Mercury and it's Extraordinary Properties
the only element which is liquid at standard temperature and pressure gathers
so much interest for its extra-ordinary properties.
Ever wondered why it has the symbol Hg which is nowhere in it’s commonly known name?
It was conventionally called as “Hydrargyrum.” Faced difficulty in pronouncing?? That’s
the reason for its much easier to pronounce name “Mercury.” The term
hydrargyrum comprises of two Greek letters, “hydror” which means water and “argyros”
which means silver. This term is based on its liquid consistency and silver colour.
Its density is significantly higher than most of the
metals. Its melting point is around -39 ֯C, which is way too below the room
temperature. It is a hard-solid mass at temperatures equal to or below -39 ֯C, but starts melting as soon as it is
brought to room temperature. Alike it’s melting point, its boiling point is
also relatively low than most of the metals. Because it has low boiling point (compared
to other metals) of 360 ֯C,
it can be purified using distillation. But make sure to not try this at home!!!
There’re strong metallic bonding forces between
mercury atoms, and thus its surface tension is really high. Because of its high
surface tension, the mercury droplets are drawn in a way to minimise its
surface area, and is ideally is spherical in shape. Small droplets are quite
circular in shape as compared to larger droplets.
Additionally, as it is a metal, it can also conduct electricity
and that is the base of many mercury based electrical switches. Tilt switch is
the most common of all.
In nature, it is found in the form of mercury sulphide
or cinnabar and is found in two colours, the alpha form is red in colour, while
the beta form is black. The red one is strongly pigmented and is thus used as
pigment known as vermillion.
Now that’s one reason why no mercury vermillion is
highly preferred now-a-days.
They can be converted into mercury metal by roasting.
Chemically, mercury can be extracted from mercury sulphide by dissolving in strongly
basic solutions of sodium sulphide.
Mercury can amalgamate almost all metals, except some
like iron, platinum, tungsten and tantalum.
The amalgamation of aluminium is widely known.
Aluminium is protected with a layer of aluminium
oxide. Mercury disrupts the protective aluminium oxide layer and exposes pure aluminium
to air which causes aluminium to react quickly and form aluminium oxide which
grows as white fibres. This releases mercury form amalgam, which combines with
more aluminium and continues the vicious cycle.
Because of this, it is advised to never carry any amount
of mercury in an airplane!!!
This amalgamation reaction is commonly used for
Metallic mercury is seldom utilised in its elemental
form, more soluble mercury salt is used instead. Mercury amalgamation is useful
for extracting gold from gold ores or to make dental fillings.
It is not really toxic and is poorly absorbed into the
skin. The most dangerous thing about mercury vapor is mercury vapor. The vapor
can be absorbed by the lungs so don’t dare to breathe it in.
To know more about toxic effects or mercury, check out
the upcoming blogs.