Osmium tetroxide

  • Osmic acid anhydride
  • Osmium oxide
Formula OsO4
Description Colorless crystalline solid or pale-yellow mass with an unpleasant acrid chlorine-like odor.
Uses Catalyzes chlorate, peroxide, periodate & other oxidn.

Registry Numbers and Inventories.
CAS 20816-12-0
EC (EINECS/ELINCS) 244-058-7
EC Index Number 076-001-00-5
EC Class Very toxic; Corrosive
EC Risk Phrase R 26/27/28 34
EC Safety Phrase S 7/9 26 45
RTECS RN1140000
RTECS class Drug; Mutagen; Reproductive Effector; Human Data
UN (DOT) 2471
Merck 12,7024
Beilstein/Gmelin 2527 (G)
Swiss Giftliste 1 G-2676
US TSCA Listed
Austrailia AICS Listed
New Zealand Listed
Korea ECL Listed

Odor Threshold Odor threshold 0.0019 ppm
Formula O4Os
Formula mass 254.20
Melting point, C 40
Boiling point, C 130
Vapor pressure, mmHg 0.78 (0 C)
Vapor density (air=1) 8.8
Saturation Concentration 9212 ppm (0.9%) at 20 C (calculated)
Critical temperature 405
Critical pressure 17
Density 1.04 g/cm3
Solubility in water 60 g/L
Surface tension 49.8 erg/cm2 (50 C)
Dielectric constant 1.003
Heat of fusion 14.3 kJ/mol
Heat of vaporization 36.4 kJ/mol

Hazards and Protection.
Storage Keep away from heat, sparks, and flame. Keep away from sources of ignition. Do not store near combustible materials. Store in a tightly closed container. Store in a cool, dry, well-ventilated area away from incompatible substances. Poison room locked.
Handling Wash thoroughly after handling. Remove contaminated clothing and wash before reuse. Use with adequate ventilation. Minimize dust generation and accumulation. Empty containers retain product residue, (liquid and/or vapor), and can be dangerous. Keep container tightly closed. Avoid contact with heat, sparks and flame. Do not get on skin or in eyes. Do not ingest or inhale. Do not pressurize, cut, weld, braze, solder, drill, grind, or expose empty containers to heat, sparks or open flames.
Protection Eyes: Wear appropriate protective eyeglasses or chemical safety goggles as described by OSHA's eye and face protection regulations in 29 CFR 1910.133 or European Standard EN166. Skin: Wear appropriate protective gloves to prevent skin exposure. Clothing: Wear appropriate protective clothing to prevent skin exposure.
Respirators A respiratory protection program that meets OSHA's 29 CFR 1910.134 and ANSI Z88.2 requirements or European Standard EN 149 must be followed whenever workplace conditions warrant a respirator's use.
Small spills/leaks Reduce airborne dust and prevent scattering by moistening with water. Wear a self contained breathing apparatus and appropriate Personal protection. (See Exposure Controls, Personal Protection section). Sweep up, then place into a suitable container for disposal. Avoid generating dusty conditions. Remove all sources of ignition.
Disposal code 27
Stability Stable under normal temperatures and pressures.
Incompatibilities Strong oxidizing agents, hydrochloric acid, bases, finely powdered metals, organic materials, strong reducing agents.
Decomposition Carbon monoxide, irritating and toxic fumes and gases, carbon dioxide.

Flash Point,C 4
Fire fighting Extinguish fire using agent suitable for type of surrounding fire. (Material itself does not burn or burns with difficulty.) Use water in flooding quantities as fog. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Solid streams of water may spread fire.
Fire potential Not combustible.
Hazards Some are oxidizers and may ignite combustibles (wood, paper, oil, clothing, etc.). Contact with metals may evolve flammable hydrogen gas. Containers may explode when heated.
Combustion products Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes.
NFPA Health 3
  Flammability 3  
  Reactivity 0  

Exposure limit(s) OSHA PEL: TWA 0.002 mg/m3 NIOSH REL: TWA 0.002 mg/m3 (0.0002 ppm) ST 0.006 mg/m3 (0.0006 ppm) NIOSH IDLH: 1 mg/m3 (as Os)
Poison_Class 1
Exposure effects Prolonged or repeated skin contact may cause dermatitis. Prolonged or repeated exposure may cause adverse reproductive effects.
   Ingestion May be fatal if swallowed. Aspiration hazard. Causes cough, sore throat, chest pain, and lightheadedness. May cause nausea, vomiting, abdominal pain, and increased salivation.
   Inhalation May cause severe irritation of the respiratory tract with sore throat, coughing, shortness of breath and delayed lung edema. May cause bronchopneumonia and possible death. Olfactory fatigue may occur. Can produce delayed pulmonary edema.
   Skin May cause skin irritation and possible burns. Causes skin irritation and possible burns.
   Eyes Causes severe eye irritation. Causes eye burns. May cause blindness. May cause lacrimation (tearing), blurred vision, and photophobia. May cause chemical conjunctivitis and corneal damage.

First aid
   Ingestion Do NOT induce vomiting. If victim is conscious and alert, give 2-4 cupfuls of milk or water. Get medical aid immediately.
   Inhalation Get medical aid immediately. Remove from exposure to fresh air immediately. If not breathing, give artificial respiration. If breathing is difficult, give oxygen.
   Skin Get medical aid immediately. Immediately flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes.
   Eyes Immediately flush eyes with plenty of water for at least 15 minutes, occasionally lifting the upper and lower eyelids. Get medical aid immediately.

UN number 2471
Response guide 154
Hazard class 6.1
Packing Group I  
HS Code 2843 90 90  
Std. Transport # 4923150