Corrosion is an electrochemical phenomenon. The oxygen in moist air reacts as follows:
O 2 (g) + 2H 2 O(l) + 4e – → 4OH – (aq).
Write down the possible reactions for corrosion of zinc occurring at anode, cathode, and overall reaction to form a white layer of zinc hydroxide
Answer:
Anode: Zn (s) → Zn 2+ (aq) + 2 e-
Cathode: O 2 (g) + 2H 2 O(l) + 4e – → 4OH – (aq).
Overall: 2 Zn (s) + O 2 (g) + 2H 2 O(l) → 2 Zn 2+ (aq) + 4OH – (aq)
2 Zn (s) + O 2 (g) + 2H 2 O(l) → 2 Zn(OH) 2 (ppt)
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