Corrosion - an electrochemical reaction
Electrochemical or redox reactions are tremendously damaging to modern society e.g. - rusting of cars, etc:
anode: Fe - ? Fe2+ + 2 e-
net: 2 Fe(s) + O2 (g) + 2 H2O (l) ? 2 Fe(OH)2 (s)
Mechanisms for minimizing corrosion
- sacrificial anodes (cathodic protection) (e.g. Mg)
- coatings - e.g. galvanized steel
- - Zn layer forms (Zn(OH)2.xZnCO3)
- this is INERT (like Al2O3); if breaks, Zn is sacrificial
cathode: O2 + 2 H2O + 4 e- ? 4 OH-