Iron

Question 1

what is iron used for?

Answer 1

• building construction
• car manufacture
• garden furniture

Question 2

how does iron rust?

Answer 2

when iron is in contact with both oxygen and water

Question 3

what type of reaction takes place when iron corrodes?

Answer 3

• an oxidation reaction - iron gains oxygen to form iron (III) oxide
• water then becomes loosely bonded to the iron (III) oxide and the result is hydrated iron(III) oxide

Question 4

what is the word equation for iron rusting?

Answer 4

iron + oxygen + water -> hydrated iron(III) oxide

Question 5

what are properties of iron?

Answer 5

• grey
• shiny
• malleable

Question 6

what are properties of rust?

Answer 6

• brown
• dull
• brittle

Question 7

barrier methods to prevent rust

Answer 7

1. coating the iron in paint or plastic for larger, more stationary objects, such as buckets
2. coating the iron in grease or plastic for moving parts, such as bike chains
   - this prevents the iron from coming into contact with oxygen or water
   NOTE: this only works as long as the coating is intact, as soon as it breaks, rusting happens

Question 8

sacrificial protection to prevent rust

Answer 8

attach a block of a more reactive metal to the iron, such as magnesium - this works by displacing the iron from the rust as soon as it forms
NOTE: the negative to this method is that the block of the more reactive metal has to be replaced often

Question 9

galvanising to prevent rust

Answer 9

• a coating of zinc can be sprayed onto the object
• this prevents the oxygen and water from coming into contact with the iron
• but even if a crack appears, zinc is more reactive so it acts as sacrificial protection as well