Question

Can the rusting of iron nails occur in distilled water? Justify your answer

Answer 1

Hint: Rusting of iron is known as Corrosion. Corrosion is happening in metallic objects; it slowly coats the surface with oxides or other salts of the metal. Corrosion metal is oxidized by loss of electrons to oxygen and formation of oxides.

Complete step by step answer:
Corrosion metal surface is getting coated with oxides or other salt of the metal. Rusting of iron, tarnishing of silver are some examples for Corrosion.
In Corrosion, metal is oxidized by loss of electrons and to Oxygen and formation of oxides. Rusting of iron usually occurs in the presence of air and water.
Rusting of iron is a Redox reaction. Oxidation takes place at a particular spot in the metal.
              Anode: \[2Fe\left( s \right)\;\;\xrightarrow{{}}\;\;\;2F{e^{2 + }} + {\text{ }}4{e^ - }\]
The released electrons move through the metal and reach another spot and reduce oxygen in presence of H+ ion. This spot acts as the cathode.
Cathode: \[2F{e^{2 + }}\left( {aq} \right) + 2F{e^{2 + }}\left( {aq} \right) + 2H2O\left( l \right) + \dfrac{1}{2}\;O2\left( g \right)\; \to F{e_2}{O_3}\left( s \right) + 4H + \]
The Overall reaction is:
 \[2Fe\left( s \right) + O2(g) \to \;2F{e^{2 + }}\left( {aq} \right) + 2{H_2}O\left( l \right)\]
The ferrous ions are oxidized by atmospheric oxygen to ferric ions. Then it will come out as rust in the form of hydrated ferric oxide.
In distilled water Rusting of iron can occur. Because distilled water contains dissolved oxygen. Iron will react with Oxygen in presence of water and it forms a layer of Iron Oxide.
Atmospheric oxidation: \[2F{e^{2 + }}\left( {aq} \right) + 2F{e^{2 + }}\left( {aq} \right) + 2H2O\left( l \right) + \dfrac{1}{2}\;O2\left( g \right)\; \to F{e_2}{O_3}\left( s \right) + 4H + \]

Due to the presence of dissolved oxygen in water Rusting of Iron will happen in distilled water.

Note: Rusting causes enormous damage to buildings, bridges, ships etc. We can prevent corrosion by preventing the surface of the metal from coming in contact with atmospheric oxygen. Covering the surface with paint can be done to avoid corrosion. Another method is to cover the surface with inert metals.