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7440-22-4

Name Silver
CAS 7440-22-4
EINECS(EC#) 231-131-3
Molecular Formula Ag
MDL Number MFCD00003397
Molecular Weight 107.87
MOL File 7440-22-4.mol

Chemical Properties

Definition Metallic element, atomic number 47, group IB of the periodic table, aw 107.868, valence of 1, two stable isotopes.
Appearance Silver is a white lustrous metal that is extremely ductile and malleable.
Melting point  960 °C(lit.)
Boiling point  2212 °C(lit.)
density  1.135 g/mL at 25 °C
vapor density  5.8 (vs air)
vapor pressure  0.05 ( 20 °C)
refractive index  n20/D 1.333
Fp  232 °F
storage temp.  2-8°C
solubility  H2O: soluble
form  wool
color  Yellow
Specific Gravity 10.49
Odor Odorless
Stability: Stable. Substances to be avoided include strong acids and strong bases, tartaric acid, oxalic acid. Blackened by contact with ozone, hydrogen sulfide, sulfur. Powder is highly flammable.
Resistivity 1-3 * 10^-5 Ω-cm (conductive paste) &_& 1.59 μΩ-cm, 20°C
Water Solubility  insoluble
Sensitive  Light Sensitive
Merck  13,8577
Exposure limits TLV-TWA (metal dusts and fumes) 0.1 mg/m3 (ACGIH), 0.01 mg/m3 (MSHA and OSHA), soluble compounds 0.01 mg/m3 (AIGIH).
History Slag dumps in Asia Minor and on islands in the Aegean Sea indicate that man learned to separate silver from lead as early as 3000 B.C. Silver occurs native and in ores such as argentite (Ag2S) and horn silver (AgCl); lead, lead-zinc, copper, gold, and copper-nickel ores are principal sources. Mexico, Canada, Peru, and the U.S. are the principal silver producers in the western hemisphere. Silver is also recovered during electrolytic refining of copper. Commercial fine silver contains at least 99.9% silver. Purities of 99.999+% are available commercially. Pure silver has a brilliant white metallic luster. It is a little harder than gold and is very ductile and malleable, being exceeded only by gold and perhaps palladium. Pure silver has the highest electrical and thermal conductivity of all metals, and possesses the lowest contact resistance. It is stable in pure air and water, but tarnishes when exposed to ozone, hydrogen sulfide, or air containing sulfur. The alloys of silver are important. Sterling silver is used for jewelry, silverware, etc. where appearance is paramount. This alloy contains 92.5% silver, the remainder being copper or some other metal. Silver is of utmost importance in photography, about 30% of the U.S. industrial consumption going into this application. It is used for dental alloys. Silver is used in making solder and brazing alloys, electrical contacts, and high capacity silver–zinc and silver–cadmium batteries. Silver paints are used for making printed circuits. It is used in mirror production and may be deposited on glass or metals by chemical deposition, electrodeposition, or by evaporation. When freshly deposited, it is the best reflector of visible light known, but is rapidly tarnishes and loses much of its reflectance. It is a poor reflector of ultraviolet. Silver fulminate (Ag2C2N2O2), a powerful explosive, is sometimes formed during the silvering process. Silver iodide is used in seeding clouds to produce rain. Silver chloride has interesting optical properties as it can be made transparent; it also is a cement for glass. Silver nitrate, or lunar caustic, the most important silver compound, is used extensively in photography. While silver itself is not considered to be toxic, most of its salts are poisonous. Natural silver contains two stable isotopes. Fifty-six other radioactive isotopes and isomers are known. Silver compounds can be absorbed in the circulatory system and reduced silver deposited in the various tissues of the body. A condition, known as argyria, results with a greyish pigmentation of the skin and mucous membranes. Silver has germicidal effects and kills many lower organisms effectively without harm to higher animals. Silver for centuries has been used traditionally for coinage by many countries of the world. In recent times, however, consumption of silver has at times greatly exceeded the output. In 1939, the price of silver was fixed by the U.S. Treasury at 71¢/troy oz., and at 90.5¢/troy oz. in 1946. In November 1961 the U.S. Treasury suspended sales of nonmonetized silver, and the price stabilized for a time at about $1.29, the melt-down value of silver U.S. coins. The Coinage Act of 1965 authorized a change in the metallic composition of the three U.S. subsidiary denominations to clad or composite type coins. This was the first change in U.S. coinage since the monetary system was established in 1792. Clad dimes and quarters are made of an outer layer of 75% Cu and 25% Ni bonded to a central core of pure Cu. The composition of the oneand five-cent pieces remains unchanged. One-cent coins are 95% Cu and 5% Zn. Five-cent coins are 75% Cu and 25% Ni. Old silver dollars are 90% Ag and 10% Cu. Earlier subsidiary coins of 90% Ag and 10% Cu officially were to circulate alongside the clad coins; however, in practice they have largely disappeared (Gresham’s Law), as the value of the silver is now greater than their exchange value. Silver coins of other countries have largely been replaced with coins made of other metals. On June 24, 1968, the U.S. Government ceased to redeem U.S. Silver Certificates with silver. Since that time, the price of silver has fluctuated widely. As of January 2002, the price of silver was about $4.10/troy oz. (13¢/g); however the price has fluctuated considerably due to market instability. The price of silver in 2001 was only about four times the cost of the metal about 150 years ago. This has largely been caused by Central Banks disposing of some of their silver reserves and the development of more productive mines with better refining methods. Also, silver has been displaced by other metals or processes, such as digital photography.
Uses
This malleable white metal is found as argentite (Ag2S) and horn silver (AgCl) or in lead and copper ore. Copper plates coated with a thin layer of elemental silver and fumed with iodine were used by Niépce and Daguerre. Aside from the heliograph and physautotype, silver halide compounds were the basis of all photographic processes used in the camera and most of the printing processes during the 19th century.
CAS DataBase Reference 7440-22-4(CAS DataBase Reference)
NIST Chemistry Reference Silver(7440-22-4)
EPA Substance Registry System 7440-22-4(EPA Substance)

