Hexafluorosilicic acid
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| Dihydrogen hexafluorosilicate | |
|---|---|
| IUPAC name | Dihydrogen hexafluorosilicate |
| Other names | Hexafluorosilicic acid fluorosilicic acid fluosilicic acid |
| Identifiers | |
| CAS number | |
| RTECS number | VV8225000 |
| Properties | |
| Molecular formula | H2F6Si |
| Molar mass | 144.0922 g/mol |
| Appearance | colourless solution |
| Density | 1.22 g/cm3 25% aqueous soln |
| Structure | |
| Molecular shape | Octahedral SiF62− |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | Toxic, corrosive. |
| R-phrases | R20, R21, R22, R34, |
| S-phrases | S26, S27 |
| Flash point | Non-flammable. |
| Related Compounds | |
| Related compounds | HF HPF6 HBF4 |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references | |
Hexafluorosilicic acid is the chemical compound with the formula H2SiF6. The species is encountered only as an aqueous solution. Evaporation of aqueous H2SiF6 results in loss of HF and SiF4.
H2SiF6 is a by-product from the reaction of fluoroapatite with sulfuric acid, which produces HF, which in turn reacts with silicate minerals:
- SiO2 + 6 HF → H2SiF6 + 2 H2O
Aqueous solutions of H2SiF6 contain the hexafluorosilicate anion, SiF62−. In this octahedral anion, the Si-F bond distances are 1.71 Å.[1]
Uses
H2SiF6 is commonly used for water fluoridation in the United States.
H2SiF6 is a reagent in organic synthesis for cleaving Si-O bonds of silyl ethers. It is more reactive for this purpose than HF. It reacts faster with t-butyldimethysilyl (TBDMS) ethers than triisopropylsilyl (TIPS) ethers.[1]
Hexafluorosilicic acid and the salts are sused as wood preservation agent. The aluminium and magnesium hexafluorosilicate are two used compounds. [1]
Safety
Hexafluorosilicic acid releases hydrogen fluoride when evaporated, so it has similar risks. It is corrosive and may cause fluoride poisoning; inhalation of the vapors may cause lung edema. Like hydrogen fluoride, it attacks glass and stoneware.[1]
References
Template:Inorganic-compound-stub
de:Hexafluorokieselsäure it:Acido fluorosilicico
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
