522. Ammonium Fluoride

Nomenclature

CAS number: 12125-01-8
Ammonium fluoride ((NH4)F); neutral ammonium fluoride.
FH4N; mol wt 37.04.
F 51.29%, H 10.88%, N 37.82%.
NH4F.

Description and references

Prepd by passing ammonia gas into ice-cooled 40% hydrofluoric acid or by heating 1 part NH4Cl with 2.25 parts NaF and separating the ammonium fluoride by sublimation: Kwasnik in Handbook of Preparative Inorganic Chemistry vol. 1, G. Brauer, Ed. (Academic Press, New York, 2nd ed., 1963) p 183. Review: Steele, “Ammonium Fluoride” in Mellor's vol. VIII, supplement I, Nitrogen (part 1), 370-377 (1964).

Properties

Deliquescent, hygroscopic leaflets or needles. Hexagonal prisms by sublimation. Occurs commercially as a granular powder. d 1.015. On heating dec into NH3 and HF. Poisonous, corrosive. Soly in water (0°): 100 g/100 ml. Decomposed by hot water into NH3 and ammonium bifluoride. (NH4F.HF). Cannot be obtained by evapn of its aq soln. Slightly sol in alcohol. The aq soln is acid. May be stored in iron vessels. Incompat. Quinine salts; soluble calcium salts.

Caution

Potential symptoms of overexposure by ingestion are nausea, salivation, vomiting, abdominal pain, diarrhea, hemorrhagic gastroenteritis, muscular weakness, tremors, convulsions, vascular collapse. Increased respiration is followed by depression, death. Chronic toxicity: Fluoride poisoning characterized by mottling of enamel, generalized osteosclerosis, calcification in tendons and ligaments; synostoses.

Use

Etching and frosting glass; extracting agent; as antiseptic in brewing beer; preserving wood; in printing and dyeing textiles; as mothproofing agent.