Corrosion of metals
Answers are for parents and teachers.
1
Write the anode and cathode reactions of the rusting of iron.
Anode: Fe – 2e⁻ → Fe²⁺; cathode: O₂ + 2H₂O + 4e⁻ → 4OH⁻.
2
Zinc plates are fixed to ships' hulls. What is the reason?
Zinc is more active — it becomes the anode and is consumed while the steel hull is saved as the cathode (protector protection).
3
How many moles of O₂ are needed to rust 112 g of iron? (4Fe + 3O₂ + 6H₂O → 4Fe(OH)₃; A(Fe) = 56)
1.5
4
Name three simple ways to protect iron objects from rust at home.
Keep them dry, paint or oil them, or use galvanised or stainless materials.
5
Why does stainless steel not rust?
Chromium (and nickel) are added and a dense oxide film forms on its surface.