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Hydrofluoric acid

Athanor · official

FH · 20.0064 g/mol

IUPAC name: fluorane

Also called hydrogen fluoride, HF

Open in Athanor
The structure of Hydrofluoric acid
Drawn from its SMILES with RDKit
CorrosiveAcute toxicityDangerFatal if swallowed · Fatal in contact with skin · Causes severe skin burns and eye damage · Fatal if inhaled

Names and identifiers

IUPAC name
fluorane
Synonyms
hydrogen fluoride, HF, Hydrogen fluoride
+ 36 more

Fluorhydric acid, Hydrofluoride, Rubigine, Fluorwasserstoff, Antisal 2B, Hydrofluoricum acidum, Fluorowodor, Fluorwaterstof, Acido fluoridrico, Acide fluorhydrique, RCRA waste number U134, fluoridohydrogen, RGL5YE86CZ, DTXSID1049641, CHEBI:29228, fluoric acid, NSC-750679, Fluohydric Acid, Acid, Fluohydric, Acid, Fluorhydric, Acid, Hydrofluoric, Fluoride, Hydrogen, Anhydrous hydrogen fluoride, Acidum Fluoricum, RefChem:6444, Aqueous hydrogen fluoride, Hydrofluoric acid, anhydrous, DTXCID8029600, 231-634-8, fluorane, Hydrogen-fluoride, Hydrogen fluoride, anhydrous, MFCD00011346, [2H]hydrogen fluoride, Fluorowodor [Polish], Caswell No. 484

Molecular formula
FH
Empirical formula
FH
Molecular weight
20.0064 g/mol
Exact mass
20.00623
CAS number
7664-39-3
PubChem CID
14917
Canonical SMILES
F
Isomeric SMILES
F
InChI
InChI=1S/FH/h1H
InChIKey
KRHYYFGTRYWZRS-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Physical properties

TemperaturePressureDensity
Appearance
Hydrofluoric acid, solution appears as a colorless fuming mobile aqueous solution with a pungent odor. Corrosive to metals and tissue. Highly toxic by ingestion and inhalation. Exposure to fumes or very short contact with liquid may cause severe painful burns; penetrates skin to cause deep-seated ulceration that may lead to gangrene.[1]
8 values

From CAMEO Chemicals, the most authoritative source here.

ValueAs writtenSource
–shownHydrofluoric acid, solution appears as a colorless fuming mobile aqueous solution with a pungent odor. Corrosive to metals and tissue. Highly toxic by ingestion and inhalation. Exposure to fumes or very short contact with liquid may cause severe painful burns; penetrates skin to cause deep-seated ulceration that may lead to gangrene.[1] CAMEO Chemicals
–Hydrogen fluoride, anhydrous appears as a colorless fuming liquid boiling at 67 °F. Shipped as a liquid confined under its own vapor pressure. Corrosive to metals and tissue. Very short contact with fumes or small quantities of the liquid can cause severe, painful burns. Vapors are heavier than air. Used as a catalyst and raw material in chemical manufacture. Rate of onset: Immediate & Delayed Persistence: Minutes to hours Odor threshold: 0.4 ppm Source/use/other hazard: Aluminum and other metal industries; insecticide manufacturing-corrosive liq.[1] CAMEO Chemicals
–Gas Vapor; Wet Solid; CBI; Liquid[2] EPA Chemical Data Reporting (CDR)
–COLOURLESS GAS OR COLOURLESS FUMING LIQUID WITH PUNGENT ODOUR.[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–COLOURLESS FUMING LIQUID WITH PUNGENT ODOUR.[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–Colorless gas or fuming liquid (below 67 °F) with a strong, irritating odor.[4] Occupational Safety and Health Administration (OSHA)
–Colorless gas or fuming liquid (below 67 °F) with a strong, irritating odor. [Note: Shipped in cylinders.][5] The National Institute for Occupational Safety and Health (NIOSH)
–Hydrogen fluoride is a colorless fuming liquid below 67°F (19.4°C), or a colorless gas. When hydrogen fluoride is combined with water it is known as hydrofluoric acid, a colorless liquid, which in low concentrations is visually indistinguishable from water. Hydrofluoric acid that is more than 40% hydrogen fluoride fumes in air.[5] The National Institute for Occupational Safety and Health (NIOSH)
Odor
... Strong, irritating odor ...[6]
Melting point
-83.36 °C[7]
6 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
−69.0 °C-92.2 °F for 70% solution (ICSC, 2024)[1] CAMEO Chemicals
−83.6 °C-118.4 °F (EPA, 1998)[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
−83 °C-83 °C[3] ILO-WHO International Chemical Safety Cards (ICSCs)
−83 °C-118 °F[4] Occupational Safety and Health Administration (OSHA)
−83.4 °Cshown-83.36 °C[7] PAC Chemical Database, U.S. Department of Energy
−83 °C-118 °F[5] The National Institute for Occupational Safety and Health (NIOSH)

