(a) Aluminum metal is used as a sacrificial anode to protect offshore pipelines in salt water from corrosion. Why is the aluminum referred to as a "sacrificial anode"? (b) Looking in Appendix E, suggest what metal the pipelines could be made from in order for aluminum to be successful as a sacrificial anode.

Sacrificial anodes are metals that are used to prevent a more valuable metal, like the material of a pipeline, from corroding. They are referred to as "sacrificial" because they are more likely to corrode than the protected metal. When the sacrificial anode corrodes, it forms a continuous flow of metal ions, which helps to prevent metal particles from breaking away and corroding the protected pipeline. In this case, aluminum is used as the sacrificial anode to protect offshore pipelines in salt water.

In order for aluminum to successfully protect the pipeline as a sacrificial anode, the pipeline needs to be made from a metal that is less likely to corrode than aluminum. In Appendix E, we can find the standard reduction potential values for various metals. Aluminum has a standard reduction potential value of -1.66 volts. A metal with a higher reduction potential value will be less likely to corrode. Some possible metals for the pipeline could be: 1. Copper (\(Cu\)) with a standard reduction potential of +0.34 volts 2. Iron (\(Fe\)) with a standard reduction potential of -0.44 volts 3. Nickel (\(Ni\)) with a standard reduction potential of -0.25 volts These metals have higher reduction potential values than aluminum, meaning that they are less likely to corrode when the aluminum sacrificial anode is in place.