Potassium hydrogen difluoride

Structural formula
General
Surname	Potassium hydrogen difluoride
other names	Potassium bifluoride; Potassium difluoride; acidic potassium fluoride; Matt salt;
Molecular formula	KHF 2
Brief description	colorless, hygroscopic solid with a slightly acidic odor
External identifiers / databases
EC number	232-156-2
ECHA InfoCard	100.029.233
PubChem	11829350
ChemSpider	21241938
Wikidata	Q419900
properties
Molar mass	78.11 g mol −1
Physical state	firmly
density	2.37 g cm −3
Melting point	239.5 ° C (decomposition)
solubility	good in water at (276 g l −1 at 20 ° C)
safety instructions
H and P phrases	H: 301-314
	P: 280-301 + 310 + 330-303 + 361 + 353-304 + 340 + 310-305 + 351 + 338
MAK	1 mg m −3
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Potassium hydrogen difluoride is a potassium salt of hydrofluoric acid , i.e. a chemical compound from the group of fluorides . It can be viewed as an addition compound of potassium fluoride and hydrogen fluoride (KF · HF).

Appearance and properties

Potassium hydrogen difluoride crystallizes from solutions of potassium fluoride with excess hydrofluoric acid, but can also be obtained from the reaction of potassium hydroxide or potassium carbonate solution with hydrofluoric acid. When heated above 400 ° C, the hydrogen difluoride decomposes again into fluoride and hydrogen fluoride.

Presentation:

{\ displaystyle \ mathrm {KF \ + \ HF \ \ longrightarrow \ KHF_ {2}}}

{\ displaystyle \ mathrm {KOH \ +2 \ HF \ \ longrightarrow \ KHF_ {2} + H_ {2} O}}

Decomposition by heating:

{\ displaystyle \ mathrm {KHF_ {2} \ {\ xrightarrow {\ Delta T}} \ KF \ + \ HF \ uparrow}}

use

Potassium hydrogen difluoride is used

in glass production for special optical glasses such as crown and crown flint glass

in glass processing for matt etching

for the chemical shine of aluminum

as an active ingredient in wood preservatives and preservatives

as a component of flux for brazing

for the production of pure fluorine as well as organic and inorganic fluorine compounds

as a catalyst and cement additive

Individual evidence

↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on potassium hydrogen difluoride in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .
↑ Entry on Potassium hydrogendifluoride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .
↑ G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 236-7.
↑ Data sheet about KHF ₂ from Solvay Fluor und Derivate GmbH

[GESTIS-1] ↑ ^a ^b ^c ^d ^e ^f ^g ^h Entry on potassium hydrogen difluoride in the GESTIS substance database of the IFA , accessed on February 1, 2016(JavaScript required) .

[CLP_100.029.233-2] Entry on Potassium hydrogendifluoride in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), accessed on February 1, 2016. Manufacturers or distributors can expand the harmonized classification and labeling .

[3] G. Brauer (Ed.), Handbook of Preparative Inorganic Chemistry 2nd ed., Vol. 1, Academic Press 1963, pp. 236-7.

[4] Data sheet about KHF ₂ from Solvay Fluor und Derivate GmbH