Fluoroantimonic acid is one of the strongest superacids known, with a Hammett acidity function of -21. It is a mixture of hydrogen fluoride and antimony pentafluoride.
| IUPAC Name | Fluoroantimony(V) acid |
| Molecular Formula | H[SbF6] |
| CAS Number | 16950-06-4 |
| Synonyms | Hydrogen hexafluoroantimonate(V), Antimony hexafluoride hydrate, Hydrogen antimony fluoride, Hydrofluoric acid with pentafluoroantimony (1:1) |
| InChI | InChI=1S/F6Sb.H/h1H;/q+1;/p-1 |
Fluoroantimonic Acid pH
Fluoroantimonic acid is a superacid and has a pH value of less than -14. This is because the pH scale measures the concentration of hydrogen ions (H+) in a solution, and superacids have higher concentrations of H+ ions than pure water.
Traditional pH meters cannot accurately measure the pH of fluoroantimonic acid, as they are not designed to handle such strong acids. Instead, scientists use the Hammett acidity function to measure the acidity of fluoroantimonic acid. The Hammett acidity function compares the acidity of superacids by using the degree of protonation of a reference compound. Fluoroantimonic acid has a Hammett acidity function of -21, which is the most negative value possible and indicates that it is one of the strongest known superacids.
Fluoroantimonic Acid Structure:
Fluoroantimonic acid has a molecular structure that consists of a hydrogen ion (H+) and a hexafluoroantimonate(V) ion ([SbF6]^-). The SbF6 ion acts as a Lewis acid, while the H+ ion acts as a Bronsted acid. The compound is highly polar due to the electronegativity difference between the hydrogen and fluorine atoms. The bond between antimony and fluoride is covalent, while the bond between hydrogen and fluoride is polar covalent.
Fluoroantimonic Acid molar mass:
Fluoroantimonic acid has a molar mass of 216.74 g/mol. It is a highly reactive and corrosive superacid composed of hydrogen fluoride (HF) and antimony pentafluoride (SbF5). The high molar mass of fluoroantimonic acid can be attributed to the presence of the heavy antimony atom in its molecular structure.
Fluoroantimonic Acid boiling point:
HSbF6 is a highly reactive and unstable compound and thus does not have a defined boiling point. It decomposes at temperatures above -10°C, releasing toxic fumes of hydrogen fluoride gas. Its boiling point is estimated to be around 20-30°C, but it is not a useful parameter for describing the properties of HSbF6.
Fluoroantimonic Acid melting point:
HSbF6 does not have a well-defined melting point due to its highly reactive nature. It can only exist in the liquid state and decomposes rapidly upon cooling to lower temperatures. It is estimated to decompose around -90°C, releasing toxic fumes of hydrogen fluoride and antimony pentafluoride.
Fluoroantimonic Acid density g/ml:
The density of HSbF6 is 2.1 g/mL. This high density can be attributed to the presence of heavy antimony atom in its molecular structure. It is a highly corrosive and reactive compound and should be handled with extreme care. The density of HSbF6 also makes it difficult to handle in laboratories.
Fluoroantimonic Acid molecular weight:
The molecular weight of fluoroantimonic acid is 236.76 g/mol. It is composed of one hydrogen ion, one antimony ion, and six fluoride ions. The high molecular weight of fluoroantimonic acid can be attributed to the presence of the heavy antimony atom in its molecular structure.
Fluoroantimonic Acid formula:
The chemical formula of fluoroantimonic acid is H[SbF6]. It is composed of one hydrogen ion (H+) and one hexafluoroantimonate(V) ion ([SbF6]^-). The [SbF6]^- ion is formed by the reaction of antimony pentafluoride (SbF5) with hydrogen fluoride (HF). The formula represents the simplest whole number ratio of atoms present in the compound.
| Appearance | Colorless to pale yellow liquid |
| Specific Gravity | 2.1 g/mL |
| Color | Colorless to pale yellow |
| Odor | Odorless |
| Molar Mass | 236.76 g/mol |
| Density | 2.1 g/mL |
| Melting Point | Decomposes around -90°C |
| Boiling Point | Decomposes above -10°C |
| Flash Point | Not applicable |
| Water Solubility | Reacts violently with water |
| Solubility | Soluble in anhydrous HF, SbF5, SO2F2, and SO2ClF |
| Vapour Pressure | Not applicable |
| Vapour Density | Not applicable |
| PKa | -21 (Hammett acidity function) |
| pH | Less than -14 |
Note: Fluoroantimonic acid is a highly reactive and corrosive compound that should be handled with extreme care. Its physical and chemical properties are difficult to measure accurately due to its unstable nature and the limited methods available for handling it. The values listed in this table are estimates based on available literature and may not be precise.
