AMMONIUM FLUORIDE
Formula : NH4F; MW 31.04 
Synonyms : neutral ammonium fluoride; normal ammonium fluoride
Uses
is used for etching glass; for preserving wood; as a mothproofing agent; in printing and dyeing textiles; and as an antiseptic in brewery
Physical Properties
White, deliquescent, crystalline solid; occurs in various forms, as granular powder (commercial products), needles or leaflets, or hexagonal prism (formed on sublimation and condensation); density 1.009 g/cm³ at 25°C; decomposes on heating; highly soluble in cold water (100g/100g at 0°C); decomposes in hot water; slightly soluble in alcohol, insoluble in liquid ammonia
Thermochemical Properties
Preparation
is made by passing ammonia gas through a 40% aqueous solution of hydrofluoric acid (ice-cooled):
Alternatively, it may be prepared by heating ammonium chloride with excess sodium fluoride. Ammonium fluoride is obtained by sublimation.
Also, it may be prepared by mixing an equimolar amount of aqueous ammonia and ammonium bifluoride.
Reactions
Decomposes on heating to ammonia and hydrogen fluoride; also decomposes in hot water producing ammonia and ammonium bifluoride:
The solution is acidic; it reacts with weak bases forming double salts; i.e., ammonium hexafluoroaluminate, 
ammonium hexafluorophosphate, 
ammonium hexafluorosilicate, 
ammonium hexafluorogallate, 
Chemical Analysis
Elemental composition : F 51.30%, H 10.88%, N 37.82%. A measured amount is dissolved in water and the aqueous solution diluted appropriately and analyzed for fluoride by fluoride ion-selective electrode, or by ion chromatography. Ammonium ion (or liberated ammonia) is analyzed by titration or by ammonium ion-specific electrode (see Ammonia).
Toxicity
is a highly toxic substance; ingestion can cause nausea, vomiting, abdominal pain, tremor, hemorrhage, muscular weakness, convulsions and vascular collapse. Ingestion of large quantity can cause death. Chronic effects include mottling of enamel, osteoclerosis and calcification in ligaments.
Tags: AMMONIUM FLUORIDE, NH4F; MW 31.04
