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प्रश्न
What is anodising? Give its applications.
What is meant by 'anodising'? Why is it done?
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उत्तर १
Anodising is an electrolytic passivation process used to increase the thickness of the natural oxide layer on the surface of metal parts. The process is called anodising because the part to be treated forms the anode electrode of an electrical circuit.
It is very useful in preventing the metal from corrosion. It is also useful in architectural finishing.
उत्तर २
Anodising is a method that involves the formation of tough layer of aluminium oxide on aluminium substances by making it anode in the electrolysis of sulphuric acid. Generally, the formation of aluminium oxide layer on aluminium protects it from corroding further. However, if this oxide layer on aluminium is made thicker (by anodising), it will become a strong coating and will prevent corrosion to the maximum.
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संबंधित प्रश्न
Tinning : Tin : : Galvanizing : _________
Explain why rusting of iron objects is faster in coastal areas than in deserts.
Write a chemical equation to show the process of 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.
Explain why, iron sheets are coated with zinc.
Why is an iron grill painted frequently?
Explain why, through aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
Give the constituents and one use of brass.
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
What are the special properties of stainless steel?
In stainless steel alloy, iron metal is mixed with:
(a) Cu and Cr
(b) Cr and Ni
(c) Cr and Sn
(d) Cu and Ni
A metal X which is resistant to corrosion is produced by the electrolysis of its molten oxide whereas another metal Y which is also resistant to corrosion is produced by the reduction of its oxide with carbon. Metal X can be used in powder form in thermite welding whereas metal Y is used in making cathodes of ordinary dry cells.
(a) Name the metals X and Y.
(b) Which of the two metals is more reactive : X or Y?
(c) Name one ore or metal X. Also write its chemical formula.
(d) Name one ore or metal Y. Also write its chemical formula.
(e) Name one alloy of metal X and one alloy of metal Y.
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?
State under what conditions corrosion is faster ?
Compare roasting and calcination.
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
Write scientific reasons.
Lemon or tamarind is used for cleaning copper vessels turned greenish.
Identify the process shown in the diagram and explain it in short
What are the adverse effects of corrosion?
Write three methods of preventing rusting of iron.
Give reason.
A wooden article should be polished.
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?
Find the odd one out and give its explanation.
Find the odd one out and give its explanation.
Match the columns.
| Group A | Group B |
| 1) Electroplating | a) Pressure cooker |
| 2) Anodising | b) Silver plated spoons |
| c) Coating of tin on copper | |
| d) Coating of Zinc on iron |
Explain concept with example/explain with the help of a balanced equation.
Corrosion
Draw a neat labelled diagram.
Anodizing
Observe the following figure and write the answer of the question.
- Which process is shown in the figure?
- Explain the chemical reaction shown in the figure.
- Write the reactions on anode and cathode.
Amalgam is an alloy of ____________.
The diagram shows the reaction between metal and dil. acid.
What is the reason for different behaviour of Mg in test tube B?
Generally, when metals are treated with mineral acids, hydrogen gas is liberated but when metals (except Mn and Mg), treated with HNO3, hydrogen is not liberated, why?
Galvanisation is a process used to prevent the rusting of which of the following?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
Explain the following:
Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.
Gold plated ornaments is the example of ______.