Fluoroantimonic Acid Safety and Hazards
Fluoroantimonic acid is an extremely dangerous and highly corrosive substance that poses significant health and safety hazards. It is a strong oxidizing agent and can react violently with water, organic compounds, and even some metals. It can cause severe burns and tissue damage upon contact with skin or eyes, and inhalation of its vapors can lead to respiratory distress and lung damage.
Trained personnel must handle fluoroantimonic acid using specialized equipment and protective clothing in well-ventilated and properly equipped laboratories. Regulatory agencies strictly regulate and restrict the use of fluoroantimonic acid due to its potential to cause severe injury and environmental damage.
| Hazard Symbols | Corrosive |
| Safety Description | Do not breathe vapors. Wear protective gloves, clothing, and eye/face protection. Avoid contact with skin, eyes, and clothing. Use only in a chemical fume hood. |
| UN IDs | UN3264 |
| HS Code | 28111990 |
| Hazard Class | 8 (Corrosive substances) |
| Packing Group | III |
| Toxicity | Highly toxic and corrosive; can cause severe burns and tissue damage upon contact with skin or eyes, and inhalation of its vapors can lead to respiratory distress and lung damage. |
Fluoroantimonic Acid Synthesis Methods
Fluoroantimonic acid (HSbF6) is typically synthesized by mixing hydrogen fluoride (HF) and antimony pentafluoride (SbF5) in a 1:1 molar ratio. The reaction takes place under anhydrous conditions and at low temperatures to prevent the decomposition of the resulting superacid. The overall reaction can be represented as follows:
HF + SbF5 → HSbF6
The reaction is highly exothermic and can release a large amount of heat. Therefore, it is typically carried out in a well-ventilated and controlled environment, such as a chemical fume hood, using appropriate protective measures.
To prepare HSbF6, one can react antimony trifluoride (SbF3) with HF in the presence of an oxidizing agent like SbF5 or sulfur dioxide difluoride (SO2F2). This reaction requires anhydrous conditions and low temperatures. The reaction can be expressed as follows:
SbF3 + 3 HF + SO2F2 → HSbF6 + SO2
HSbF6 is a highly reactive and unstable compound that requires special handling and storage. It is typically stored in sealed and air-tight containers under anhydrous conditions and at low temperatures to prevent decomposition. Proper safety measures and protective equipment are essential when working with HSbF6 due to its high toxicity and corrosiveness.
Fluoroantimonic Acid Uses
Fluoroantimonic acid (HSbF6) is one of the strongest known superacids and has a wide range of industrial and research applications. Here are some of the uses of fluoroantimonic acid:
- HSbF6 serves as a catalyst in various chemical reactions, including alkylations, isomerizations, and polymerizations.
- The petrochemical industry uses HSbF6 in the production of high-octane gasoline and other hydrocarbons.
- Researchers in the pharmaceutical industry employ HSbF6 as a catalyst in synthesizing various pharmaceuticals, including antiviral and anticancer drugs.
- HSbF6 finds application in the etching and cleaning of electronic components, such as microchips and semiconductors, used in the production of electronic components.
- Scientists utilize HSbF6 as a research tool in various fields of chemistry and material science, including the synthesis of novel materials and the study of chemical reactions.
HSbF6 is a highly reactive and dangerous substance that requires specialized handling and protective measures. It is strictly regulated and should only be used by trained personnel in well-equipped laboratories. The potential hazards associated with HSbF6 limit its use to specialized applications where no other alternatives are available.
Questions:
Can fluoroantimonic acid dissolve diamond?
HSbF6 can dissolve diamond due to its strong acidic properties. Trained professionals in well-equipped laboratories with proper safety measures and protective equipment can carry out the highly dangerous reaction between diamond and HSbF6. However, it is not a practical or cost-effective method for diamond processing or cutting. Mechanical cutting or laser cutting are much more commonly used due to their efficiency and safety.
Where to buy fluoroantimonic acid?
Buying HSbF6 is extremely difficult due to its highly dangerous and regulated nature. Only licensed and authorized companies or institutions possessing the necessary permits and equipment can handle and store the acid safely.
The Chemical Weapons Convention (CWC) and the United States Chemical Facility Anti-Terrorism Standards (CFATS) regulations classify HSbF6 as a hazardous and controlled substance.
Government agencies such as the Environmental Protection Agency (EPA), the Department of Homeland Security (DHS), and the Bureau of Industry and Security (BIS) strictly regulate and control the sale and purchase of HSbF6.
If you have a legitimate need for HSbF6, you can contact licensed chemical suppliers or research institutions with the necessary permits and expertise.
However, you must provide a detailed justification and obtain the necessary approvals and permits before making any purchase.