Friday, January 9, 2015

Chromium, a chemical symbol Cr, (lat. Chromium) is pale white, shiny, very hard and brittle metal a

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Chromium, a chemical symbol Cr, (lat. Chromium) is pale white, shiny, very hard and brittle metal at the same time. It is used in metallurgy in the production of alloy steels joint strike fighter and other alloys, a thin layer of chromium metal objects protects the surface against corrosion and increases their hardness. Chromium is the hardest elemental metal and is characterized by extremely low reactivity and high chemical resistance. It was discovered in 1797 by Louis Nicolas Vauquelin. Among transition elements having valence electrons in d-sphere.
Despite its significant chemical stability with chromium dissolves slowly in the non-oxidizing acids (hydrochloric acid), while the acid oxidizing action passivate the metal surface. Chromium is oxidized by heating in oxygen flame, or oxidizing agents such as nitrates, or chlorates. Directly also combines joint strike fighter with halogens, sulfur, nitrogen, carbon, silicon, boron, and certain metals, but only for heat.
Chromium is among the elements with a relatively high proportion of the Earth and in space. The earth's crust is about average chromium content from 0.1 to 0.2 g / kg. In salt water, its concentration varies only at a level of 0.05 micrograms per liter. It is assumed that in the universe there is one atom of chromium approximately 3 million hydrogen atoms.
In nature chromium occurs very often simultaneously ores such as iron ore as chromite, chemically double oxide-chromium iron FeO. Cr2O3. Another important mineral chromium is krokoit, chemically lead chromate joint strike fighter PbCrO4. Small amounts of chromium contribute to discoloration gemstones emeralds and rubies.
The world's largest reserves of chromium are in South Africa, which produces about half of the total world production of this metal. Other outstanding chrome producers are Kazakhstan, India and Turkey.
The largest share of global production of chromium clearly finds use in the metallurgical joint strike fighter industry, mainly in the production joint strike fighter of alloy steels. The chromium content in the alloy primarily determines the hardness and mechanical resistance.
In everyday life we meet with chromium rather like material, protecting joint strike fighter metal surfaces from corrosion for simultaneous increase their aesthetic appearance. joint strike fighter A classic example is the plating of surgical instruments and other devices used in medicine (sterilizers, dental equipment and similar items used for examination of the patient). joint strike fighter In civilian life, find objects joint strike fighter often in chrome bathroom fixtures, as part of a luxury car accessories and many other applications.
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