Rusting of iron — lesson. Science State Board, Class 7.

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எங்கள் ஆசிரியர்களுடன் 1-ஆன்-1 ஆலோசனை நேரத்தைப் பெறுங்கள். டாப்பர் ஆவதற்கு நாங்கள் பயிற்சி அளிப்போம்

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We come across many iron articles around us. Iron is used in making bridges, ships, cars, truck bodies, grills in windows, etc.

Rusted iron chains

Iron turns into rust when exposed to air and moisture in the atmosphere.

Rusting is an example of a chemical change where the process cannot be reversed, and a new substance is formed. This is also called as a chemical reaction. Rusting becomes faster when there is humidity and high salt content in water.

\begin{array}{l} Iron + Oxygen + Water \to Iron oxide (rust) \\ Fe + O_{2} + H_{2} O \to {Fe}_{2} O_{3} \end{array}

Prevention:

1. Frequent coating of paint or grease on iron articles slower the process of rusting.

Coating iron ship with paint

2. Galvanisation (depositing a layer of zinc on iron).

Galvanised iron sheets

3. Alloy (mixing iron with other metals).

Gold chain mixed with other metals

The iron galvanized pipes are used in our homes to carry water to prevent rusting. Ships suffer a lot of damage from rusting so to prevent its damage, stainless steel is made by mixing iron with carbon and metals like chromium, nickel and manganese.

Rusted iron ships

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2. Rusting of iron

Theory: