Boron trifluoride Boron trifluoride is a colourless, pungent-smelling gas. It is harmful when inhaled. It is soluble in water and is slowly hydrolyzed by cold water to produce corrosive hydrofluoric acid. It has heavier vapours than air. Exposure of the containers to fire or heat for an extended period of time may result in theirWhy BF3 acts as Lewis Acid | Boron trifluoride