iron corrosion—in generaliron corrosion—in general a redox reaction in a makeshift voltaic cell...
TRANSCRIPT
Corrosion
It’s all Redox!
Iron Corrosion—in general
A redox reaction in a makeshift voltaic cell Processes are separate on metal, but often occur
at same areas
Spontaneous process
Electrons move through metal and electrolyte solution is air
Iron Corrosion—now in detail
Cracked/dented iron more susceptible to corrosion Higher energy state---oxidation likely
Oxygen from air oxidizes iron Occurs at “anodic areas” Fe(s) Fe+2 + 2e-
Electrons travel along the iron to “cathodic areas” where reduction occurs Oxygen is reduced O2(g) + 2H2O(l) + 4e- 4OH-
(aq)
**Iron goes through 2 oxidations before “rust” forms.
Corrosion Protection
Multiple ways
2 main ways
1) Galvanized Iron
2) Cathodic Protection
Corrosion Protection—Galvanized Iron
Iron coated with more reactive metal (Zn)
Outer layer of zinc placed around iron Zinc reacts with oxygen in the place of iron Zinc sacrifices itself—goes through corrosion
(Ex. Galvanized iron nails)
Corrosion Protection—Cathodic Protection
Iron/steel connected directly or indirectly to an active metal (Mg, Al, or Zn)
Active metal sacrifices itself in place of the iron/steel “Sacrificial anode”
Iron acts as the cathode and reduction occurs there
Ex. Ships, plumbing, pipes
ENJOY YOUR SPRING BREAK !!!