What is the effect on using pure oxygen on rusting?

• A. Rusting is faster when pure oxygen is used.
• B. Rusting is slower when pure oxygen is used.
• C. Rusting is not affected by oxygen concentration.
• D. Rusting stops when pure oxygen is used.

Answer: (A)

Rusting is an oxidation reaction on iron that requires oxygen and water. The rate of rusting depends on how much oxygen is available to react with the iron. Using pure oxygen provides a much higher concentration of the oxidizing agent, so more oxygen molecules reach the iron surface and participate in the redox reactions every second. With more collisions and electron-transfer events at the surface, rust forms faster than in normal air. Therefore, rusting speeds up with pure oxygen rather than slowing down or stopping.