Difference between revisions of "Hydrogen fluoride"
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| Formula = HF | | Formula = HF | ||
| HenryConstant = | | HenryConstant = | ||
| − | | LogP = | + | | LogP = 0.23 |
| − | | MolarMass = | + | | MolarMass = 20.01 g/mol |
| MeltingPt = | | MeltingPt = | ||
| MeltingPtC = −83.6 | | MeltingPtC = −83.6 | ||
| MeltingPt_ref = | | MeltingPt_ref = | ||
| MeltingPt_notes = | | MeltingPt_notes = | ||
| + | | Odor = Pungent | ||
| pKa = 3.17 | | pKa = 3.17 | ||
| pKb = | | pKb = | ||
| Solubility = Miscible | | Solubility = Miscible | ||
| − | | SolubleOther = Reacts with amines<br>Slightly soluble in [[diethyl ether]], [[trifluoroacetic acid]]<br>Poorly soluble in [[benzene]], [[tetralin]], [[toluene]], [[xylene]] | + | | SolubleOther = Reacts with amines, bases<br>Slightly soluble in [[diethyl ether]], [[trifluoroacetic acid]]<br>Poorly soluble in [[benzene]], [[tetralin]], [[toluene]], [[xylene]] |
| Solvent = | | Solvent = | ||
| VaporPressure = 783 mmHg (20 °C) | | VaporPressure = 783 mmHg (20 °C) | ||
| Line 81: | Line 82: | ||
}} | }} | ||
| Section5 = {{Chembox Explosive | | Section5 = {{Chembox Explosive | ||
| − | | ShockSens = | + | | ShockSens = Non-explosive |
| − | | FrictionSens = | + | | FrictionSens = Non-explosive |
| − | | DetonationV = | + | | DetonationV = Non-explosive |
| − | | REFactor = | + | | REFactor = Non-explosive |
}} | }} | ||
| Section6 = {{Chembox Hazards | | Section6 = {{Chembox Hazards | ||
| − | | AutoignitionPt = | + | | AutoignitionPt = Non-flammable |
| − | | ExploLimits = | + | | ExploLimits = Non-explosive |
| ExternalMSDS = [https://www.mathesongas.com/pdfs/msds/MAT11170.pdf Matheson] | | ExternalMSDS = [https://www.mathesongas.com/pdfs/msds/MAT11170.pdf Matheson] | ||
| − | | FlashPt = | + | | FlashPt = Non-flammable |
| LD50 = | | LD50 = | ||
| − | | LC50 = | + | | LC50 = 1,276 ppm (rat, 1 hr)<br>1,774 ppm (monkey, 1 hr)<br>4,327 ppm (guinea pig, 15 min) |
| MainHazards = Highly corrosive<br>Highly toxic | | MainHazards = Highly corrosive<br>Highly toxic | ||
| NFPA-F = | | NFPA-F = | ||
| Line 104: | Line 105: | ||
| OtherFunction = | | OtherFunction = | ||
| OtherFunction_label = | | OtherFunction_label = | ||
| − | | OtherCompounds = [[Hydrogen chloride]] | + | | OtherCompounds = [[Hydrogen chloride]]<br>[[Hydrogen bromide]]<br>[[Hydrogen iodide]] |
}} | }} | ||
}} | }} | ||
| Line 113: | Line 114: | ||
Hydrogen fluoride will react with most common materials in the presence of moisture, including glass, forming silicon tetrafluoride and hexafluorosilicic acid. | Hydrogen fluoride will react with most common materials in the presence of moisture, including glass, forming silicon tetrafluoride and hexafluorosilicic acid. | ||
| − | Hydrogen fluoride reacts with metals to form a thin layer of metal fluoride on their surface, which protects the metal from further corrosion. If the layer is broken, HF will corrode the metal beneath. The resulting passivation is used to protect metal tanks used to store compressed HF. | + | Hydrogen fluoride reacts with metals to form a thin layer of metal fluoride on their surface, which protects the metal from further corrosion. If the layer is broken, HF will corrode the metal beneath. The resulting passivation is used to protect metal tanks used to store compressed HF gas. |
===Physical=== | ===Physical=== | ||
| Line 124: | Line 125: | ||
==Preparation== | ==Preparation== | ||
| − | While hydrofluoric acid is somewhat safer to handle as it does not volatilize easily, hydrogen fluoride boils at near room temperature, which makes preparation, handling and storage extremely difficult and dangerous. Since it reacts with glass, lab glassware is inadequate and the installation for the production of HF must be made from certain plastics, like PTFE, or passivated carbon steel or other metals, such as [[nickel]], [[copper]] or [[lead]]. Synthesizing and storing hydrogen fluoride is | + | While hydrofluoric acid is somewhat safer to handle as it does not volatilize easily, hydrogen fluoride boils at near room temperature, which makes preparation, handling and storage extremely difficult and dangerous. Since it reacts with glass, lab glassware is inadequate and the installation for the production of HF must be made from certain plastics, like PTFE, or passivated carbon steel or other metals, such as [[nickel]], [[copper]] or [[lead]]. Synthesizing and storing anhydrous hydrogen fluoride in a home setting is expensive, dangerous and may not be worth the risk. |
