Corrosion and its prevention
Electrochemistry · Chemistry
Study notes
Why does a zinc-coated (galvanized) nail resist rust even when scratched? Step 1: Zn (E° = −0.76) is more reactive than Fe (E° = −0.44). Step 2: Exposed at scratch: Zn becomes the anode, corrodes preferentially. Step 3: Fe stays cathode — protected while any Zn remains. Step 4: Contrast paint: a scratch exposes Fe → rust creeps under paint. Galvanization protects electrochemically, not just as a cover.