How does rust work to eat away a metal?

Question

Where does rust come from? How does it begin to form and why only on certain metals?

In: Chemistry

Answer 1

Rust is not the active agent but the outcome of oxidation. Oxygen is the culprit. Oxides are more electrically stable than many pure metals. Aluminum is particularly reactive but the oxide binds to the metal surface protecting the rest of the metal. Iron oxide does not bind so well, so flakes off exposing more of the iron to additional oxygen.