Question

Discuss the method by which rusting of iron can be prevented

Answer 1

Prevention of Rusting

There are several ways of preventing rusting of iron. Some of these are discussed below:

1. Barrier protection:

In this method, a barrier film is introduced between iron and atmospheric oxygen and moisture. Barrier protection can be achieved by one of the following ways:

By painting the surface coating the surface with a thin film of oil or grease.By electroplating iron with some non-corrosive metal such as nickel, chromium, copper, etc.

2. Sacrificial protection:

In this method, the surface of iron is covered with a layer of more active metal like zinc. This active metal loses electrons (undergoes oxidation) in preference to iron and hence, prevents the rusting of iron.

Zinc metal is generally used for protecting iron and the process is called galvanization. Galvanized iron sheets maintain their shine due to the formation of a thin protective layer of basic zinc carbonate, ZnCO3, Zn (OH) 2 due to the reaction between zinc, oxygen, CO2, and moisture in the air.

Zinc, magnesium and aluminum powder dissolved in paints can also be applied as protective layers. The well-known aluminum paint contains aluminum powder suspended in varnish.

3. Use of anti-rust solutions:

The alkaline phosphate and alkaline chromate solutions act as anti-rust solutions. When iron articles are dipped into a boiling and strongly alkaline solution of sodium phosphate, a protective insoluble film of iron phosphate is formed on them. This film protects the article from rusting

Answer 2

Rusting of iron can be prevented by applying paint on iron articles, greasing and by the method of galvanisation.