Physical And Chemical Properties The pH of a 5% aqueous solution of Ammonium Bifluoride is 3.5. In aqueous solution it releases 0.35 pounds of hydrofluoric acid per pound of Ammonium Bifluoride. In strong acid solutions, Ammonium Bifluoride releases 0.70 pounds of hydrofluoric acid per pound. Since the product absorbs heat when aqueous solutions are prepared, it is often advisable to use warm water. Additional properties are listed below. Melting Point: 258 F (126 C) Boiling Point: 462 F (239 C) Specific Gravity: 1.5 Solubility in Water (25C): 41.5% by weight Sales Specification Content(NH4HF2): 98.0% min (NH4)2SiF6: 2.0% max Loss on drying: 1.0% max Residue on ignition: 0.2% max Sulfate (based on SO4): 0.1% max Packing 50 LB Bag, 44 bags per pallet DOT Transportation UN Number.: 1727 Proper Shipping Name: Ammonium Bifluoride, Solid Hazard Class: 8 Packing Group: II