Final answer:
The oxidation of iron to rust weakens structures, while the oxidation of aluminum to aluminum oxide forms a protective barrier.
Step-by-step explanation:
The oxidation of iron to rust is a problem for structural engineers because rust weakens structures. Rust is formed when iron reacts with oxygen and water, producing a hydrated form of iron (III) oxide. The rust continually flakes off, exposing a fresh metal surface that is vulnerable to further reaction.
In contrast, the oxidation of aluminum to aluminum oxide is not a significant problem. When aluminum corrodes, it forms a protective barrier of aluminum oxide on its surface. This barrier prevents further reaction with the environment, protecting the underlying aluminum.
In conclusion, the difference in the corrosion behavior of iron and aluminum is due to the nature of the oxide layers formed during the oxidation process.