Corrosion Flashcards
What is corrosion ?
The destruction of materials by chemical reactions with substances in the environment
What is rusting ?
The corrosion of iron and alloys of iron
Only Iron can Rust !
What copper rust ?
No, only Iron and Iron alloys can rust (1)
Copper will corrode (1)
What does rust require ?
Oxygen and water
What is the formula of rust ?
Hydrated iron(III) Oxide or Fe2O3
How would we carry out an experiment on the conditions required for rust ?
- Have three separate test tubes one
- one with an iron nail fully submerged in distilled water and it’s open to air (water+air)
- another with an iorn nail fully submerged in boiled water covered with oil (water but no air)
- third test tube is anhydrous calcium chloride powder and a nail with no water aswell as a rubber bung on top (air but no water)
Why do we boil the water in the second test tube ?
Removes any dissolved air which could jeopardize the validity of the experiment
Why is the second test tube covered in a layer of oil ?
Prevents any air in the test tube from dissolving in the water
In the third test tube why is there calcium chloride ?
Why is there a rubber bung on the top?
Removes any water from the test tube
Prevents any moist air from entering
What are the observations you would expect to see in the test tubes ?
Test tube 1: the iron nail is covered in rust
Test tube 2+3: the iron nail has not rusted
What is the conclusion from the experiment ?
Rust requires both air and water
What are the three methods of corrosion prevention via barrier ?
Grease
Paint
Electroplating
What would painting, oiling or greasing a surface do to stop corrosion ?
Prevents oxygen and water reaching the metal
What is galvanizing ?
An added layer of Zinc which acts as a barrier against air and water
Preventing the iron from corroding
If the zinc gets scratched on a galvanized surface will if still work ? If so why
Yes but zinc is more reactive than iron meaning Zinc will corrode instead of the iron
