Potassium bifluoride

Potassium bifluoride
Names
	IUPAC name Potassium bifluoride
	Other names Potassium hydrogen difluoride
Identifiers
CAS Number	7789-29-9 ;
3D model (JSmol)	Interactive image;
ChemSpider	35308426 ;
ECHA InfoCard	100.029.233
EC Number	232-156-2;
PubChem CID	11829350;
RTECS number	TS6650000;
UNII	880X05W53M ;
UN number	1811
CompTox Dashboard (EPA)	DTXSID10894159 ;
	InChI InChI=1S/F2H.K/c1-3-2;/q-1;+1 Key: FLCWRBFUWAZYGV-UHFFFAOYSA-N ;
	SMILES [H-](F)F.[K+];
Properties
Chemical formula	HF2K
Molar mass	78.103 g/mol
Appearance	colourless solid
Odor	slightly acidic
Density	2.37 g/cm3
Melting point	238.7 °C (461.7 °F; 511.8 K)
Boiling point	decomposes
Solubility in water	24.5 g/100 mL (0 °C) ; 30.1 g/100mL (10 °C) ; 39.2 g/100 mL (20 °C) ; 114.0 g/100 mL (80 °C)
Solubility	soluble in ethanol
Structure
Crystal structure	monoclinic
Thermochemistry
Std molar; entropy (So298)	45.56 J/(mol K)
Std enthalpy of; formation (ΔfH⦵298)	-417.26 kJ·K−1*mol−1
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H310, H314
Precautionary statements	P260, P262, P264, P270, P280, P301+P310, P301+P330+P331, P302+P350, P303+P361+P353, P304+P340, P305+P351+P338, P310, P321, P322, P330, P361, P363, P405, P501
Flash point	non flammable
Related compounds
Other anions	Potassium fluoride
Other cations	Sodium bifluoride, ammonium bifluoride
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
	(what is ?)
	Infobox references

Potassium bifluoride is the inorganic compound with the formula KHF₂. This colourless salt consists of the potassium cation and the bifluoride (HF₂⁻) anion. The salt is used in etchant for glass. Sodium bifluoride is related and is also of commercial use as an etchant as well as in cleaning products.^[3]

Synthesis and reactions[]

The salt was prepared by Edmond Frémy by treating potassium carbonate or potassium hydroxide with hydrofluoric acid:

2 HF + KOH → KHF₂ + H₂O

With two more equivalents of HF, KH₂F₃ (CAS#12178-06-2, m.p. 71.7 C) is produced:

2 HF + KHF₂ → KH₂F₃

Thermal decomposition of KHF₂ gives hydrogen fluoride:

KHF₂ → HF + KF

Applications[]

The industrial production of fluorine entails the electrolysis of molten KHF₂ and KH₂F₃.^[3] The electrolysis of KHF₂ was first used by Henri Moissan in 1886.

References[]

^ Westrum, Edgar F., Jr.; Pitzer, Kenneth S. (June 1949). "Thermodynamics of the System KHF2-KF-HF, Including Heat Capacities and Entropies of KHF2, and KF. The Nature of the Hydrogen Bond in KHF2". J. Am. Chem. Soc. 71 (6): 1940–1949. doi:10.1021/ja01174a012.
^ "Potassium bifluoride". pubchem.ncbi.nlm.nih.gov. Retrieved 27 December 2021.
^ ^a ^b Aigueperse, Jean; Mollard, Paul; Devilliers, Didier; Chemla, Marius; Faron, Robert; Romano, René; Cuer, Jean Pierre (2000). "Fluorine Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_307.

‹ The template below (Fluorine compounds) is being considered for merging. See templates for discussion to help reach a consensus. ›

[Pitzer-1] Westrum, Edgar F., Jr.; Pitzer, Kenneth S. (June 1949). "Thermodynamics of the System KHF2-KF-HF, Including Heat Capacities and Entropies of KHF2, and KF. The Nature of the Hydrogen Bond in KHF2". J. Am. Chem. Soc. 71 (6): 1940–1949. doi:10.1021/ja01174a012.

[2] "Potassium bifluoride". pubchem.ncbi.nlm.nih.gov. Retrieved 27 December 2021.

[Aigueperse-3] Aigueperse, Jean; Mollard, Paul; Devilliers, Didier; Chemla, Marius; Faron, Robert; Romano, René; Cuer, Jean Pierre (2000). "Fluorine Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a11_307.

[1]

[2]

[3]

Potassium bifluoride

Contents

Synthesis and reactions[]

Applications[]

See also[]

References[]