1. Unit 8: Electrochemistry Applications
Lesson 5:
Corrosion of Metals

2. What Makes Metals Corrode?
Water and oxygen!
10 min
(Oxygen-rich)
(Fe2O3·xH2O)
(Oxygen-poor)

3. Brain Break!
Spot It!

4. How to Prevent Corrosion
1. Apply a protective layer such as paint or plastic. If oxygen and water can’t contact the metal, it won’t corrode.

5. Coat (“plate”) the metal with a different metal that is corrosion-resistant.
E.g. Tin quickly oxidizes at its surface to produce a thin tin oxide layer that adheres strongly to the pure tin underneath, preventing further corrosion.
Tin cans are actually tin-plated steel!

6. 3. Use cathodic protection
3. Use cathodic protection. This is the process of protecting a metal from unwanted oxidation by attaching it to a different metal with a stronger tendency to oxidize. The “sacrificed” metal will act as an anode, so that the metal to be protected will act as a cathode and stay in its reduced form!

7. Practice:
Pg. 234 #57-59
Pg. 236 #60-63
20 min