Rusting and sacrificial protection of metals

Question 1

rusting/corrosion of iron (hydrated iron(III) oxide) (reddish-brown substance)
equation?

Answer 1

4Fe (s) + 3O2 (g) + 2xH2O (l) –> 2Fe2O3.xH2O (s)

Question 2

keeping the metal away from __ and __ can prevent rusting

Answer 2

air and water

Question 3

rust prevention methods

Answer 3

1. protective layer (paint/grease, plastic, electroplating)
2. sacrificial protection
3. alloys

Question 4

electroplating

Answer 4

• coating iron/steel w layer of another metal by electrolysis
• prevents water and air from coming into contact w surface

galvanising (zinc-plating)

• protective coat of zinc. electroplate iron/steel by dipping it into molten zinc
• zinc more reactive, will corrode instead of iron. iron won’t rust even if zinc layer scratched

Question 5

extraction of metals

Question 6

sacrificial protection

Answer 6

• use more reactive metals (eg magnesium/zinc blocks)

- will corrode instead of iron

Question 7

alloys

Answer 7

e.g.
stainless steel is a rust-resistant alloy of iron and it contains nickel and chromium. when exposed to air and moisture, a very hard coating of chromium(III) oxide, Cr2O3, forms on the surface of stainless steel, protecting it from further corrosion

Question 8

extraction of metals

Answer 8

more reactive –> more stable the compound –> harder to extract metal from ore
see notes lol