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प्रश्न
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?
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उत्तर
- Rust is a reddish-brown coloured hydrated ferric oxide layer deposited on the surface of iron objects that are exposed to moist air.
- Chemical formula of rust is Fe2O3.xH2O.
- Anode region: \[\ce{Fe_{(s)} -> Fe^{2+}_{ (aq)} + 2e^-}\]
- Cathode region: \[\ce{Fe^{2+}_{ (aq)} -> Fe^{3+}_{ (aq)} + e^-}\]
- Metals get attacked by substances around it such as moisture, acids, etc. Metal is said to ‘corrode’ due to this attack and the process is called corrosion.
APPEARS IN
संबंधित प्रश्न
Write two methods of preventing the rusting of iron.
Explain the terms Corrosion
Answer the following question.
What are alloys?
Explain why Iron sheets are coated with zinc during galvanization.
Choose the correct answer from the options given below:
Heating an ore in a limited supply of air or in the absence of air at a temperature just below its melting point is known as
A. Smelting
B. Ore-dressing
C. Calcination
D. Bessemerisation
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:
(a) oxidation as well as displacement
(b) reduction as well as combination
(c) oxidation as well as combination
(d) reduction as well as displacement
Name the metal which is used for galvanising iron.
State two conditions for the rusting of iron.
Fill in the following blanks with suitable words:
Tiffin boxes are electroplated with .............. but car bumpers are electroplated with ............... to protect them from rusting.
Fill in the following blanks with suitable words:
............ and .............. are necessary for the rusting of iron.
Explain why, through aluminium is more reactive than iron, yet there is less corrosion of aluminium when both are exposed to air.
Name two metals which resist corrosion due to the formation of a thin, hard and impervious layer of oxide on their surface.
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?
A common metal which is highly resistant to corrosion is:
(a) iron
(b) copper
(c) aluminium
(d) magnesium
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
Compare roasting and calcination.
Observe the following picture a write down the chemical reaction with the explanation.
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.
Give a reason why rust turns moist red litmus blue.
To prevent corrosion of iron and steel _______ method is used.
_______ forms a green colour in the water.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Write the name.
Method used to prevent corrosion of copper.
Write scientific reason.
On exposure to air, silver articles turn blackish after some time.
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?
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.
The process of coating the surface of the metal with a thin layer of zinc is called ______
Give the equation for the formation of rust.
Marble’s popularity began in ancient Rome and Greece, where white and off-white marble were used to construct a variety of structures, from hand-held sculptures to massive pillars and buildings.
The substance not likely to contain CaCO3 is:
Alloys are homogeneous mixtures of a metal with a metal or nonmetal. 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?
State whether the following statement is true or false:
Ships suffer a lot of damage though they are painted.
