Zinc , with CAS number of 7440-66-6, can be called Asarco L 15 ; Blue powder ; CCRIS 1582 ; Emanay zinc dust ; Granular zinc ; Lead refinery vacuum zinc ; Rheinzink ; Merrillite .
The metal is hard and brittle at most temperatures but becomes malleable between 100 and 150 °C. Above 210 °C, the metal becomes brittle again and can be pulverized by beating. Zinc is a fair conductor of electricity. For a metal, zinc has relatively low melting (419.5 °C, 787.1 F) and boiling points (907 °C). Its melting point is the lowest of all the transition metals aside from mercury and cadmium.
Many alloys contain zinc, including brass, an alloy of copper and zinc. Other metals long known to form binary alloys with zinc are aluminium, antimony, bismuth, gold, iron, lead, mercury, silver, tin, magnesium, cobalt, nickel, tellurium and sodium. While neither zinc nor zirconium are ferromagnetic, their alloy ZrZn2 exhibits ferromagnetism below 35 K.
1. History
1). Ancient use
Various isolated examples of the use of impure zinc in ancient times have been discovered.Ornaments made of alloys that contain 80–90% zinc with lead, iron, antimony, and other metals making up the remainder, have been found that are 2500 years old.
2). Early studies and naming
Zinc was distinctly recognized as a metal under the designation of Fasada in the medical Lexicon ascribed to the Hindu king Madanapala and written about the year 1374. Smelting and extraction of impure zinc by reducing calamine with wool and other organic substances was accomplished in the 13th century in India.The Chinese did not learn of the technique until the 17th century.
Some alchemists called zinc oxide lana philosophica, Latin for "philosopher's wool".a Swiss-born German alchemist referred to the metal as "zincum" or "zinken" in his book Liber Mineralium II, in the 16th century. The metal was also called Indian tin, tutanego, calamine, and spinter.
3). Isolation of the pure element
William Champion's brother, John, patented a process in 1758 for calcining zinc sulfide into an oxide usable in the retort process. Prior to this only calamine could be used to produce zinc. In 1798, Johann Christian Ruberg improved on the smelting process by building the first horizontal retort smelter. Jean-Jacques Daniel Dony built a different kind of horizontal zinc smelter in Belgium, which processed even more zinc.
Italian doctor Luigi Galvani discovered in 1780 that connecting the spinal cord of a freshly dissected frog to an iron rail attached by a brass hook caused the frog's leg to twitch.The galvanic cell and the process of galvanization were both named for Luigi Galvani and these discoveries paved the way for electrical batteries, galvanization and cathodic protection.
Galvani's friend, Alessandro Volta, continued researching this effect and invented the Voltaic pile in 1800.The basic unit of Volta's pile was a simplified galvanic cell.
The non-magnetic character of zinc and its lack of color in solution delayed discovery of its importance to biochemistry and nutrition. This changed in 1940 when carbonic anhydrase, an enzyme that scrubs carbon dioxide from blood, was shown to have zinc in its active site. The digestive enzyme carboxypeptidase became the second known zinc-containing enzyme in 1955.
2. Uses
Zinc (CAS NO.7440-66-6) metal is most commonly used as an anti-corrosion agent. The zinc metal was used for galvanization, which is used on chain-link fencing, guard rails, suspension bridges, lightposts, metal roofs, heat exchangers, and car bodies. Zinc is also used to cathodically protect metals that are exposed to sea water from corrosion. With an electrochemical potential of ?0.7618 volts, zinc makes a good material for the negative terminus or anode in batteries.Powdered zinc is used in this way in alkaline batteries and sheets of zinc metal form the cases for and act as anodes in zinc-carbon batteries.
A widely used alloy of zinc is brass, which is useful in communication equipment, hardware, musical instruments, and water valves. Other widely used alloys that contain zinc include nickel silver, typewriter metal, soft and aluminum solder, and commercial bronze.Zinc is also used in contemporary pipe organs as a substitute for the traditional lead/tin alloy in pipes. Alloys of primarily zinc with small amounts of copper, aluminium, and magnesium are useful in die casting as well as spin casting, especially in the automotive, electrical, and hardware industries.
Zinc oxide is widely used as a white pigment in paints, and as a catalyst in the manufacture of rubber. It is also used as a heat disperser for the rubber and acts to protect its polymers from ultraviolet radiation. Zinc chloride can be used as a wood preservative.It is also used to make other chemicals. Zinc methyl (Zn(CH3)2) is used in a number of organic syntheses.Zinc sulfide (ZnS) is used in luminescent pigments such as on the hands of clocks, X-ray and television screens, and luminous paints.Crystals of ZnS are used in lasers that operate in the mid-infrared part of the spectrum. Zinc sulphate is a chemical in dyes and pigments. Zinc pyrithione is used in antifouling paints. Zinc powder is sometimes used as a propellant in model rockets.Zinc sheet metal is used to make zinc bars.
Zinc is included in most single tablet over-the-counter daily vitamin and mineral supplements. Zinc gluconate glycine and zinc acetate are used in throat lozenges or tablets to reduce the duration and the severity of cold symptoms. Zinc lactate is used in toothpaste to prevent halitosis.
3. Production
Roasting converts the zinc sulfide concentrate produced during processing to zinc oxide:
2ZnS + 3 O2 → 2ZnO + 2SO2
Pyrometallurgy processing reduces zinc oxide with carbon or carbon monoxide at 950 °C (1,740 °F) into the metal, which is distilled as zinc vapor.
2 ZnO + C → 2 Zn + CO2
2 ZnO + 2CO → 2 Zn + 2 CO2
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