| − | The industrial route involves refluxing concentrated sulfuric acid (90-98%) with [[calcium fluoride]] or [[sodium fluoride]] between 100-300 °C, in a PTFE or PTFE clad reactor. The HF gas evolution is slow and endothermic, which means that stopping the heating stops the gas evolution, which keeps the dangerous HF inside the vessel in the event of an accident. The resulting HF gas is condensed and collected in a chilled container or cooled and injected in a passivated metal cylinder. One SM user managed to perform this process | + | The industrial route involves refluxing concentrated sulfuric acid (90-98%) with [[calcium fluoride]] or [[sodium fluoride]] between 100-300 °C, in a PTFE or PTFE clad reactor. The HF gas evolution is slow and endothermic, which means that stopping the heating stops the gas evolution, which keeps the dangerous HF inside the vessel in the event of an accident. The resulting HF gas is condensed and collected in a chilled container or cooled and injected in a passivated metal cylinder. One SM user managed to perform this process on a small scale, and obtained a small amount, by heating the mixture at 200°C.<ref>http://www.sciencemadness.org/talk/viewthread.php?tid=9842</ref> |
Since producing elemental [[fluorine]] is next to impossible in a home setup, the H<sub>2</sub> + F<sub>2</sub> route is not viable. | Since producing elemental [[fluorine]] is next to impossible in a home setup, the H<sub>2</sub> + F<sub>2</sub> route is not viable. | ||
==Projects== | ==Projects== | ||
| + | *Make hydrofluoric acid | ||
*Alkylation catalyst | *Alkylation catalyst | ||
*Acyl fluorides | *Acyl fluorides | ||
| Line 139: | Line 141: | ||
===Storage=== | ===Storage=== | ||
| − | Anhydrous hydrogen fluoride is almost always stored in passivated compressed metal tanks. Since it will slowly react with the metal of the tank, hydrogen pressure will build up inside the tank, which may lead to explosion, if the tank is severely corroded. Check the tank periodically for any pressure build-up or leaks<ref>http://www.ehs.ucsb.edu/files/docs/ls/HF_lecturebottle.pdf</ref> | + | Anhydrous hydrogen fluoride is almost always stored in passivated compressed metal tanks. Since it will slowly react with the metal of the tank, hydrogen pressure will build up inside the tank, which may lead to an explosion, if the tank is severely corroded. Check the tank periodically for any pressure build-up or leaks<ref>http://www.ehs.ucsb.edu/files/docs/ls/HF_lecturebottle.pdf</ref> |
While HF's boiling point is close to that of room temperature and you might be tempted to think that simply keeping it in a bottle in a very cold place, like a freezer, would be good enough, '''it should NEVER be stored in the freezer''', as it will give off highly toxic and corrosive fumes even when cold. | While HF's boiling point is close to that of room temperature and you might be tempted to think that simply keeping it in a bottle in a very cold place, like a freezer, would be good enough, '''it should NEVER be stored in the freezer''', as it will give off highly toxic and corrosive fumes even when cold. | ||
===Disposal=== | ===Disposal=== | ||
| − | Hydrogen fluoride can be neutralized in liquid form by reacting it with calcium | + | Hydrogen fluoride can be neutralized in liquid form by reacting it with soluble calcium compounds to form the insoluble [[calcium fluoride]], which is safe to handle, in either a well ventilated area or in a special cabinet, to reduce the amount of HF being aerosolized. In gaseous form, excess ammonia can be used to neutralize it to ammonium fluoride, though this will cause a very fine mist of NH<sub>4</sub>F to form in air. Since ammonium fluoride can slowly hydrolyze back into HF in the presence of moisture, further treatment with calcium hydroxide will convert it to the more stable calcium fluoride, which can be safely removed and discarded. |
==References== | ==References== | ||
| Line 166: | Line 168: | ||
[[Category:Contact poisons]] | [[Category:Contact poisons]] | ||
[[Category:Irritants]] | [[Category:Irritants]] | ||
| + | [[Category:Liquids]] | ||
Latest revision as of 23:09, 24 October 2021
| Names | |
|---|---|
| IUPAC name
Hydrogen fluoride
| |
| Other names
Anhydrous hydrofluoric acid
| |
| Properties | |
| HF | |
| Molar mass | 20.01 g/mol |
| Appearance | Colorless fuming liquid (<19.5 °C) Colorless gas (STP) |
| Odor | Pungent |
| Density | 1.15 g/L, gas (25 °C) 0.99 g/cm3, liquid (19.5 °C) |
| Melting point | −83.6 °C (−118.5 °F; 189.6 K) |
| Boiling point | 19.5 °C (67.1 °F; 292.6 K) |
| Miscible | |
| Solubility | Reacts with amines, bases Slightly soluble in diethyl ether, trifluoroacetic acid Poorly soluble in benzene, tetralin, toluene, xylene |
| Vapor pressure | 783 mmHg (20 °C) |
| Acidity (pKa) | 3.17 |
| Thermochemistry | |
| Std molar
entropy (S |
8.687 J·g-1·K-1 (gas) |
| Std enthalpy of
formation (ΔfH |
−13.66 kJ/g (gas) −14.99 kJ/g (liquid) |
| Hazards | |
| Safety data sheet | Matheson |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
| LC50 (Median concentration)
|
1,276 ppm (rat, 1 hr) 1,774 ppm (monkey, 1 hr) 4,327 ppm (guinea pig, 15 min) |
| Related compounds | |
| Related compounds
|
Hydrogen chloride Hydrogen bromide Hydrogen iodide |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Hydrogen fluoride is highly dangerous chemical compound with the chemical formula HF, the anhydride of hydrofluoric acid. Unlike the other hydrogen halides, HF has a high boiling point, of 19.5 °C, due to the strong intermolecular hydrogen bonds between the hydrogen and fluorine atoms.
