Chemistry Class 12
Solutions to CBSE Sample Paper - Chemistry Class 12

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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Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 14 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.