes A and B but the metal got dissolved in test tube C respectively. The metal could be
Two ores A and B were taken. On heating ore A gives CO2 whereas, ore B gives SO2. What steps will you take to convert them into metals?
The given reaction shows one of the processes to extract the metals like Iron and Manganese.
\[\ce{MnO2(s) + Al(s) -> Mn(l) + Al2O3(s) + Heat}\]
Give the reason why the above reaction is known as a thermite reaction.
