L18 - Iron and Aluminium

							Iron and Aluminium


       Miss Jan
Iron and aluminium SLOs
 investigate the reactions of iron and
  aluminium with oxygen, water, and
  acids
 be able to explain the different
  reactivity of these two metals
    Rusting experiment




Number 1-7 down the page – record
observations
Results
 Things needed for rusting are:
Oxygen and water (and of course, iron)
 Conditions that speed up rusting
 are:
Salt, exposure to oxygen
 Conditions that slow down rusting
 are: Sacrificial metal, dry air
    “Iron and Aluminium” sheet
   Answer the true or false questions
                                       Fe
F 1A The chemical symbol for iron is Ir.
T 1B Iron is produced when iron oxide
   reacts with carbon.
T 1C The other product formed when iron
   oxide is reduced is carbon dioxide.
F 1D Salt is necessary for rusting to occur.
F 1E Rust is iron sulfide.
                  oxide
T 2A Aluminium is produced at Tiwai
  Point in Southland.
F 2B Aluminium is used in power wires
  because it is a good conductor of
  electricity
  heat.
F 2C Aluminium can be made by
  reducing aluminium oxide with carbon.
   Chemical reduction
F 2D Aluminium is a very unreactive
  metal.
  Iron rust is
   porous –
allows oxygen
 to enter the
 metal, which
  allow more
     rusting
Rusting Aluminium?
 Aluminum is actually very prone to
 corrosion. However, aluminum
 corrosion is aluminum oxide, a
 very hard material that actually
 protects the aluminum from
 further corrosion. Aluminum oxide
 corrosion also looks a lot more like
 aluminum, so it isn't as easy to
 notice as rusted iron.
“How to prevent rusting” sheet
 Each table group read through and
 summarize one method of
 preventing rust. Then report to back
 to the class – report should contain:
   What is this method?
   How does it work?
Sacrificial metal

                    To be bolted
                    onto the hull
                    of the boat


                    Why is it
                    labeled “do
                    not paint”?
Galvanised iron


                  Coat of zinc –
                  prevent water
                  or oxygen from
                  reacting with
                  iron
Electroplating


                 Chrome and
                 nickel
                 coating
Questions about rusting
1. Iron oxide
2. Iron, water, oxygen
3. Iron + oxygen  iron oxide
4. Brass (Cu + Zn) does not rust.
   Steel (99% Fe) rusts
5. Painting provides a barrier to
   water and oxygen, preventing
   them from reacting with iron
6. Two sacrificial metals: magnesium
   and zinc
7. Hull of ship or drilling platform, hot
   water heater
8.
9. Zinc
10. Zinc prevents water or oxygen
     from reaching iron. Also acts as
     sacrificial metal (will corrode before
     iron)