Rusting

• What is needed in order for iron to rust?

  Oxygen and water
• Anhydrous - no water
• Experiment to investigate what causes rusting: Iron nail placed in water with no bung, iron nail placed in anhydrous calcium chloride with a bung and iron nail was placed in water and vegetable oil with a bung

  1. Why was vegetable oil used?
  2. Why was boiled water used ?
  3. Why was anhydrous calcium used?


  1)Vegetable oil creates a barrier between oxygen and water

  2)Water is boiled to remove any air that may be dissolved in it

  3)It absorbs the water vapour in the test tube
• Iron nail and water- covered in brown rust. Rust has been collected up at the bottom of the tube

  Iron nail, boiled water and vegetable oil- No observable change; rust was already there

  Iron nail and calcium chloride- Nail is intact(no rust)
• What does galvanising mean?

  Painted with a protective layer of zinc
• Conditions that speed up rusting:

  • Salt- This is why cars near the coast(where there is spray from the sea) often rust more than other cars.
  • Acid- Burning fossil fuels can cause acid rain and this can speed up rusting.
  • Heat- this is why exhaust pipes on cars rust faster than the rest of the car.
• Preventing rusting: Rusts can be prevented by sacrificial protection and by any method that prevents air and water reaching the iron surface such as:

  • Painting eg. cars, ships, bridges
  • Coating with oil eg. bicycle chains
  • Plating with another metal such as tin(eg.canned food) or zinc(galvanised iron) This also protects the iron by sacrificial protection
  • Mixing steel with chromium and nickel to make stainless steel which doesn't rust (used for cutlery). However, this makes it more expensive