Safety Data

Hazard Codes  N,Xn,T
Risk Statements 
R22:Harmful if swallowed.
R38:Irritating to the skin.
R20/21:Harmful by inhalation and in contact with skin .
R10:Flammable.
R40:Limited evidence of a carcinogenic effect.
R34:Causes burns.
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed .
Safety Statements 
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S24/25:Avoid contact with skin and eyes .
S25:Avoid contact with eyes .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S23:Do not breathe gas/fumes/vapor/spray (appropriate wording to be specified by the manufacturer) .
RIDADR  UN 3264 8/PG 3
WGK Germany  3
RTECS  VW3500000
8
TSCA  Yes
HazardClass  6.1
PackingGroup  III
HS Code  71069110
Safety Profile
Human systemic effects by inhalation: skin effects. Inhalation of dusts can cause argyrosis. Questionable carcinogen with experimental tumorigenic data. Flammable in the form of dust when exposed to flame or by chemical reaction with C2H2, NH3, bromoazide, ClF3 ethyleneimine, H2O2, oxalic acid, H2SO4, tartaric acid. Incompatible with acetylene, acetylene compounds, aziridine, bromine azide, 3-bromopropyne, carboxylic acids, copper + ethylene glycol, electrolytes + zinc, ethanol + nitric acid, ethylene oxide, ethyl hydroperoxide, ethyleneimine, iodoform, nitric acid, ozonides, peroxomonosulfuric acid, peroxyformic acid. See also POWDERED METALS and SILVER COMPOUNDS.
Hazardous Substances Data 7440-22-4(Hazardous Substances Data)
Toxicity
PEL (OSHA) 0.01 mg/m3
TLV-TWA (ACGIH) 0.1 mg/m3 (silver metal)
TLV-TWA (ACGIH) 0.01 mg/m3 (soluble silver compounds, as Ag)
IDLA 10 mg Ag/m3

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