Boxi Learn › Chemistry › Stage 3 · Structure and Evidence
What does a nail need to rust?
CHEM-1 Atoms are rearranged, never lostX-1 Guess, then checkX-2 Evidence outweighs opinion
What many people think
Water alone makes iron rust, so a nail fully under water always rusts.
The idea
Iron rusts only when water and oxygen are both present; take away either one and the nail stays almost bright.
Explain it
Tube B used boiled water and an oil layer. What would go wrong with only the boiling, or only the oil?
Try at home
With an adult: put three plain steel nails (not shiny galvanised ones) in three jars. One in tap water; one in water you have just boiled and cooled, with a layer of cooking oil on top; one dry, with a silica-gel packet and a lid. Look every day for a week.