- Hydrosilicofluoric acid
- Fluosilicic acid
- Silicofluoric acid
- Hydrogen hexafluorosilicate
Colorless to straw yellow liquid with a slightly acrid odor.
Agent in water fluoridation, in preliminary treatment of hides & skins, & to reduce reflectivity in glass surfaces, disinfectant for copper and brass vessels, impregnating ingredient to preserve wood & to harden masonary, chemical intermediate for aluminum trifluoride, cryolite, & fluorsilicates, electroplating agent for chromium.
Registry Numbers and Inventories.
EC Index Number
S 26 27 45
Swiss Giftliste 1
Japan ENCS (MITI)
Melting point, °C
Solubility in water
Hazards and Protection.
The more concnsolution (but not anhydrous liq) can be stored in glass, although some etching will take place around the surface. Usually stored in iron containers.
All chemicals should be considered hazardous. Avoid direct physical contact. Use appropriate, approved safety equipment. Untrained individuals should not handle this chemical or its container. Handling should occur in a chemical fume hood.
Workers handling dangerous substances should be supplied with eye and face protection, resp protective equipment, protective clothing and foot and leg protection. Additional protection may be provided by use of lanolin as barrier cream.
Wear positive pressure self-contained breathing apparatus (SCBA).
Neutralizing Agents for Acids and Caustics: Lime.
Fumes in air dihydrate fumes in air 60.97% Solution.
Can react with strong acids (such as sulfuric acid) to release fumes of toxic hydrogen fluoride Attacks glass and materials containing silica Reacts exothermically with chemical bases (examples: amines, amides, inorganic hydroxides) Reacts with active metals, including iron and aluminum to dissolve the metal and liberate hydrogen and/or toxic gases Reacts with cyanide salts and compounds to release gaseous hydrogen cyanide.
Dangerous when heated to decomposition, emits highly toxic and corrosive fumes of fluorides.
Fire Extinguishing Agents Not to Be Used: Avoid direct contact between water and acid.Fire Extinguishing Agents: Use dry chemical, carbon dioxide or water spray on adjacent fires.
Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes.
Contact with metals may evolve flammable hydrogen gas.
Irritating fumes of hydrogen fluoride may form in fire.
TLV (as F): ppm; 2.5 mg/m3 (as TWA) (ACGIH 1995-1996).
Hyperactive reflexes, painful muscle spasms, weakness and tetanic contractures may be noted due to fluoride induced hypocalcemia. Prenatal fluoride supplementation (2.2 mg NaF or 1 mg fluoride daily) during the last two trimesters of pregnancy has been reported to be safe.
Epigastric pain, nausea, dysphagia, salivation, hematemesis, and diarrhea may be noted. These effects may be delayed for several hours following exposure. Gi symptoms are noted when 3 to 5 mg/kg of fluoride are ingested.
Respirations are first stimulated then depressed. Death is usually from respiratory paralysis. Following inhalation, coughing and choking may be noted.
Urticaria and pruritus have been reported following exposure to fluoride.
Give large amounts of water; do NOT induce vomiting.
Remove to fresh air. If breathing is difficult, give oxygen.
Remove contaminated clothing and shoes. Flush with water.
Immediately wash with water for 15 min.; call a physician.