Understanding Corrosion: The Impact of Coatings on Iron Products

Which coating will contribute to the corrosion of iron products?

A) zinc

B) gold

C) aluminum

D) magnesium

Answer:

Gold (option B) will contribute to the corrosion of iron products because it is less electropositive than iron, and thus, gold acts as a cathode, accelerating iron's oxidation through galvanic corrosion.

The coating that will contribute to the corrosion of iron products is gold (B). This is because gold is a less electropositive metal when compared to iron, meaning it has a higher reduction potential and is less likely to lose electrons and oxidize. When iron is in contact with a more corrosion-resistant metal such as gold, it will corrode more rapidly because the gold acts as a cathode, which increases the rate of reduction of oxygen and subsequently the oxidation of iron.

Galvanic corrosion is a process that occurs when two dissimilar metals are in direct contact, allowing electrons to transfer and accelerating the corrosion of the more anodic (or more easily oxidized) metal. Since gold is less easily oxidized than iron, iron serves as the anode and corrodes. Metals like zinc (A), aluminum (C), and magnesium (D) are more electropositive than iron and would serve as sacrificial anodes to protect the iron from corrosion.