Question

You wish to prevent the iron in your car from rusting by installing a sacrificial anode. (Assume rust contains Fe 2+ ion.) If you had blocks of copper, palladium, or zinc, which metal would make the best sacrificial anonde? Briefly defend your answer.

Answer 1

We should prefer using the Zinc block due to its high reactivity as compared to palladium or copper.
Explanation:

A sacrificial anode is a block of metal that is more reactive than iron. The more reactive a metal is the easier it gives away electrons. This reactive block of metal acts as a source of electrons for the iron. When oxygen takes electrons from the iron during the process of rusting, iron atoms simply take electrons from the reactive metal.

If we wrap zinc around an iron nail the nail is protected from rusting. Notice that the iron does not have to be completely covered in order to be fully protected. This is a real advantage to using a sacrificial anode. Corrosion is occurring at a high rate but it is not iron but rather zinc that is rusting. Simply put, the zinc is sacrificing itself to protect the iron hence the name sacrificial anode.

And, the more reactive the metal, the faster the overall reaction, and better the rust prevention.

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