Contents
Properties
Chemical
Hydrogen fluoride will react with most common materials in the presence of moisture, including glass, forming silicon tetrafluoride and hexafluorosilicic acid.
Hydrogen fluoride reacts with metals to form a thin layer of metal fluoride on their surface, which protects the metal from further corrosion. If the layer is broken, HF will corrode the metal beneath. The resulting passivation is used to protect metal tanks used to store compressed HF gas.
Physical
Hydrogen fluoride is a fuming colorless liquid that boils at near-room temperature, giving off a colorless gas, with a strong, pungent acid smell, highly corrosive and toxic. It is miscible with water.
Availability
Anhydrous hydrogen fluoride is sold by various chemical companies, but due to its great hazards, only industrial or authorized entities can purchase it.
Hydrogen fluoride is more readily available in aqueous solution as hydrofluoric acid.
Preparation
While hydrofluoric acid is somewhat safer to handle as it does not volatilize easily, hydrogen fluoride boils at near room temperature, which makes preparation, handling and storage extremely difficult and dangerous. Since it reacts with glass, lab glassware is inadequate and the installation for the production of HF must be made from certain plastics, like PTFE, or passivated carbon steel or other metals, such as nickel, copper or lead. Synthesizing and storing anhydrous hydrogen fluoride in a home setting is expensive, dangerous and may not be worth the risk.
The industrial route involves refluxing concentrated sulfuric acid (90-98%) with calcium fluoride or sodium fluoride between 100-300 °C, in a PTFE or PTFE clad reactor. The HF gas evolution is slow and endothermic, which means that stopping the heating stops the gas evolution, which keeps the dangerous HF inside the vessel in the event of an accident. The resulting HF gas is condensed and collected in a chilled container or cooled and injected in a passivated metal cylinder. One SM user managed to perform this process on a small scale, and obtained a small amount, by heating the mixture at 200°C.[1]
Since producing elemental fluorine is next to impossible in a home setup, the H2 + F2 route is not viable.
Projects
- Make hydrofluoric acid
- Alkylation catalyst
- Acyl fluorides
Handling
Safety
Hydrogen fluoride is extremely corrosive and toxic. Contact with skin or tissues will lead to necrosis and even death.
Storage
Anhydrous hydrogen fluoride is almost always stored in passivated compressed metal tanks. Since it will slowly react with the metal of the tank, hydrogen pressure will build up inside the tank, which may lead to an explosion, if the tank is severely corroded. Check the tank periodically for any pressure build-up or leaks[2]
While HF's boiling point is close to that of room temperature and you might be tempted to think that simply keeping it in a bottle in a very cold place, like a freezer, would be good enough, it should NEVER be stored in the freezer, as it will give off highly toxic and corrosive fumes even when cold.
Disposal
Hydrogen fluoride can be neutralized in liquid form by reacting it with soluble calcium compounds to form the insoluble calcium fluoride, which is safe to handle, in either a well ventilated area or in a special cabinet, to reduce the amount of HF being aerosolized. In gaseous form, excess ammonia can be used to neutralize it to ammonium fluoride, though this will cause a very fine mist of NH4F to form in air. Since ammonium fluoride can slowly hydrolyze back into HF in the presence of moisture, further treatment with calcium hydroxide will convert it to the more stable calcium fluoride, which can be safely removed and discarded.
References
- ↑ http://www.sciencemadness.org/talk/viewthread.php?tid=9842
- ↑ http://www.ehs.ucsb.edu/files/docs/ls/HF_lecturebottle.pdf
Relevant Sciencemadness threads
- Articles containing unverified chemical infoboxes
- Chembox articles without image
- Chemical compounds
- Inorganic compounds
- Hydrogen compounds
- Fluorine compounds
- Fluorides
- Materials unstable in basic solution
- Corrosive chemicals
- Chemicals that attack glassware
- Things that can kill you very quickly
- Blood agents
- Choking agents
- Cytotoxic agents
- Contact poisons
- Irritants
- Liquids
