Question

71. Write a short note on rusting. What are the causes and effects of it? Explain different methods adopted to prevent rusting.

Answer 1

Part 1: Rusting:

Rusting is the process in which Iron $\left(\mathrm{Fe}\right)$ comes in contact with oxygen and moisture present in the air, and gets converted into a reddish-brown hydrated Iron oxide $({\mathrm{Fe}}_2{\mathrm{O}}_3.{\mathrm{xH}}_2\mathrm{O})$ known as rust.

Part 2: Causes and effects of rusting:

• Rust is formed after the iron particles have been exposed to oxygen and moisture for a long period of time.

The effects of rusting are:

1. Moisture: Greater the amount of moisture in the environment, the more will be the rusting.
2. Impurity: Iron-containing a mixture of metals tends to rust faster as compared to pure iron.
3. Acid: If the pH of the environment surrounding the metal is high, then corrosion will be at a slower rate.

Part 3: Methods to prevent rusting:

• Galvanization: It is the process of coating iron metal with a layer of Zinc$\left(\mathrm{Zn}\right)$. This protects the iron from rusting.
• Coating with enamel paint: Applying enamel paint to the objects which are made of iron protects the iron from rusting.
• Applying oil and grease: The machine or engine parts are coated with a layer of oil and grease to prevent not only rusting but also lubricating them.
• Electroplating: In this process, iron is coated with metals like chromium $\left(\mathrm{Cr}\right)$ or nickel $\left(\mathrm{Ni}\right)$ which helps in preventing the rusting of iron.