Question

Write three methods of preventing rusting of iron.

Answer 1

Hint: Rusting is one of the ways of corrosion in metals and corrosion leads to gradual degradation of metals. Notice that, many of the iron items in your surroundings are either painted or coated with another metal which is higher in position than iron in the reactivity series.

Complete step by step answer:
Rusting of iron is an example of corrosion. Corrosion is a slow process and in this, a metal is oxidised by loss of electrons to oxygen and formation of oxides. Corrosion of iron (commonly known as rusting) occurs in the presence of water and air. Corrosion of metals is essentially an electrochemical phenomenon.
 Rusting of iron causes enormous damage to buildings, bridges, ships, and to all objects made of iron. Thus, prevention of rusting of iron is of prime importance. It not only saves the money but also helps in preventing accidents such as bridge collapse or failure of a key component due to corrosion.
One of the simplest methods of preventing rusting of iron is to prevent the surface of the iron from coming in contact with the atmosphere. This can be done by the following various methods:

1.) Coatings: Many different types of coatings can be applied to the surface of the exposed metal (i.e. iron in case of rusting) in order to prevent corrosion. Common examples of coatings that prevent corrosion include paints, wax tapes, and varnish.
2.) Galvanization: It is the process of applying a protective layer of zinc on the iron metal. Zinc is more reactive than iron because it is at a higher position than iron in the reactivity series (recall the reactivity series of metals). It is a very common method of preventing the rusting of iron.
3.) Electrochemical method (also called cathodic protection): In this process, we make iron a galvanic cell cathode. Iron is connected with an electrode of more reactive metal such as Mg or Zn. The more reactive metals will have a greater tendency to get oxidised and thus they will behave as anode and consequently, iron will behave as cathode. Thus, in this way, we prevent the oxidation of iron.

Note: Iron develops rust when reacts with oxygen present in the air. Rust is basically an iron oxide having chemical formula as $F{e_2}{O_3}.3{H_2}O$ (hydrated iron (III) oxide).
All the chemical reactions of rusting of iron are dependent on the presence of water and oxygen. Thus, the rusting of iron can be controlled by restricting the amount of oxygen and water surrounding the metal. Covering with chemicals like bisphenol also prevents the rusting of iron.