1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.

Boiling point
19.5 °C (67.1 °F) at 760 mmHg (EPA, 1998)[1]
6 values

5 of 5 sources agree on it (most common value).

ValueAs writtenSource
67 °C152 °F at 760 mmHg for 70% solution (ICSC, 2024)[1] CAMEO Chemicals
19.5 °Cshown67.1 °F at 760 mmHg (EPA, 1998)[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
20 °C20 °C[3] ILO-WHO International Chemical Safety Cards (ICSCs)
19 °C67 °F[4] Occupational Safety and Health Administration (OSHA)
20 °C20 °C @760 [mm Hg][7] PAC Chemical Database, U.S. Department of Energy
19 °C67 °F[5] The National Institute for Occupational Safety and Health (NIOSH)

1 more value was reported but failed the checks (unreadable or out of range), so it is not shown.

Density
0.991 at 19.5 °C (67.1 °F) (EPA, 1998) - Less dense than water[1]
8 values

4 of 5 sources agree on it (most common value).

ValueAs writtenSource
–1.23 for 70% solution (ICSC, 2024) - Denser than water[1] CAMEO Chemicals
–shown0.991 at 67.1 °F (EPA, 1998) - Less dense than water[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
–Relative density (water = 1): 1.0 (liquid at 4 °C)[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–Relative density (water = 1): 1.23[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–1[4] Occupational Safety and Health Administration (OSHA)
–0.818 @25 °C[7] PAC Chemical Database, U.S. Department of Energy
–1.00 (Liquid at 67 °F)[5] The National Institute for Occupational Safety and Health (NIOSH)
–0.69(relative gas density)[5] The National Institute for Occupational Safety and Health (NIOSH)

14 more values were reported but failed the checks (unreadable or out of range), so they are not shown.

Solubility in water
Solubility in water: miscible[3]
7 values

From ILO-WHO International Chemical Safety Cards (ICSCs), the most authoritative source here.

ValueAs writtenSource
–Miscible (ICSC, 2024)[1] CAMEO Chemicals
–Miscible (NIOSH, 2024)[1] CAMEO Chemicals
–Miscible with water[6] Hazardous Substances Data Bank (HSDB)cites Woodard AS; Fluorine Compounds. Inorganic. Hydrogen Flouride. Kirk-Othmer Encyclopedia of Chemical Technology. 1st ed., Volumes 1-15. New York, NY: Interscience Encyclopedia, 1960.
–Very soluble in water[6] Hazardous Substances Data Bank (HSDB)cites Larranaga, M.D., Lewis, R.J. Sr., Lewis, R.A.; Hawley's Condensed Chemical Dictionary 16th Edition. John Wiley & Sons, Inc. Hoboken, NJ 2016., p. 734
–Solubility in water: very good[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–shownSolubility in water: miscible[3] ILO-WHO International Chemical Safety Cards (ICSCs)
–Miscible[5] The National Institute for Occupational Safety and Health (NIOSH)
log P
0.23 (estimated)[3]
Vapor pressure
917 mmHg at 25 °C[6]
5 values

2 of 4 sources agree on it (most common value).

