Ammonium fluoride
The ammonium cation
The fluoride anion
ball-and-stick model of an ammonium cation (left) and a fluoride anion (right)
Solid sample of ammonium fluoride
IUPAC name
Ammonium fluoride
Other names
Neutral ammonium fluoride
3D model (JSmol)
ECHA InfoCard 100.031.975 Edit this at Wikidata
EC Number
  • 235-185-9
RTECS number
  • BQ6300000
UN number 2505
  • InChI=1S/FH.H3N/h1H;1H3 checkY
  • InChI=1/FH.H3N/h1H;1H3
  • [F-].[NH4+]
Molar mass 37.037 g/mol
Appearance White crystalline solid
Density 1.009 g/cm3
Melting point 100 °C (212 °F; 373 K) (decomposes)
83.5 g/100 ml (25 °C) [1]
Solubility slightly soluble in alcohol, insoluble in liquid ammonia
-23.0·10−6 cm3/mol
Wurtzite structure (hexagonal)
GHS labelling:[2]
GHS05: Corrosive GHS06: Toxic
H301, H311, H314, H330, H331
P260, P261, P264, P270, P271, P280, P284, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P311, P312, P320, P321, P322, P330, P361, P363, P403+P233, P405, P501
NFPA 704 (fire diamond)
Flash point Non-flammable
Safety data sheet (SDS) ICSC 1223
Related compounds
Other anions
Ammonium chloride
Ammonium bromide
Ammonium iodide
Other cations
Sodium fluoride
Potassium fluoride
Related compounds
Ammonium bifluoride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ammonium fluoride is the inorganic compound with the formula NH4F. It crystallizes as small colourless prisms, having a sharp saline taste, and is highly soluble in water. Like all fluoride salts, it is moderately toxic in both acute and chronic overdose.[3]

Crystal structure

Ammonium fluoride adopts the wurtzite crystal structure, in which both the ammonium cations and the fluoride anions are stacked in ABABAB... layers, each being tetrahedrally surrounded by four of the other. There are N−H···F hydrogen bonds between the anions and cations.[4] This structure is very similar to ice, and ammonium fluoride is the only substance which can form mixed crystals with water.[5]


On passing hydrogen fluoride gas (in excess) through the salt, ammonium fluoride absorbs the gas to form the addition compound ammonium bifluoride. The reaction occurring is:

NH4F + HF → NH4HF2

It sublimes when heated—a property common among ammonium salts. In the sublimation, the salt decomposes to ammonia and hydrogen fluoride, and the two gases can recombine to give ammonium fluoride, i.e. the reaction is reversible:

[NH4]F ⇌ NH3 + HF


This substance is commonly called "commercial ammonium fluoride". The word "neutral" is sometimes added to "ammonium fluoride" to represent the neutral salt—[NH4]F vs. the "acid salt" (NH4HF2). The acid salt is usually used in preference to the neutral salt in the etching of glass and related silicates. This property is shared among all soluble fluorides. For this reason it cannot be handled in glass test tubes or apparatus during laboratory work.

It is also used for preserving wood, as a mothproofing agent, in printing and dying textiles, and as an antiseptic in breweries.[6]


  1. ^ "Ammonium Fluoride".
  2. ^ "Ammonium Fluoride".
  3. ^ "Fluoride Toxicity - an overview | ScienceDirect Topics". Retrieved 2020-12-16.
  4. ^ A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
  5. ^ Brill, R.; Zaromb, S. "Mixed Crystals of Ice and Ammonium Fluoride". Nature. 173 (4398): 316–317. doi:10.1038/173316a0.
  6. ^ Aigueperse, Jean; Paul Mollard; Didier Devilliers; Marius Chemla; Robert Faron; Renée Romano; Jean Pierre Cuer (2005). "Fluorine Compounds, Inorganic". In Ullmann (ed.). Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_307.