Page 43 - Curriculum Visions Dynamic Book

Using gold in industry
Gold is almost entirely nonreactive. Although this means
that gold will not form compounds, it also means that, where nonreactive materials are needed, gold has an important part to play. Because it is rare, it is also expensive to use. This is why gold is used only where such materials are important.
Gold is a good conductor of electricity and does not oxidise, so it is important for use in electrical circuits, such as micro-electronics, and for connectors and switches. Most of the gold used is electroplated on to some less expensive base material.
Also, because it doesn’t corrode, gold is used in places where there are corrosive atmospheres such as in certain chemical processes. For the same reason, gold can be used safely in amalgams to make dental fillings.
Gold can also have an important role in tiny amounts. For example it is used in glass to produce a heat shield.
alloy: a mixture of a metal and various other elements.
electrolysis: an electrical–
chemical process that uses an electric current to cause the
break up of a compound and
the movement of metal ions in
a solution. The process happens
in many natural situations
(as for example in rusting) and
is also commonly used in industry for purifying (refining) metals
or for plating metal objects with
a fine, even metal coating.
electrolyte: a solution that conducts electricity.
electroplating: depositing a thin layer of a metal onto the surface of another substance using electrolysis.
Gold plating
Gold can be deposited as a fine layer on the surface of many materials. Usually it is applied by electrolysis after being dissolved in a cyanide solution. The thickness of gold plate obtained this way can be as little as two- millionths of a centimetre.
Some metals become coated with gold automatically if they are dipped in a gold cyanide solution, because a natural battery is established between the gold and the metal. Gold can be deposited on to nickel in this way.
 Gold does not oxidise, so no insulating oxide layer builds up on
its surface (as happens, for example, with aluminium). This is the reason
gold plated contacts are used in many electrical circuits where it is important that good long-term contact is made.
This is a terminator from a computer.
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