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प्रश्न
Give preventive methods by giving examples of corrosion?
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उत्तर
Corrosion can be prevented by the following methods:
- Galvanizing: Galvanizing is a process of giving a thin coating of zinc on iron or steel materials to protect them from corrosion. Zinc, being more electropositive than iron, undergoes corrosion first. Thus, it prevents corrosion of iron. However, if zinc layer goes away and the inner iron gets exposed, then the inner iron layer will start to rust.
- Tinning: Tinning is the process of giving a coating of tin over other metals. Cooking vessels, made of copper and brass get a greenish coating due to corrosion. This greenish coating is poisonous. If food is kept in such a vessel, it gets spoiled. Therefore, copper and brass vessels are coated with tin (kalhai) to prevent corrosion.
- Anodizing: The process of coating metals such as aluminium and copper with a thin and strong layer of their oxides by electrolysis is called anodizing process. For this, the copper or aluminium article is used as the anode. As this oxide layer is strong and uniform all over the surface, it is useful for the prevention of the corrosion of the metal.
- Electroplating: Electroplating is the process in which a less reactive metal is coated on a more reactive metal by electrolysis. It protects the object made of reactive metal from corrosion. For example, silver-plated spoons, gold plated ornaments, etc.
- Alloying: The homogenous mixture formed by mixing metal with other metals or nonmetals in a certain proportion is called an alloy Alloying helps to decrease the intensity of corrosion of metals. For example, stainless steel does not get stains with air or water and also does not rust. It is an alloy made from 74% iron, 18% chromium and 8% carbon.
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संबंधित प्रश्न
What is an alloy?
What are alloys?
Explain how painting of an iron gate prevents it from rusting.
What special name is given to the corrosion of iron?
What type of chemical reaction is involved in the corrosion of iron?
Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel.
The chemical reaction involved in the corrosion of iron metal is that of ______.
What is meant by galvanisation? Why is it done?
______ and ______ are necessary for the rusting of iron.
What are the constituents of stainless steel?
Four metals P, Q, R and S are all obtained by the reduction of their oxides with carbon. Metal P is used to form a thin layer over the sheets of metal S to prevent its corrosion. Metal Q is used for electroplating tiffin boxes made of metal S whereas metal R is used in making car batteries. Metals Q and R form an alloy called solder. What are metals P, Q, R and S? How have you arrived at this conclusion?
Bronze is an alloy of ______.
Name the metal which is a constituent of blood pigment?
Explain how the activity series accounts for each of the following:
tendency to corrosion
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
No chemical reaction takes place when granules of a solid, A, are mixed with the powder of another solid, B. However when the mixture is heated, a reaction takes place between its components. One of the products, C, is a metal and settles down in the molten state while the other product, D, floats over it. It was observed that the reaction is highly exothermic.
(i) Based on the given information make an assumption about A and B and write a chemical equation for the chemical reaction indicating the conditions of reaction, physical state of reactants and products and thermal status of reaction.
(ii) Mention any two types of reactions under which above chemical reaction can be classified.
What is done to prevent corrosion of metals?
Choose the correct alternative and rewrite the following:
Iron is _____________________.
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
What is ‘rusting’?
State whether the statement given below is true or false. If false write the correct statement.
Graphite is a lustrous non-metal which conducts electricity.
Observe the following picture and answer the following questions:
- What is rust?
- Write the chemical formula of rust.
- Write the reaction of oxidation of iron at the anode.
- Write the reaction of oxidation of iron at the cathode.
- What is corrosion?
_______ is an alloy made from iron, carbon and chromium.
When one of the metals in an alloy is mercury the alloy is called _______.
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Find the odd one out and give its explanation.
Draw a neat labelled diagram.
Anodizing
Write a molecular formula for rust.
Observe the following diagram and give answers.
- Name this method of prevention of corrosion.
- For prevention of which metal this method is used?
- What is used as anode in this method?
Which among the following alloys contain mercury as one of its constituents?
Identify the correct statement from the following:
Alloys are homogeneous mixtures of a metal with a metal or non-metal. Which among the following alloys contain non-metal as one of its constituents?
Iron pillar near the Qutub Minar in Delhi is famous for the following facts. Which of these facts is responsible for its long stability?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