ValueAs writtenSource
150 mmHg150 mmHg at 77 °F (partial pressure for 70% solution) (ICSC, 2024)[1] CAMEO Chemicals
400 mmHg400 mmHg at 36.5 °F (EPA, 1998)[1] CAMEO Chemicalscites U.S. Environmental Protection Agency. 1998. Extremely Hazardous Substances (EHS) Chemical Profiles and Emergency First Aid Guides. Washington, D.C.: U.S. Government Printing Office.
917 mmHgshown917 mm Hg at 25 °C[6] Hazardous Substances Data Bank (HSDB)cites Daubert, T.E., R.P. Danner. Physical and Thermodynamic Properties of Pure Chemicals Data Compilation. Washington, D.C.: Taylor and Francis, 1989.
920 mmHgVapor pressure, kPa at 25 °C: 122[3] ILO-WHO International Chemical Safety Cards (ICSCs)
750 mmHg750 [mm Hg] @19.2 °C[7] PAC Chemical Database, U.S. Department of Energy

2 more values were reported but failed the checks (unreadable or out of range), so they are not shown.

Flash point
Reported, but no value passed the checks.
The value and why
  • Not Flammable (EPA, 1998) (could not be read; source [1])
Autoignition temperature
Reported, but no value passed the checks.
The 2 values and why
  • Not flammable (USCG, 1999) (could not be read; source [1])
  • Not flammable (USCG, 1999) (could not be read; source [1])
Refractive index
Reported, but no value passed the checks.
The value and why
  • Index of refraction, liquid: 1.1574 at 25 °C, 589.3 nm (could not be read; source [6])

Each value as its source reports it, with the source's number after it (listed under References). Where several sources report a property, the row shows the value most of them agree on, the rule the app uses; open the values to see every one.

Calculated

Heavy atoms
1
Rings
0
Aromatic rings
0
Fraction sp³ carbons (Fsp3)
0
H-bond donors
0 computed here · PubChem 1
H-bond acceptors
0 computed here · PubChem 1
Rotatable bonds
0
TPSA (Ų)
0
Formal charge
0
XLogP3
0.6 PubChem
Complexity
0 PubChem
Stereocenters
None
Double-bond geometry
None specified
Point group
C∞v of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • H5.04%
  • F94.96%

Isotope pattern

100%20.006

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
0.15 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-0.06 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
6.64 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 20.01
  • log P ≤ 5 (Crippen): 0.15
  • H-bond donors ≤ 5: 0
  • H-bond acceptors ≤ 10: 0

Passes all four rules.

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

Danger

Harmonized EU classification (CLP Annex VI). Source [8].

  • Corrosive
  • Acute toxicity
  • H300Fatal if swallowed
  • H310Fatal in contact with skin
  • H314Causes severe skin burns and eye damage
  • H330Fatal if inhaled

Precautionary statements: P260, P262, P264, P270, P271, P280, P284, P301+P316, P301+P330+P331, P302+P352, P302+P361+P354, P304+P340, P305+P354+P338, P316, P320, P321, P330, P361+P364, P363, P403+P233, P405, P501

View all classifications (5)
  • [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH300, H310, H314, H330
  • [8] Regulation (EC) No 1272/2008 of the European Parliament and of the Council · DangerH300, H310, H314, H330
  • [9] European Chemicals Agency (ECHA)This chemical does not meet GHS hazard criteria for < 0.1% (1 of 1001) of reports.
  • [9] European Chemicals Agency (ECHA) · 1,001 reports · DangerH300, H310, H318, H330
  • [6] Hazardous Substances Data Bank (HSDB) · DangerH300, H310, H314, H318, H330

Exposure limits

  • PEL-TWA (8-Hour Time Weighted Average): 3 ppm (2 mg/m³)[4]
  • PEL: TWA 3 ppm See Appendix G[5]
  • REL-C (Ceiling): 6 ppm (5 mg/m³) [15 minutes][4]
  • REL: TWA 3 ppm (2.5 mg/m3) C 6 ppm (5 mg/m3) [15-minute][5]
  • TLV: (as F): 0.5 ppm as TWA; 2 ppm as STEL; (skin); BEI issued.[3]
  • TLV-TWA (Time Weighted Average): 0.5 ppm [2004][4]

