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प्रश्न
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.
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उत्तर
- The process shown in the figure is rusting (corrosion) of iron.
- The process involves electrochemical reaction. Different regions on the surface of iron become anode and cathode. In the anode region, Fe is oxidized to Fe2+. The electron released in the anode region flow through the metal surface to the cathode region where they reduce oxygen.
In the cathode region, O2 is reduced to form water. When Fe2+ ions migrate from the anode region, they react with water (or OH− ions) and further get oxidized to Fe3+ ions. Fe3+ ions form an insoluble hydrated oxide (Fe2O3.H2O), which is deposited as reddish-brown layer on the surface. It is called rust.
\[\ce{2F^3+_{(aq)} + 4H2O_{(l)} -> \underset{\text{Rust}}{Fe2O3.H2O_{(s)}} + 6H+_{(aq)}}\] - Anode region: \[\ce{Fe_{(s)} -> Fe^2+_{(aq)} + 2e^-}\]
Cathode region: \[\ce{O_{2(g)} + 4H^+_{(aq)} + 4e^- -> 2H2O_{(l)}}\]
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संबंधित प्रश्न
Write two methods of preventing the rusting of iron.
Explain the terms Corrosion
Which metals do not corrode easily?
Give reasons:
Platinum, gold and silver are used to make jewellery.
Two methods by which rusting of iron can be prevented are ______ and ______.
Explain how painting of an iron gate prevents it from rusting.
What is anodising? Give its applications.
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
In one method of rust prevention, the iron is not coated with anything. Which is this method?
Name any two metals which do not corrode easily.
Give the constituents and one use of brass.
Name an alloy of copper. State its chemical composition and any one use.
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
If copper is kept exposed to damp air for a considerable time, it gets a green coating on its surface. This is due to the formation of:
(a) hydrated copper sulphate
(b) copper oxide
(c) basic copper carbonate
(d) copper nitrate
Mention two uses of the following metals and non-metals
Iron
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 ..................................................................
What is done to prevent corrosion of metals?
Give reason for the following:
A suspension of rust is basic in nature.
When one of the metals in an alloy is mercury the alloy is called _______.
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 the name.
Method used to prevent corrosion of copper.
Write scientific reason.
Anodization method is useful for prevention of the corrosion of the aluminium.
Draw a neat labelled diagram.
Anodizing
Write a molecular formula for rust.
State two conditions necessary for rusting of iron.
Amalgam is an alloy of ____________.
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?
A man painted his main gate made up of iron, to
- prevent it from rusting.
- protect it from sun.
- make it look beautiful.
- make it dust free.
Which of the above statement(s) is/are correct?
Explain the following:
Bubbles are produced when acetic acid is added to a solution of sodium hydrogencarbonate.
Gold plated ornaments is the example of ______.
| A process of forming a thick oxide of aluminium when aluminium is exposed to air. This coat makes it resistant to corrosion. Resistance can be improved by making a layer of oxide thinker. In this technique, the aluminium article is the anode, and the electrolyte is sulphuric acid. The anode reaction results in the formation of a black-coloured film of aluminium oxide on the anode. By putting appropriate dyes in the electrolytic solution, both coloured surface with the decorative finish is achieved. Kitchen articles like anodised such as pressure cookers, pans and frames of sliding windows are applications of this technique. |
- Name the anode and electrolyte used in this technique.
- How can we make aluminium articles made resistant to corrosion?
- Name the technique used to coat the aluminium articles.
Describe two changes that are harmful. Explain why you consider them harmful. How can you prevent them?
