Ammonium fluoride

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
Names
	IUPAC name Ammonium fluoride
	Other names Neutral ammonium fluoride
Identifiers
CAS Number	12125-01-8 ;
3D model (JSmol)	Interactive image ;
ChEBI	CHEBI:66871 ;
ChemSpider	23806 ;
ECHA InfoCard	100.031.975
EC Number	235-185-9;
PubChem CID	25516 ;
RTECS number	BQ6300000;
UNII	4QT928IM0A ;
UN number	2505
CompTox Dashboard (EPA)	DTXSID6050463 ;
	InChI InChI=1S/FH.H3N/h1H;1H3 Key: LDDQLRUQCUTJBB-UHFFFAOYSA-N ; InChI=1/FH.H3N/h1H;1H3 Key: LDDQLRUQCUTJBB-UHFFFAOYAM;
	SMILES [F-].[NH4+];
Properties
Chemical formula	NH4F
Molar mass	37.037 g/mol
Appearance	White crystalline solid ; hygroscopic
Density	1.009 g/cm3
Melting point	100 °C (212 °F; 373 K) (decomposes)
Solubility in water	83.5 g/100 ml (25 °C)
Solubility	slightly soluble in alcohol, insoluble in liquid ammonia
Magnetic susceptibility (χ)	−23.0×10−6 cm3/mol
Structure
Crystal structure	Wurtzite structure (hexagonal)
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H314, H330, H331
Precautionary statements	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)	3 0 0
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). verify (what is ?) Infobox references

Last updated January 24, 2025

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.^{[ citation needed ]}

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.^[3] This structure is very similar to ice, and ammonium fluoride is the only substance which can form mixed crystals with water.^[4]

Reactions

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

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

[NH₄]F ⇌ NH₃ + HF

Uses

This substance is commonly called "commercial ammonium fluoride". The word "neutral" is sometimes added to "ammonium fluoride" to represent the neutral salt [NH₄]F as opposed to 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.

Ammonium fluoride is a critical component of buffered oxide etch (BOE), a wet etchant used in microfabrication. It acts as the buffering agent in a solution of concentrated HF, creating an etchant with a more controllable rate of etching (than that of simple concentrated HF solutions).^[5]

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

Related Research Articles

<span class="mw-page-title-main">Ammonium hydrosulfide</span> Chemical compound

Ammonium hydrosulfide is the chemical compound with the formula [NH₄]SH.

Selenic acid is the inorganic compound with the formula H₂SeO₄. It is an oxoacid of selenium, and its structure is more accurately described as O₂Se(OH)₂. It is a colorless compound. Although it has few uses, one of its salts, sodium selenate is used in the production of glass and animal feeds.

Potassium cyanate is an inorganic compound with the formula KOCN. It is a colourless solid. It is used to prepare many other compounds including useful herbicide. Worldwide production of the potassium and sodium salts was 20,000 tons in 2006.

Hexafluorosilicic acid is an inorganic compound with the chemical formula H^₂SiF^₆. Aqueous solutions of hexafluorosilicic acid consist of salts of the cation and hexafluorosilicate anion. These salts and their aqueous solutions are colorless.

Ammonium bifluoride is an inorganic compound with the formula [NH₄][HF₂] or [NH₄]F·HF. It is produced from ammonia and hydrogen fluoride. This colourless salt is a glass-etchant and an intermediate in a once-contemplated route to hydrofluoric acid.

<span class="mw-page-title-main">Zinc fluoride</span> Chemical compound

Zinc fluoride is an inorganic chemical compound with the chemical formula ZnF₂. It is encountered as the anhydrous form and also as the tetrahydrate, ZnF₂·4H₂O (rhombohedral crystal structure). It has a high melting point and has the rutile structure containing 6 coordinate zinc, which suggests appreciable ionic character in its chemical bonding. Unlike the other zinc halides, ZnCl₂, ZnBr₂ and ZnI₂, it is not very soluble in water.

Tetramethylammonium hydroxide (TMAH or TMAOH) is a quaternary ammonium salt with molecular formula N(CH₃)₄⁺ OH⁻. It is commonly encountered in form of concentrated solutions in water or methanol. TMAH in solid state and its aqueous solutions are all colorless, but may be yellowish if impure. Although TMAH has virtually no odor when pure, samples often have a strong fishy smell due to presence of trimethylamine which is a common impurity. TMAH has several diverse industrial and research applications.

Tantalum(V) fluoride is the inorganic compound with the formula TaF₅. It is one of the principal molecular compounds of tantalum. Characteristic of some other pentafluorides, the compound is volatile but exists as an oligomer in the solid state.

The bifluoride ion is an inorganic anion with the chemical formula [HF₂]⁻. The anion is colorless. Salts of bifluoride are commonly encountered in the reactions of fluoride salts with hydrofluoric acid. The commercial production of fluorine involves electrolysis of bifluoride salts.

