the chemistry of corrosion of iron is essentially in electrochemical phenomenon explain the reaction occuring during the corrosion of iron in the atmosphere
Answers
The process of corrosion is a redox reaction that involves simultaneous oxidation and reduction reactions. It can therefore be referred to as an electrochemical reaction.
In the process of corrosion, due to the presence of air and moisture, oxidation takes place at a particular spot of an object made of iron. That spot behaves as the anode. The reaction at the anode can be written as follows.
Anodic reaction:
Electrons released at the anodic spot move through the metallic object and go to another spot of object. There, in the presence of H+ ions, the electrons reduce molecular oxygen. This spot behaves as the cathode. There H+ ions come either from H2CO3 , which are formed due to the dissolution of carbon dioxide from air into water or from the dissolution of other acidic oxides from the atmosphere in water.
The reaction corresponding at the cathode is written as follows.
Cathodic reaction:
Thus, the overall reaction is:
Also, ferrous ions are further oxidized by atmosphere oxygen to ferric ions. These ferric ions combine with moisture, present in the surroundings, to form hydrated ferric oxide (Fe2O3, xH2O) i.e., rust.