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प्रश्न
What is corrosion?
Give a brief account of corrosion.
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उत्तर
Corrosion is the damage caused to the metal by the chemical reaction of air, water, and acids with the surface of the metal. Generally, reactive metals corrode easily, and non-reactive metals have good resistance to corrosion.
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संबंधित प्रश्न
Give two examples of alloys with their chemical composition.
Write two methods of preventing the rusting of iron.
Why do we apply paint on iron articles?
Which metals do not corrode easily?
Which of the following methods is suitable for preventing an iron frying pan from rusting?
Give reasons:
Platinum, gold and silver are used to make jewellery.
Explain why Iron sheets are coated with zinc during galvanization.
Write a chemical equation to show the process of corrosion of iron.
What special name is given to the corrosion of iron?
What type of chemical reaction is involved in the corrosion of iron?
Name the metal which is used for galvanising iron.
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Fill in the following blanks with suitable words:
Tiffin boxes are electroplated with .............. but car bumpers are electroplated with ............... to protect them from rusting.
Explain why, through aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
What is meant by 'rusting of iron'? With the help of labelled diagrams, describe an activity to find out the conditions under which iron rusts.
What are the constituents of stainless steel?
Explain why, when a copper object remains in damp air for a considerable time, a green coating is formed on its surface. What is this process known as?
Name a common metal which is highly resistant to corrosion.
A common metal which is highly resistant to corrosion is:
(a) iron
(b) copper
(c) aluminium
(d) magnesium
Brass is an alloy of:
(a) Cu and Sn
(b) Cu and Pb
(c) Pb and Sn
(d) Zn and Cu
No chemical reaction takes place when granules of a rusty-brown 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.
(a) What could the solids A and B be?
(b) What are the products C and D most likely to be?
(c) Write the chemical equation for the reaction between A and B leading to the formation of C and D. Mention the physical states of all the reactants and products in this equation and indicate the heat change which takes place.
(d) What is the special name of such a reaction? State one use of such a reaction.
(e) Name any two types of chemical reactions under which the above reaction can be classified.
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 plant pigment?
What is corrosion? What are necessary conditions for corrosion?
Complete the process of iron rusting by filling the blanks. Suggest a way to prohibit the process.
The iron rust is formed due to........................... reaction. Different
regions on iron surface become anode and cathode.
Reaction on anode region :
`F_e(s) → Fe^(2+) (aq) +2e^-`
Reaction on anode region :
`O_2(g) + 4H^+(aq) +............................ → 2H_2 O (l) `
When Fe2+ ions migrate from anode region they react with ................... to form Fe3+ ions.
A reddish coloured hydrated oxide is formed from ............... ions. It is called rust.
`2Fe_(3+) (aq) + 4H_2O(l) → ................. + 6H_+(aq) `
A way to prevent rusting ..................................................................
Answer the following question.
a) What is meant by corrosion?
b) Write names of any two methods of prevention of corrosion.
c) In which method, metal like copper, aluminium are coated with a thin layer of their oxides by means of electrolysis.
d) Explain this method with diagram.
Find the odd man out:
What are the adverse effects of corrosion?
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
Give reason.
Copper and brass utensils should be tinned.
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.
Which of the following method is used to prevent the accumulation of greenish layer on brass due to corrosion?
Corrosion of silver causes a black layer of _______.
When one of the metals in an alloy is mercury the alloy is called _______.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Rusting of iron : Fe2O3 : : corrosion of copper : ______
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 |
Write the name.
An alloy of copper and tin-
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
Explain concept with example/explain with the help of a balanced equation.
Corrosion
State two conditions necessary for rusting of iron.
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?
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?
Gold plated ornaments is the example of ______.
Give scientific reasons.
Silver amalgam is used for filling dental cavities.
In ______ process a layer of molten tin is deposited on metals.