Ammonium ferric citrate has the formula [NH₄]y[Fe_x(C₆H₄O₇)]. The iron in this compound is trivalent. All three carboxyl groups and the central hydroxyl group of citric acid are deprotonated. A distinguishing feature of this compound is that it is very soluble in water, in contrast to ferric citrate which is not very soluble.

<span class="mw-page-title-main">Titanium tetrafluoride</span> Chemical compound

Titanium(IV) fluoride is the inorganic compound with the formula TiF₄. It is a white hygroscopic solid. In contrast to the other tetrahalides of titanium, it adopts a polymeric structure. In common with the other tetrahalides, TiF₄ is a strong Lewis acid.

<span class="mw-page-title-main">Hexafluorophosphate</span> Anion with the chemical formula PF6–

Hexafluorophosphate is an anion with chemical formula of [PF₆]⁻. It is an octahedral species that imparts no color to its salts. [PF₆]⁻ is isoelectronic with sulfur hexafluoride, SF₆, and the hexafluorosilicate dianion, [SiF₆]²⁻, and hexafluoroantimonate [SbF₆]⁻. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.

<span class="mw-page-title-main">Potassium hexafluorophosphate</span> Chemical compound

Potassium hexafluorophosphate is a chemical compound with the formula KPF₆. This colourless salt consists of potassium cations and hexafluorophosphate anions. It is prepared from phosphorus pentachloride:

Buffered oxide etch (BOE), also known as buffered HF or BHF, is a wet etchant used in microfabrication. It is a mixture of a buffering agent, such as ammonium fluoride NH₄F, and hydrofluoric acid (HF). Its primary use is in etching thin films of silicon nitride (Si₃N₄) or silicon dioxide (SiO₂), by the reaction:

Arsenic trifluoride is a chemical compound of arsenic and fluorine with the chemical formula AsF₃. It is a colorless liquid which reacts readily with water. Like other inorganic arsenic compounds, it is highly toxic.

Ammonium hexafluorophosphate is the inorganic compound with the formula NH₄PF₆. It is a white water-soluble, hygroscopic solid. The compound is a salt consisting of the ammonium cation and hexafluorophosphate anion. It is commonly used as a source of the hexafluorophosphate anion, a weakly coordinating anion. It is prepared by combining neat ammonium fluoride and phosphorus pentachloride. Alternatively it can also be produced from phosphonitrilic chloride:

<span class="mw-page-title-main">Potassium bifluoride</span> Chemical compound

Potassium bifluoride is the inorganic compound with the formula K[HF₂]. This colourless salt consists of the potassium cation and the bifluoride anion. The salt is used as an etchant for glass. Sodium bifluoride is related and is also of commercial use as an etchant as well as in cleaning products.

<span class="mw-page-title-main">Ammonium hexafluorotitanate</span> Chemical compound

Ammonium hexafluorotitanate is the inorganic compound with the chemical formula (NH₄)₂[TiF₆]. A colorless salt, the compound consists of ammonium ions and the hexafluorotitanate dianion.

<span class="mw-page-title-main">Potassium heptafluoroniobate</span> Chemical compound

Potassium heptafluoroniobate is the inorganic compound with the formula K₂NbF₇. A white water-soluble salt, it is one of the more important fluorides of niobium. It is often invoked as an intermediate in the separation of niobium from tantalum. These two elements are generally found together in ores and their separation presents a challenge since they form very similar compounds. The basis of their separation hinges on the stability and solubility of the fluorides and oxyfluorides. Reduction of this salt gives niobium metal.

References

↑ "Ammonium Fluoride". pubchem.ncbi.nlm.nih.gov.
↑ "Ammonium Fluoride". pubchem.ncbi.nlm.nih.gov.
↑ A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.
↑ Brill, R.; Zaromb, S. (1954). "Mixed Crystals of Ice and Ammonium Fluoride". Nature. 173 (4398): 316–317. Bibcode:1954Natur.173..316B. doi:10.1038/173316a0. S2CID 4146351.
↑ Wolf, Stanley; Tauber, Richard (1986). Silicon Processing for the VLSI Era: Volume 1 - Process Technology. pp. 532–533. ISBN 978-0-9616721-3-3.
↑ 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. ISBN 3-527-30673-0.

This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.

[1] "Ammonium Fluoride". pubchem.ncbi.nlm.nih.gov.

[2] "Ammonium Fluoride". pubchem.ncbi.nlm.nih.gov.

[3] A. F. Wells, Structural Inorganic Chemistry, 5th ed., Oxford University Press, Oxford, UK, 1984.

[4] Brill, R.; Zaromb, S. (1954). "Mixed Crystals of Ice and Ammonium Fluoride". Nature. 173 (4398): 316–317. Bibcode:1954Natur.173..316B. doi:10.1038/173316a0. S2CID 4146351.

[Wolf-5] Wolf, Stanley; Tauber, Richard (1986). Silicon Processing for the VLSI Era: Volume 1 - Process Technology. pp. 532–533. ISBN 978-0-9616721-3-3.

[Aigueperse-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. ISBN 3-527-30673-0.

[1]

[2]

[3]

[4]

[5]

[6]