subject = Chemistry
title = Platinum
Platinum is a relatively rare, chemically inert, metallic element. It symbol
is Pt, atomic number is 78, and its atomic weight is 195.09. Platinum is one
of the heaviest substances known. One cubic foot of Platinum weighs 21 times
as much as a cubic foot of water. A grayish-white metal, Platinum has a melting
point of 1772 degrees C and a realatively high boiling point of 3827 degrees
C. It has a high fusing point, is ductile and malleable, expands slightly
upon heating, and has high electrical resistance. Platinum is seldom used
in its pure stage because it is too soft. The third most ductile metal, it
can be drawn into a thread one twenty thousandth part of an inch in thickness.
It is extremely resistant to attack by air, water, single acids and ordinary
reagents, but does dissolve in hot aqua regia, a mixture of nitric and hydrochloric
acids. Platinum has the unusual property of being able to absorb large amounts
of hydrogen at ordinary temperatures and resist it at high temperatures.
The first mention of Platinum occurs in the writings of an Italian physician
and poet named Julius Caesar Salinger in 1557. A hieroglypic character made
froma grain of Platinum dated back to the 7th century. Credit for discovery
of Platinum has been given to Don Antonio de Ulloa, a young lieutenant in the
Spanish Navy. The metal was referred to as the “platina de Pinto”, meaning
the siver like metal from the Pinto River. The first thorough study of Platinum
was conductd in1750 by the English physician William Brownrigg. Brownrigg
noted that Platinum was heavier and even more chemically inert than Gold was.
Platinum forms useful alloys with many other metals, including Iridium,
Palladium, Rhodium, Ruthenium, Osmium, Gold, Nickel, Cobalt, and Tungsten.
At high temperatures Platinum also reacts with Chlorine, Fluorine, Phosphorus,
Arsenic and Sulfur. Among the transition metals, Platinum has the greatest
tendencies to bond directly with Carbon.
Platinum is used extensively
in modern industrial society because of its chemical inertness, high melting
point, and extraordinary catalytic properties. platinum is valuable for laboratory
apparatus, such as tongs, combustion boats, crucibles and evaoporating dishes.
It is also used for thermometers in furnaces, for electrodes in making quantitative
chemical analyses, and for corrosion and heat-resistant instruments. Platinum
is used extensively in the jewelry industry for setting diamonds and other
precious stones. Rocket and jet engine parts often contain Platinum alloys
because they must withstand high temperatures for long periods of time. At
petroleum refineries, finely divided Platinum is used as a catalyst in upgrading
the octane of gasoline. In automobiles, converters containing Platinum-Palladium
alloys reduce air pollution from exhaust gases. High quality optical glass
for television picture tubes and eyeglasses is melted in pots lined with nonreactive
Platinum alloys. A form of Platinu
m,cisplatin, stops cancer cell division
and disrupts its growth pattern.