What is the effect on rusting when pure oxygen is used?

• A. Rusting is faster when pure oxygen is used
• B. Rusting is slower when pure oxygen is used
• C. No effect on rusting
• D. Rusting stops completely

Answer: (A)

Rusting is an electrochemical process that needs oxygen and water to proceed. The rate at which it happens depends on how much oxygen is available to react with the iron. When you use pure oxygen, there are many more oxygen molecules reaching the iron surface than there are in air, so more iron atoms can be oxidized each second. The result is a faster formation of rust, assuming moisture is present to allow the necessary ion movement. In a completely dry environment, rusting would be very slow or minimal because water is needed for the corrosion process, but with pure oxygen in a moist setting, rusting speeds up.