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प्रश्न
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.
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उत्तर
Iron objects, kept in moist air for a long period of time, react with moist air to form a reddish brown crumbling substance called rust (hydrated iron (III) oxide, Fe2O3. X H2O, where X is the number of moles of water that differs). This corrosion of iron metal by reacting with moist air is called the rusting of iron.
Conditions essential for the rusting of iron:
1. Presence of air (oxygen)
2. Presence of water (moisture)
Let us do an activity to prove that moist air is necessary for the rusting of iron.
Experiment: Take three test tubes and place a dirt-free iron nail in each of these test tubes (refer to the figure below). In the first test tube, anhydrous calcium chloride is added and the test tube is closed. In the second test tube, distilled water and a layer of oil is added and the test tube is closed with a cork. In the third test tube, tap water is added. The nail is dipped into water in such a way that a part of it is exposed to the damp air present inside the test tube.
Observation:
(i) The nails in the first and the second test tube do not rust.
ii) The nail present in the third test tube rusts.
Conclusion:
Hence, we can conclude that both air and water are necessary for the rusting of iron.
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संबंधित प्रश्न
What is anodising? Give its applications.
Name any three objects (or structures) which are gradually damaged by the corrosion of iron and steel.
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 constituents of stainless steel?
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.
Name the metal which is a constituent of plant pigment?
What is corrosion? What are necessary conditions for corrosion?
Corrosion can be an advantage in some case.Explain ?
Compare roasting and calcination.
Explain with reason:
Roasting is carried out on sulphide ores and not on carbonate ores.
Identify the process shown in the diagram and explain it in short
Find the odd man out:
Answer the following question:
What is corrosion? Do gold ornaments corrode? Justify.
Write three methods of preventing rusting of iron.
Pressure cooker : Anodizing : : Silver plated spoons : _______
Rusting of iron : Fe2O3 : : corrosion of copper : ______
Find the odd one out and give its explanation.
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?
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?
Galvanisation is a process used to prevent the rusting of which of the following?
