1. Direction of Electron Flow During Corrosion
Aim:
To find out the how electrons flow during corrosion.
To find out how to identify electron flow during corrosion.

2. Iron and Magnesium Cell
Pink colour due to the OH- ions
Magnesium
Iron nail
Salt solution with ferroxyl indicator
Iron does not rust in this cell. The electrons flow to the iron. (Mg higher than Fe in the ECS)
Mg  Mg2+ + 2e-
2H2O + O2 4e-  OH-

3. Iron and Copper Cell
Copper
As corrosion takes place, electrons flow away from the iron. (Cu is lower than Fe in the ECS).

4. Fe  Fe2+ + 2e-
2H2O + O2 + 4e-  OH-
The electrons are produced as the iron oxidises. (oxidation)
The pink colour around the copper is due to the corresponding reduction reaction, which results in the formation of OH- ions.

5. Iron and Carbon Cell
In an iron/carbon cell, the blue colour around the iron indicates that the iron is rusting (presence of Fe2+ ions).

6. As corrosion takes place, electrons flow away from iron.
The electrons are produced as the iron oxidises. (oxidation)
The pink colour around the carbon is due to the corresponding reduction reaction, which results in the formation of OH- ions.