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Saturday, 4 June 2011

Properties of pure silver

Anglo-Saxon: siolful (silver);

Symbol from Latin: argentum. Ag
Item from the first group of the periodic table
Atomic number 47
atomic weight 107.868
Density of 10.5 g / cm ³
Melting point 1234.93 K, 961.78 °C, 1763.2°F
Boiling point 2435 K, 2162 °C, 3924 °F
Brinell hardness HB 26
Ritz Mohs hardness: 2.7 (pure silver)
Color: clear white
most important sites: Russia, Mexico, Peru

Silver is a white metal which all other metals on the brightness
Color, conductivity
of heat and electricity, polishing ability, and reflectivity exceeds them. Since there long wavelength light (red, orange, yellow) more fully reflected as short-wave, it has a "warm" color - such as in contrast to the "cold" chrome. Silver reached almost the ductility of gold. It can be hit films of only 0.0002 mm thickness. These "silver leaf" is translucent and bluish green. From 1 g of silver can pull a wire of 2000 m length. This great stretch, which is second only to gold also with the low hardness of the silver, which is between the copper and gold and a Mohs hardness of about 3 corresponds to declare.
Silver reacts with oxygen in the solid state by forming an invisible layer of silver oxide, the thickness of one molecule and reaches only acts as a protective layer. The presence of these very small scale water-soluble oxide layer allows the formation of silver ions, the water content in germicidal effect. In this way, can be explained that not only supplements in the form of silver colloidal solutions , eg collargol, but also equipment, cutlery and silver coins from oligodynamic (ie sterilizing) have an effect.
The affinity of the silver to sulfur is particularly high. In conjunction with the in populated areas is always present in trace sulphide silver forms a layer of silver sulfide. This is a major cause of tarnishing of silver. Another consequence of the affinity for sulfur is the sometimes uncomfortable-looking metal smell of silver, which is due to the action of organic sulfur compounds.
By non-oxidizing acids (eg hydrochloric acid) and organic acids, silver is not attacked. Concentrated sulfuric acid dissolves silver only in the heated state. Best solution for silver is nitric acid. Since gold is not attacked by nitric acid, gold and silver can be prepared by dissolving the silver in nitric acid (nitric acid) are separated from each other. In contrast, silver is not in aqua regia (see below) are soluble.
Since pure silver for most applications is too soft, it is alloyed with other metals. It forms amalgams with mercury, which are now primarily used in dentistry.

Silver is due to its excellent physical properties to a large extent also used industrially and in demand (including photographic technology, electrical engineering, dental supplies, mirror coatings, medical technology).

aquaregia , is a solution of three parts concentrated hydrochloric acid and one part concentrated nitric acid.

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