Physical and Chemical Properties Physical state Anhydrous (100%) HF may be found in both liquid and gaseous states, depending on temperature. Aqueous mixtures (hydrofluoric acid) are liquid. Physical properties Table 2 - Physico-chemical properties of HF Reference and Property comments Boiling point 19.5 oC at 1013 hPa (OECD, 1999) (anhydrous): Melting - 83 oC (OECD, 1999) Relative density: 1.016 g/cm3 at 0 oC (liquid) (OECD, 1999) 0.901 g/cm3 at 22 oC (liquid) Vapour pressure: 1033 hPa at 200C (OECD, 1999) Partial vapour 70% 120 mm Hg (Dupont, 1984) pressure of aqueous 35% 2.5 mm Hg Values estimated solutions: 8 0.16 mm Hg from graphs. –10% solubility: Miscible in all proportions (OECD, 1999) Law Constant: 2.07 Pa.m3/mol at 200C Calculated value. Partition coefficient (OECD, 1999) - 1.4 (Log Kow): Flammability: Non-flammable (OECD, 1999) Explosive Non-explosive (OECD, 1999) properties: Oxidising Not oxidising (OECD, 1999) properties: threshold: 30 g/m3 (OECD, 1999) (This is not a reliable warning sign if levels are increased gradually.) Conversion factors: 1 mg/m3 = 1.22 ppm (101 kPa, (OECD, 1999) 25oC) 1 ppm = 0.82 mg/m3 (101 kPa, 25oC)
Physical and Chemical Properties Physical state Anhydrous (100%) HF may be found in both liquid and gaseous states, depending on temperature. Aqueous mixtures (hydrofluoric acid) are liquid. Physical properties Table 2 - Physico-chemical properties of HF Property Reference and comments Boiling point (anhydrous): 19.5 oC at 1013 hPa (OECD, 1999) Melting - 83 oC (OECD, 1999) Relative density: 1.016 g/cm3 at 0 oC (liquid) 0.901 g/cm3 at 22 oC (liquid) (OECD, 1999) Vapour pressure: 1033 hPa at 200C (OECD, 1999) Partial vapour pressure of aqueous solutions: 70% 120 mm Hg 35% 2.5 mm Hg 8 –10% 0.16 mm Hg (Dupont, 1984) Values estimated from graphs. solubility: Miscible in all proportions (OECD, 1999) Law Constant: 2.07 Pa.m3/mol at 200C Calculated value. Partition coefficient (Log Kow): - 1.4 (OECD, 1999) Flammability: Non-flammable (OECD, 1999) Explosive properties: Non-explosive (OECD, 1999) Oxidising properties: Not oxidising (OECD, 1999) threshold: 30 g/m3 (OECD, 1999) (This is not a reliable warning sign if levels are increased gradually.) Conversion factors: 1 mg/m3 = 1.22 ppm (101 kPa, 25oC) (OECD, 1999) 1 ppm = 0.82 mg/m3 (101 kPa, 25oC)