Senin, 22 Agustus 2011

General properties of tin (Sn)

Tin is a chemical element that has the symbol Sn and atomic number 50. Tin in English called a Tin. The word "Tin" is taken from the name of the Etruscan god "Tinia". Latin name of the lead is "Stannum" where the word is associated with the word "stagnum" which in English is synonymous with the word "dripping" which means to be a liquid / wet, the use of this word is connected with a metal tin that is easy to melt.
Ordinary tin is formed by nine stable isotopes. There are 18 other isotopes that diketahui.Timah a silvery white metal, with a low hardness, can be forged ("malleable"), has the properties of thermal and electrical conductivity are high, relatively soft, corrosion resistant and has a low melting point and have the structure crystal is high. If this structure is broken, a voice that is often called (weeping tin) when an element is bent.
Tin forms:

This element has 2 forms alotropik at normal pressure. When heated, lead gray (lead-alpha) with a cubic structure unchanged at 13.2 degrees Celsius into tin (tin beta) which has a tetragonal structure. When the tin is cooled to a temperature of 13.2 degrees Celsius, he slowly changed from white to gray. These changes are caused by impurities (impurities) such as aluminum and zinc, and can be prevented by adding antimony or bismuth. Gray tin has little usefulness. Tin can be polished very slippery and is used to cover other metals to prevent corrosion and chemical action. Thin layer of tin on the steel used to make food last.
Tin alloy is very important. Soft solder, bronze, Babbit metal, bell metal, white metal, alloy formation and phosphor bronze is an alloy containing some lead.
Tin can withstand sea water that has been distilled and tap water, but easily attacked by strong acids, alkali and acid salts. Oxygen in a solution can accelerate the action of chemicals such attacks. If heated in air, tin forms Sn2, slightly acid, and forming stannate salts with oxides. The most important salt is chloride, which is used as reducing agents. Tin salts are sprayed onto glass are used to make electrical conductor layer. This application has been used for the windshield that resists freezing. Most window glass is now made by floating molten glass on the molten tin to form a flat surface (Pilkington process).
Recently, a mixture of crystalline tin-niobium metal becomes superconducting at very low temperatures, making it as a construction material that promises a superconductive magnet. Magnet, which is made by tin-niobium wire weighs only a few pounds but with a small battery can produce a magnetic field similar to electromagnetic force of 100 tons carried by large power sources.

ž Sources Tin (Sn) on Earth
The minerals contained in the ore is generally the major minerals, namely cassiterite. Tin was not found in the element of free will on earth but is acquired from senyawaannya. Tin at present be obtained from the mineral cassiterite or tinstone. Cassiterite is a mineral of tin oxide SnO2, with a lead content ranging from 78%. Other examples of other sources of tin ore and received less attention than the sulfide mineral cassiterite is a complex that is stanite (Cu2FeSnS4) is a mineral complex of copper-tin-iron-sulfur and cylindrite (PbSn4FeSb2S14) is a mineral complex of timbale-tin-iron-antimony- sulfur are two examples of this mineral usually found in tandem with other metallic minerals such as silver.
Tin is an element of the 49th most abundant in the earth's crust where the tin has a content of 2 ppm compared with 75 ppm zinc, copper 50 ppm and 14 ppm for lead. Cassiterite is found in alluvial deposits / alluvium is soil or sediment that are not consolidated to form slabs of stone which can be settled at the bottom of the sea, rivers or lakes. Alluvium consists of various minerals such as sand, clay, and small rocks. Almost 80% of production is obtained from the alluvial tin / alluvium or the term secondary deposits. Chance to get 1 kg Cassiterite then about 7 tons of tin ore served until 8 / alluvial cassiterite be mined due to very low concentrations.
Tin earth unevenly spread but there are in one geographic area where there is an important resource in Southeast Asia including China, Myanmar, Thailand, Malaysia, and Indonesia. The results obtained are not so much of Peru, South Africa, UK, and Zimbabwe.
General properties of tin (Sn)
ü Lead a whitish metallic silver,
ü ductile and have a high crystalline structure,
ü In normal circumstances (13 - 160 ° C), the metal is shiny and malleable.
ü Lead is also not easily oxidized in air so that the stainless.
ü Found in many alloys, and used to coat other metals to prevent rust.

Physical properties of tin (Sn)
ü state of matter: Solid
ü Melting point: 505.08 K (449.47 ° F)
ü Boiling Point: 2875 K (4716 ° F)
ü Density: 7.365 g/cm3 (white Sn) 5.769 g/cm3 (gray Sn)
molar volume ü: × 10-6 m3/mol 16:29
ü Heat of vaporization: 295.8 kJ / mol
ü Heat of fusion: 7029 kJ / mol
ü Heat type: 27.112 J / molK
ü Heat of fusion: 7.03 kJ / mol
ü Vapor pressure: 5.78 E-21 Pa at 505 K
ü The speed of sound: 2500 m / s at 293.15 K

Mechanical properties of tin (Sn)
ü low-power appeal, approximately 2000 psi
ü Youngnya modulus is 5.9 to 7.8 x 10 ^ 6 psi
ü Strength Brinell Mohs 1.8 or 5.0 (1000 kg, 10 mm)

Chemical properties of tin (Sn)
ü atomic weight: 118 710 sma
ü density: 7.3 g/cm3
ü atomic radius: 145 (145) pm
ü covalent radius: 141 pm
ü The radius of the van der Waals: 217 pm
ü electron configuration: [Kr] 4d10 5s2 5p2
ü Electrons per energy level: 2, 8, 18, 18, 4
ü oxidation: 4.2, -4
ü Atomic number: 50
ü Number of mass: 118.71
ü electronegativity: 1.96 (scale Pauli)
ü 1st ionization energy: 708.6 kJ / mol
ü 2nd ionization energy: 1411.8 kJ / mol
ü 3rd ionization energy: 2943.0 kJ / mol
ü atomic radius: 140 pm
ü covalent radius: 139 pm
ü The radius van der Waals: 217 pm
ü Crystal structure: tetragonal (Sn white) cubic diamond (gray Sn)
ü thermal conductivity: 66.8 W / mK
ü lunah Tin is a metal, flexible, and the color is gray metallic. Tin is not easily oxidized and resistant to corrosion caused by the formation of tin oxide coating that inhibits further oxidation process. Tin is resistant to corrosion distilled water and sea water, but can be attacked by strong acids, alkalis, acids and salts. Oxidation process is accelerated by increasing the oxygen content in solution.
ü If the tin is heated in the presence of air it will form SnO2.
ü Tin exists in two allotropes of tin alpha and beta. Tin alfa-called gray tin and stable temperature below 13.2 ° C with covalent bonding structure such as diamond. While white beta tin and metal is stabilized at high temperatures, and is as a conductor.
ü Lead dissolved in HCl, HNO3, H2SO4, and some organic solvents such as acetic acid oxalic acid and citric acid. Tin is also soluble in strong base such as NaOH and KOH.
ü Tin generally have oxidation number +2 and +4. Tin (II) tend to have metallic properties and easily obtained from the dissolution of Sn in hot concentrated HCl.
ü Lead directly react with chlorine to form Sn (IV) chloride.
ü tin hydrides are stable only SnH4.

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