Module C2 - Rocks And Metals - Building Cars

Iron And Steel Corrode Much More Than Alminium, Reclcling Cars Is Important

Car Bodies: Aluminium Or Steel

You Need Various Materials To Build Different Bits Of A Car

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Iron And Steel Corrode Much More Than Aluminium P1

Iron corrodes easily.  In other words it rusts.  Rusting only happens when the iron's in contact with both oxygen (from the air) and water.  

The chemical only happens when the iron corrodes is an oxidation reaction.  The iron gains oxygen to form iron(111) oxide.  Water then becaomes loosley bonded to the iron(111) oxide and the result is that hydrated iron(111) oxide - which we call rust.

Learn the word equation:

iron+oxygen+water---> hydrated iron(111) oxide

Unfortunately, rust is a soft crumbly solid that soon flakes off to leave more iron available to rust again.  

And if the water's salty or acidic, rusting will take place a lot quicker.  Cars in coastal places rust a lot because they get covered in salty sea-spray.  Cars in dry deserty places hardly rust at all. 

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Iron And Steel Corrode Much More Than Aluminium P2

Aliminum doesn corrode when it's wer.  This is a bit odd because aluminium is more reactive then iron.  What happens is that the aluminium reacts very quickly with oxygen in the air to form aluminium oxide.  A nice protective layer of aluminium oxide sticks firmly to the aluminium below and stops any further reaction taking place (the oxide isnt crumb ly and flaky like the rush, so it wont fall off). 

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Car Bodies:Aluminium Or Steel?

Aluminium has two big advantages over steel:

1) It had much lower denisty, so the car body of an aluminum car will be lighter than the same car made of steel.  This gived the aluminium car much better fuel economy, which saves fuel resources.

2) A car body made with aluminium corrodes less and so it'll have a longer lifetime.  

But aluminium has a massive disadvantage.  It costs an awful lot more than steel.  This is why car manufaturers build cars out of steel - comes down to money

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You Need Various Materials To Build Different Bits

1) Steel is strong and it can be hammered into sheets ans welded together - good for the body work.

2) Copper's a good electrical conductor and can be pulled into wires - it's used for the electrical wiring.

3) Aluminium's strong and has a low density - it's used for parts of the engine, to reduce weight.

4) Glass is transparent - cars need windscreens and windows.

5) Plastics are light and hardwearing, so they're used as internal coverings for doors, dashboards etc, they're also electrical insulators, so they're used to cover theats and floor.

6) Fibres (natural and saynthetic) are hard - wearing, so they're used to cov er the seat and floor.

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Recycling Cars Is Important

1) As with all recycling, the idea is to save natural resources, save money, reduce landfill use.

2) At the moment a lot of the metal from a scrap car is recycled, though most of the other materials (e.g. plastic tubber) go into landfill.  But european laws are now in place saying that 85% of the materials in a car (rising to 95% of a car by 2015) must be reyclable.

3)The biggest problem with recycling all the non-metal bits of a car is that they have to be separated befoer they can be recycled.  Sorting out different types of plastic is pain in the neck.

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