First aid

  • Excerpt from ERG Guide 157 [Substances - Toxic and/or Corrosive (Non-Combustible / Water-Sensitive)]: Refer to the "General First Aid" section. Specific First Aid: For corrosives, in case of contact, immediately flush skin or eyes with running water for at least 30 minutes. Additional flushing may be required. In case of skin contact with Hydrofluoric acid (UN1790), if calcium gluconate gel is available, rinse 5 minutes, then apply gel. Otherwise, continue rinsing until medical treatment is available. (ERG, 2024)[1]
  • Warning: Hydrogen fluoride is highly corrosive. Effects may be delayed from 1 to 24 hours. Caution is advised. Signs and Symptoms of Acute Hydrogen Fluoride Exposure: Acute exposure to hydrogen fluoride will result in irritation, burns, ulcerous lesions, and necrosis of the eyes, skin, and mucous membranes. Total destruction of the eyes is possible.[1]
  • General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]
  • General First Aid: · Call 911 or emergency medical service. · Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination. · Move victim to fresh air if it can be done safely. · Administer oxygen if breathing is difficult. · If victim is not breathing: -- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance. -- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped…[10]

Storage

  • Cool. Well closed. Fireproof if in building. Ventilation along the floor. Separated from food and feedstuffs and incompatible materials. Store in an area without drain or sewer access. See Chemical Dangers.[3]
  • Store only in original container. Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Cool. Ventilation along the floor. Store in an area without drain or sewer access.[3]
  • Hydrogen fluoride should be stored in cool, dry, well ventilated areas out of the direct rays of the sun.[6]
  • Keep container tightly closed in a dry and well-ventilated place. Containers which are opened must be carefully resealed and kept upright to prevent leakage. Store in corrosive resistant polyethylene container with a resistant inner liner. Do not store in glass Storage class (TRGS 510): Non-combustible, acute toxic Cat. 1 and 2 / very toxic hazardous materials[6]

Incompatibilities

  • Metals, water or steam. [Note: Corrosive to metals. Will attack glass and concrete].[6]
  • Interaction of the solid (bismuthic acid) with 40% hydrofluoric acid is violent, ozonized oxygen being evolved.[6]
  • Polymerization of cyanogen fluoride is rapid at ambient temp and explosive in presence of hydrogen fluoride.[6]
  • A chemical polishing soln consisting of nitric acid and hydrofluoric acid (1 vol each) and glycerol (2 vols) generated enough pressure during storage for 4 hr to rupture the closed plastics container. This was caused by gas evolution from oxidation of glycerol by the strongly oxidizing mixture. A mixture of nitric acid (80 mL), hydrofluoric acid (80 mL) and glycerol (240 mL) was used immediately for etching metal, again the next day, and then stored in a stoppered flask. After some 2-3 days, the stopper was ejected and approx 300 mL was sprayed around the fume cupboard containing the flask.[6]

Safety data sheets on the supplier’s page: Sigma-Aldrich, MP Biomedicals, LGC Standards.

Always read the supplier’s safety data sheet before working with it.

Spectra

Experimental spectra held by these sources; each link opens the source's own record.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. [1]CAMEO Chemicals · Public domain (NOAA) · via PubChem · retrieved 2026-10-14
  2. [2]EPA Chemical Data Reporting (CDR) · Public domain (US EPA) · via PubChem · retrieved 2026-10-14
  3. [3]ILO-WHO International Chemical Safety Cards (ICSCs) · CC BY 4.0 · via PubChem · retrieved 2026-10-14
  4. [4]Occupational Safety and Health Administration (OSHA) · Public domain (US DOL) · via PubChem · retrieved 2026-10-14
  5. [5]The National Institute for Occupational Safety and Health (NIOSH) · Public domain (US CDC) · via PubChem · retrieved 2026-10-14
  6. [6]Hazardous Substances Data Bank (HSDB) · Public domain (US NLM) · via PubChem · retrieved 2026-10-14
  7. [7]PAC Chemical Database, U.S. Department of Energy · Public domain (US DOE) · via PubChem · retrieved 2026-10-14
  8. [8]Regulation (EC) No 1272/2008 of the European Parliament and of the Council · EU reuse policy, CC BY 4.0 · via PubChem · retrieved 2026-10-14
  9. [9]European Chemicals Agency (ECHA) · ECHA legal notice: reuse with acknowledgement · via PubChem · retrieved 2026-10-14
  10. [10]Emergency Response Guidebook (ERG) · Public domain (US DOT) · via PubChem · retrieved 2026-10-14
  11. [11]SpectraBase · Linked only · via PubChem · retrieved 2026-10-14
  12. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  13. ·Literature on PubChem

Data last updated 2026-10-14.