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FLUOROSILICIC ACIDICSC: 1233
Hexafluorosilicic acid
Dihydrogen hexafluorosilicate
Fluosilicic acid
Hydrosilicofluoric acid
October 2004
CAS #: 16961-83-4
UN #: 1778
EC Number: 241-034-8

  ACUTE HAZARDS PREVENTION FIRE FIGHTING
FIRE & EXPLOSION Not combustible. Gives off irritating or toxic fumes (or gases) in a fire.        In case of fire in the surroundings, use appropriate extinguishing media.   

 AVOID ALL CONTACT! IN ALL CASES CONSULT A DOCTOR! 
  SYMPTOMS PREVENTION FIRST AID
Inhalation Burning sensation. Cough. Laboured breathing. Shortness of breath. Symptoms may be delayed. See Notes.  Use ventilation, local exhaust or breathing protection.  Fresh air, rest. Half-upright position. Refer for medical attention. 
Skin Redness. Pain. Skin burns.  Protective gloves. Protective clothing.  Remove contaminated clothes. Rinse skin with plenty of water or shower. Refer immediately for medical attention. 
Eyes Redness. Pain. Severe deep burns.  Wear face shield or eye protection in combination with breathing protection.  First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention. 
Ingestion Burning sensation. Abdominal cramps. Vomiting. Shock or collapse.  Do not eat, drink, or smoke during work.  Rinse mouth. Do NOT induce vomiting. Give one or two glasses of water to drink. Refer for medical attention . 

SPILLAGE DISPOSAL CLASSIFICATION & LABELLING
Personal protection: complete protective clothing including self-contained breathing apparatus. Collect leaking and spilled liquid in sealable iron containers as far as possible. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations. Do NOT let this chemical enter the environment. 

According to UN GHS Criteria

 

Transportation
UN Classification
UN Hazard Class: 8; UN Pack Group: II 

STORAGE
Separated from strong bases and food and feedstuffs. Well closed. 
PACKAGING
Unbreakable packaging.
Put breakable packaging into closed unbreakable container.
Do not transport with food and feedstuffs. 
FLUOROSILICIC ACID ICSC: 1233
PHYSICAL & CHEMICAL INFORMATION

Physical State; Appearance
FUMING COLOURLESS LIQUID WITH PUNGENT ODOUR. 

Physical dangers
 

Chemical dangers
Decomposes on heating. This produces toxic fumes including hydrogen fluoride. The solution in water is a strong acid. It reacts violently with bases and is corrosive. Reacts with water and steam. This produces toxic and corrosive fumes. Attacks glass and stoneware. Attacks many metals. This produces flammable/explosive gas (hydrogen - see ICSC 0001). This substance (anhydrous form) dissociates almost instantly into silicon tetrafluoride and corrosive and toxic hydrogen fluoride. 

Formula: F6H2Si / H2SiF6
Molecular mass: 144.1
Decomposes
Melting point: see Notes
Relative density (water = 1): see Notes
Solubility in water: miscible
Vapour pressure: see Notes 


EXPOSURE & HEALTH EFFECTS

Routes of exposure
The substance can be absorbed into the body by inhalation of its aerosol and by ingestion. 

Effects of short-term exposure
The substance is corrosive to the eyes, skin and respiratory tract. Corrosive on ingestion. Inhalation of the vapour may cause lung oedema. The effects may be delayed. Medical observation is indicated. See Notes. 

Inhalation risk
No indication can be given about the rate at which a harmful concentration of this substance in the air is reached on evaporation at 20°C. 

Effects of long-term or repeated exposure
The substance may have effects on the bones and teeth. This may result in fluorosis. 


OCCUPATIONAL EXPOSURE LIMITS
 

ENVIRONMENT
This substance may be hazardous to the environment. Special attention should be given to aquatic organisms. 

NOTES
Marketed only as aqueous solution.
Solidification point for 60-70% solution: solidifies at about 19°C, forming a crystalline dihydrate.
Melting point for 35% solution: <-30°C.
Relative density for a 61% solution is 1.46 and for 35% solution is 1.38.
Vapour pressure for a 35% solution is about 3 kPa.
The symptoms of lung oedema often do not become manifest until a few hours have passed and they are aggravated by physical effort. Rest and medical observation are therefore essential.
Temperature of decomposition is unknown in the literature.
Immediate administration of an appropriate inhalation therapy by a doctor, or by an authorized person, should be considered. 

ADDITIONAL INFORMATION
  EC Classification
Symbol: C; R: 34; S: (1/2)-26-27-45; Note: B 

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    See Also:
       Toxicological Abbreviations