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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
Name two metals which are found in nature in the free state.
In the electrolytic refining of a metal M, what would you take as the anode, the cathode and the electrolyte?
Give a reason for the following:
Carbonate and sulphide ores are usually converted into oxides during the process of extraction of metals.
A man went door to door posing as a goldsmith. He promised to bring back the glitter of old and dull gold ornaments. An unsuspecting lady gave a set of gold bangles to him which he dipped in a particular solution. The bangles sparkled like new but their weight was reduced drastically. The lady was upset, but after a futile argument, the man beat a hasty retreat. Can you play the detective to find out the nature of the solution he had used?
In the extraction of aluminium: Why is it necessary to replace anodes time to time?
Give two uses of bronze.
Why does a new aluminium vessel lose shine so soon after use?
Which metal is extracted from cinnabar ore?
Name two ores of zinc. Write the names of the chemical compounds present in them and give their chemical formulae.
How is copper extracted from its sulphide ore (copper glance), Cu2S? Explain with equations of the reactions involved.
Which of the following is an ore of mercury metal?
(a) rock salt
(b) cinnabar
(c) calamine
(d) haematite
Metals X and Y can be recovered from the anode mud left behind after the electrolytic refining of copper metal. The coins made of metal X look new even after several years of use but the coins made of metal Y lose their shine gradually and get blackened soon. When metal X is alloyed with a small amount of metal Y, it becomes hard and hence suitable for making ornaments. What are metals X and Y? Also state the colour of metal X.
Give reasons, why aluminum is used in:
In making ships
Compare the process of calcination and roasting.
What is passive iron?
The following questions relate to the extraction of aluminium by electrolysis.
Explain why it is necessary to renew the anode periodically.
X is an element in the form of a powder. X burns in oxygen and the product is soluble in water. The solution is tested with litmus. Write down only the word which will correctly complete each of the following sentences:
(a) If X is a metal, then the litmus will turn ______.
(b) If X is a non-metal, then the litmus will turn ______.
(c) If X is a reactive metal, then ______ will be evolved, when X reacts with dilute sulphuric acid.
(d) If X is a non -metal, it will form _ oxide, which will form ______ solution with water.
(e) If X is a non -metal, it will not conduct electricity unless it is carbon in the form of ______.
Compare the properties of a typical metal and a non- metal on the basis of the following:
(a) electronic configuration
(b) nature of oxides
(c) oxidizing or reducing action
(d) conductivity of heat and electricity
To protect iron from rusting, it is coated with a thin layer of zinc. Name the process.
Name the following:
A compound which is added to lower the fusion temperature of the electrolytic bath in the extraction of aluminium.
Define calcination.
Iron is _______.
Write the molecular formulae of the following compound.
Fluorspar
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?
- Given below are the steps for extraction of copper from its ore. Write the reaction involved.
- Roasting of copper (I) sulphide
- Reduction of copper (I) oxide with copper (I) sulphide.
- Electrolytic refining
- Draw a neat and well labelled diagram for electrolytic refining of copper
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.
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 a reason why Aluminium is preferably used in thermite reactions.
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.
