Question
Explain how rusting of iron is envisaged as setting up of an electrochemical cell.
Solution
Answer:
At a particular spot of an object made of iron oxidation takes place and that spot behaves as an anode.
At anode:
Electrons released at anode spot moves through the metal and go to another spot on the metal and reduce oxygen in presence of H+ (which is believed to be available from H2CO3formed due to dissolution of carbondioxide from air into water. Hydrogen ion in water may also be available due to dissolution of other acidic oxides from the atmosphere). This spot behaves as a cathode with the reaction.
The ferrous ions are further oxidized by atmospheric oxygen to ferric ions which come out as rust in the form of hydrated ferric oxide (Fe2O3 x H2O).
At a particular spot of an object made of iron oxidation takes place and that spot behaves as an anode.
At anode:
Electrons released at anode spot moves through the metal and go to another spot on the metal and reduce oxygen in presence of H+ (which is believed to be available from H2CO3formed due to dissolution of carbondioxide from air into water. Hydrogen ion in water may also be available due to dissolution of other acidic oxides from the atmosphere). This spot behaves as a cathode with the reaction.
The ferrous ions are further oxidized by atmospheric oxygen to ferric ions which come out as rust in the form of hydrated ferric oxide (Fe2O3 x H2O).
