Hydrogen fluoride is a colourless fuming liquid at room temperatures. With a boiling point of only 19.5°C, it readily forms a colourless vapour with an irritating odour that is typically detectable by smell at 0.04 ppm.
Hydrogen fluoride is extremely corrosive and poisonous. Both its liquid and vapour forms cause severe and painful burns upon contact with the skin, eyes and mucous membranes. If inhaled, HF vapour may cause pulmonary oedema which may not become apparent until 12-24 hours after exposure.
HF is used in the production of fluorocarbons (e.g. PTFE) and inorganic fluorides, metal refining (e.g. uranium), as a catalyst in the chemical industry and for etching glass and pottery.