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प्रश्न
Define roasting.
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उत्तर
Roasting is the process of heating concentrated ore to a high temperature in the presence of air. The process is usually carried out for sulphide ores.
संबंधित प्रश्न
In the extraction of aluminium: Name the process of concentration of bauxite.
Write the steps involved in the extraction of pure metals in the middle of the activity series from their carbonate ores.
In the extraction of aluminium: Why is it necessary to replace anodes time to time?
A zinc ore gave CO2 on treatment with a dilute acid. Identify the ore and write its chemical formula.
Why do gold ornaments look new even after several years of use?
Explain why, carbon cannot reduce oxides of sodium or magnesium.
Bronze is an alloy of copper and ______.
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:
ZnCO3 is heated in the absence of air?
Which gas is produced during the extraction of aluminium? At which electrode is this gas produced?
Which metal is extracted from bauxite ore?
The major ore of aluminium is known as ______.
Which of the following pair of metals exists in their native state in nature?
State why aluminium is extracted from its oxide by electrolysis while copper, lead, iron by reducing agents and mercury and silver by thermal decomposition.
Give the chemical formula of :
Cryolite
The following question relate to the extraction of aluminium by electrolysis.
Give the equation for the reaction which takes place at the cathode.
To protect iron from rusting, it is coated with a thin layer of zinc. Name the process.
Correct the following statement :
Copper reacts with nitric acid to produce nitrogen dioxide.
State three objectives achieved during the roasting of ores.
_______ is the least reactive metal.
Write the name.
Metals which are amphoteric in nature.
In the electrolytic method, a layer of highly active metal is applied to a less active metal.
Explain the reactions of nonmetals with water with the help of examples.
Explain the following reaction with the balanced equation.
Dry aluminium hydroxide is ignited at 1000 °C
Observe the following diagram and write answers.
- Name the method.
- Write anode reaction and cathode reaction.
- Why fluorspar and cryolite are added in the mixture?
Explain in brief types of extraction of less 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?
The process in which a carbonate ore is heated strongly in the absence of air to convert it into metal oxide is called ____________.
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.
