Underground steel (iron) pipelines are crucial for transporting natural gas but are highly susceptible to corrosion.
Identify the two environmental substances that must come into contact with the steel pipeline for corrosion (rusting) to occur.
Give the systematic chemical name of the principal red-brown compound that constitutes rust.
Steel can be protected by different surface barrier methods depending on the application. Complete the table below by matching each prevention method with the most appropriate steel component from the list. You may use each component only once.
List of components:
| Method | Example of use |
|---|---|
| Plastic (polymeric) coating | |
| Galvanising / Zinc plating | |
| Lubricating grease |
Instead of coating the entire underground pipeline, engineers regularly attach blocks of magnesium to the steel pipe at intervals. Explain, in terms of electron transfer and reactivity, how these magnesium blocks protect the underground steel pipeline from corrosion, even if the pipeline is scratched.
