Chemistry Reference
In-Depth Information
tube 1
(control
experiment)
tube 2
tube 3
tube 4
dry
air
pure
oxygen
air
air
layer of
olive oil
(prevents air
dissolving in
the water)
very
rusty
iron nails
rusty
iron
nails
distilled
water
anhydrous
calcium chloride
(drying agent)
boiled distilled
water (boiled to
remove any
dissolved oxygen
from the air)
distilled
water
Figure 10.20
Rusting experiment with nails.
Figure 10.22
A brand new car is protected against corrosion (top).
However, if the paintwork is damaged, then rusting will result.
Oiling/greasing
The iron and steel in the moving parts of machinery
are coated with oil to prevent them from coming
into contact with air or moisture. This is the
most common way of protecting moving parts of
machinery, but the protective film must be renewed.
Coating with plastic
The exteriors of refrigerators, freezers and many
other items are coated with plastic, such as PVC, to
prevent the steel structure rusting (Figure 10.23).
Figure 10.21
Painting keeps the air and water away from the steel used
to build a ship.
the iron beneath it will start to rust (Figure 10.22)
and corrosion can then spread under the paintwork
which is still sound. This is why it is essential that
the paint is kept in good condition and checked
regularly.
Plating
Cans for food can be made from steel coated with
tin. The tin is deposited on to the steel used to
make food cans by dipping the steel into molten tin.
