C6.1.11 Rust

Question 1

Rusting

Answer 1

Hydrated iron (lll) oxide

Question 2

Colour

Answer 2

Orange-brown

Question 3

Copper 2+

Answer 3

Blue

Question 4

Iron 2+

Answer 4

Green

Question 5

Iron 3+

Answer 5

Orange-brown

Question 6

Anhydrous

Answer 6

W/o water

Question 7

Need both

Answer 7

Water and air to rust

Question 8

Equation

Answer 8

Iron + oxygen + water —> hydrated iron (lll) oxide

Question 9

Experiment to show…

Answer 9

1) to show water alone isn’t enough put iron nail in a boiling tube with just water + nail won’t rust (boil water)
2) show oxygen alone isn’t enough put iron nail in boiling tube with just air and nail won’t rust
(Calcium chloride can be used to absorb any water from air)
3) if you put iron nail in boiling tube with air and water = will rust

Question 10

Prevent rusting

Answer 10

Painting + coating with plastic - ideal for big + small structures can also be decorative
Electroplating - uses electrolysis to reduce metal ions onto an iron electrode can be used to coat the iron with a layer of a different metal that won’t be corroded away
Oiling/greasing used when moving parts are involved like on a bike chain

Question 11

Sacrificial method

Answer 11

Involves placing a more reactive metal e.g. zinc/magnesium with the iron. Water + oxygen then react with the sacrificial metal instead of the iron