What is the purpose of magnesium metal when an iron buried underground?

Question

What is the purpose of magnesium metal when an iron buried underground?

Answer 1

Magnesium acts as a sacrificial anode.



Oxygen in the atmosphere reacts with iron to oxidize it in what is called a redox reaction (oxidation/reduction). The redox reaction is defined by the exchange of electrons--uncharged iron will lose two electrons to an oxygen molecule, creating iron oxide. Water quicken rusting by serving as a catalyst. Dissolved oxygen in the water reacts, and as the water dries, the oxygen becomes increasingly concentrated.



Engineers will prevent wide-spread rusting by creating what is called a "sacrificial anode." You might know the names anode and cathode from the ends of a battery. Batteries function by employing two seperate redox reactions, where one end corrodes to release electrons, which travel to the other end and react with metal cations in solution, turning them to a solid metal. The corrosion of iron is prevented by creating a sacrificial anode out of something even more reactive than the iron (usually magnesium). The corrosion of the magnesium releases excess electrons in the iron, which delays corrosion of the iron--oxygen can grab the free electrons created by the corrosion of magnesium without needing to corrode the iron.

Answer 2

Decoy answer, vote for the one above

:)