F. U. N with Science F.U.N With Science_1_FINAL_UPDATE v3 | Page 16

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Electroplating
Electroplating (Figure 3)
is the process of coating
one metal with another
metal by using electrol-
ysis. It is usually done to
improve the appearance
of the metal or prevent
the corrosion of the
metal, e.g. iron is often
plated with chromium to
prevent it from rusting.
The object to be plated
is placed at the cathode,
while the anode is the
particular metal to coat
the object. The electrolyte
solution must also contain
ions of the same metal for
plating. During electroly-
sis, the anode will dissolve
into the solution. The ions
produced will move to
the cathode where they
are discharged and de-
posited as a layer on the
cathode. It is important to
ensure that the cathode
is electrically conductive,
to ensure that the electro-
lytic process is feasible.
Figure 3: Example of Electrolytic Cell for Electroplating
Metal extraction and electroplating are the two main
usages of electrolysis. Other applications include elec-
trorefining and anodising. Electrorefining is a process
which can be used to increase the purity of a met-
al. It is used in the production of copper, nickel, lead,
gold, and silver. The impure sample of the metal to be
purified is placed at the anode and a pure sample is
used as the cathode and using a similar principle of
electroplating, in that only the metal ions dissolve from
the anode and deposit at the cathode. Anodising, also
similar to electroplating but taking place at the anode,
is used to increase the thickness of the natural oxide
layer on the surface of a metal, say Aluminium, in a
process called passivation. This gives the aluminium
extra corrosion resistance.
by Modibo Holder