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20816-12-0

Name Osmium tetraoxide
CAS 20816-12-0
EINECS(EC#) 244-058-7
Molecular Formula O4Os
MDL Number MFCD00011150
Molecular Weight 254.23
MOL File 20816-12-0.mol

Chemical Properties

Description
Osmium is an extremely dense, blue-grey, hard but brittle metal that remains lustrous at high temperature as well. Osmium possesses quite remarkable chemical and physical properties. It has the highest melting point and the lowest vapour pressure in the platinum family. Osmium is highly volatile and extremely toxic and is rarely used in its pure state and often alloyed with other metals. Those alloys are utilised in high-wear applications. Osmium alloys such as osmiridium are very hard and, along with other platinum group metals, are used in the tips of fountain pens, instrument pivots, and electrical contacts, as they can resist wear from frequent operation. Osmium tetroxide is a colourless to pale yellow crystalline solid with an odour that has been described as pungent or chlorine-like. Osmium tetroxide is used as a tissue fixative for electron microscopy. Osmium tetroxide has been used in fingerprint detection and for staining fatty tissues for optical and electron microscopy studies.
Appearance Osmium is a blue-white metal. It is found in platinum ores and in the naturally occurring alloy osmiridium. Osmium when heated in air or when the finely divided form is exposed to air at room temperature, oxidizes to form the tetroxide (OsO4), osmic acid. Osmium tetraoxide is a colorless, crystalline solid or pale-yellow mass. Unpleasant, acrid, chlorine-like odor. A liquid above 41°C.
Melting point  40°C
Boiling point  130 °C
density  1.04
vapor density  8.8 (vs air)
vapor pressure  7 mmHg at 20 °C
Fp  -40 °C
storage temp.  Refrigerator
solubility  Soluble in alcohol, ether, chloroform, benzene, ammonium hydroxide, phosphorus oxychloride and carbon tetrachloride
form  Solution
color  White to yellow,or lemon yellow
Specific Gravity 5.10
Odor Acrid, chlorine-like odor detectable at 2 ppm (20 mg/m3)
Stability: Stable. Incompatible with strong acids, hydrogen chloride, organic materials, finely powdered metals.
Water Solubility  Soluble in chloroform, alcohol and ethers.Soluble in water, organic solvents, benzene, alcohol, ether, ammonium hydroxide, phosphorus oxychloride and carbon tetrachloride.
Sensitive  Air Sensitive
Merck  14,6893
CAS DataBase Reference 20816-12-0(CAS DataBase Reference)
NIST Chemistry Reference Osmium tetraoxide(20816-12-0)
EPA Substance Registry System 20816-12-0(EPA Substance)

Safety Data

Hazard Codes  O,T,C,T+,F,Xi,Xn
Risk Statements 
R8:Contact with combustible material may cause fire.
R23/24/25:Toxic by inhalation, in contact with skin and if swallowed .
R40:Limited evidence of a carcinogenic effect.
R34:Causes burns.
R26/27/28:Very Toxic by inhalation, in contact with skin and if swallowed .
R42/43:May cause sensitization by inhalation and skin contact .
R11:Highly Flammable.
R67:Vapors may cause drowsiness and dizziness.
R66:Repeated exposure may cause skin dryness or cracking.
R36/37/38:Irritating to eyes, respiratory system and skin .
R19:May form explosive peroxides.
Safety Statements 
S17:Keep away from combustible material .
S26:In case of contact with eyes, rinse immediately with plenty of water and seek medical advice .
S27:Take off immediately all contaminated clothing .
S36/37/39:Wear suitable protective clothing, gloves and eye/face protection .
S45:In case of accident or if you feel unwell, seek medical advice immediately (show label where possible) .
S7/9:Keep container tightly closed and in a well-ventilated place .
S36/37:Wear suitable protective clothing and gloves .
S16:Keep away from sources of ignition-No smoking .
S28:After contact with skin, wash immediately with plenty of ... (to be specified by the manufacturer) .
S23:Do not breathe gas/fumes/vapor/spray (appropriate wording to be specified by the manufacturer) .
RIDADR  UN 3175 4.1/PG 2
WGK Germany  3
RTECS  RN1140000
TSCA  Yes
HazardClass  6.1
PackingGroup  I
HS Code  28439090
Safety Profile
Poison by ingestion, inhalation, and intraperitoneal routes. Human systemic effects by inhalation: lachrymation and other eye effects and structural or functional changes in trachea or bronch. Experimental reproductive effects. Mutation data reported. Explodes on contact with 1 -methylimidazole. Catalytic decomposition of hydrogen peroxide can be hazardous. See also OSMIUM
Hazardous Substances Data 20816-12-0(Hazardous Substances Data)
Toxicity
LD50 oral (rat)
14 mg/kg
LCLO inhal (rat)
40 ppm (4 h)
PEL (OSHA)
0.0002 ppm (0.002 mg/m3)
TLV-TWA (ACGIH)
0.0002 ppm (0.002 mg/m3)
STEL (ACGIH)
0.0006 ppm (0.006 mg/m3)
IDLA 1 mg Os/m3

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