| Physical Description |
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. Density 8.2 lb / gal. 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. |
| Color/Form |
Colorless gas, fumes in air |
| Odor |
... Strong, irritating odor ... |
| Boiling Point |
67.1 °F at 760 mmHg (EPA, 1998) |
| Melting Point |
-118.4 °F (EPA, 1998) |
| Flash Point |
Not Flammable (EPA, 1998) |
| Solubility |
Miscible (NIOSH, 2023) |
| Density |
0.991 at 67.1 °F (EPA, 1998) - Less dense than water; will float |
| Vapor Density |
0.7 (EPA, 1998) - Lighter than air; will rise (Relative to Air) |
| Vapor Pressure |
400 mmHg at 36.5 °F (EPA, 1998) |
| Henry's Law Constant |
Henry's Law constant: 9.61 mol/L atm (1.04X10-4 cu m atm/mol) /Hydrofluoric acid/ |
| Stability/Shelf Life |
Stable under recommended storage conditions. |
| Autoignition Temperature |
Not flammable (USCG, 1999) |
| Decomposition |
When heated to decomp it emits highly corrosive fumes of /hydrogen fluoride/. |
| Corrosivity |
Corrosive, dissolves silica, silicic acid, glass |
| Heat of Vaporization |
7.493 kJ/mol at 101.3 kPa |
| pH |
In water a weak acid |
| Surface Tension |
Surface tension: 10.2 mN/m at 0 °C |
| Ionization Potential |
15.98 eV |
| Odor Threshold |
Odor Threshold Low: 0.04 [mmHg] Odor threshold from AIHA |
| Refractive Index |
Index of refraction, liquid: 1.1574 at 25 °C, 589.3 nm |
| Dissociation Constants |
pKa = 3.19 |
| Other Experimental Properties |
Anhydrous HF is one of the most acidic substances known; Hammett acidity function: -10.98; forms a constant boiling mixture with water; dissolves silica, silicic acid, glass; should be stored in steel cylinders. Many compounds are soluble in hydrogen fluoride |
| Chemical Classes |
Toxic Gases & Vapors -> Acids, Inorganic |
