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| Names | |||
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| IUPAC name Ammonium fluoride | |||
| Other names Neutral ammonium fluoride | |||
| Identifiers | |||
3D model (JSmol) | |||
| ChEBI | |||
| ChemSpider |
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| ECHA InfoCard | 100.031.975 | ||
| EC Number |
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| RTECS number |
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| UNII | |||
| UN number | 2505 | ||
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| Properties | |||
| 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) | ||
| 83.5 g/100 ml (25 °C)[1] | |||
| Solubility | slightly soluble in alcohol, insoluble in liquid ammonia | ||
| −23.0×10−6 cm3/mol | |||
| Structure | |||
| Wurtzite structure (hexagonal) | |||
| Hazards | |||
| GHS labelling:[2] | |||
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| Danger | |||
| 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 | |||
Otheranions | Ammonium chloride Ammonium bromide Ammonium iodide | ||
Othercations | Sodium fluoride Potassium fluoride | ||
Related compounds | Ammonium bifluoride | ||
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |||
Ammonium fluoride is theinorganic 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]
Ammonium fluoride adopts thewurtzite 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···Fhydrogen bonds between the anions and cations.[3] This structure is very similar toice, and ammonium fluoride is the only substance which can form mixed crystals with water.[4]
On passinghydrogen fluoride gas (in excess) through the salt, ammonium fluoride absorbs the gas to form theaddition compoundammonium bifluoride. The reaction occurring is:
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:
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 theetching of glass and relatedsilicates. 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 ofbuffered oxide etch (BOE), a wetetchant used inmicrofabrication. It acts as thebuffering agent in a solution of concentratedHF, 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 dyeingtextiles, and as anantiseptic inbreweries.[6]
