Iron + Water + Oxygen → Hydrated Iron(III) Oxide
4Fe (s) + 3O2 (g) + xH2O (l) → 2Fe2O3.xH2O (s)
Diagram showing the requirements of oxygen and water for rust to occur: only the nail on the left rusts
Zn → Zn2+ + 2e–
2H+ + 2e– → H2
Corrosion and rusting are not the same process. Corrosion is the general term used to describe the degradation of metal surfaces whereas rusting is the specific type of corrosion that happens to iron.