The bifluoride ion is an

inorganic In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemist ...

anion An ion () is an atom or molecule with a net electrical charge. The charge of an electron is considered to be negative by convention and this charge is equal and opposite to the charge of a proton, which is considered to be positive by conve ...

with the

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbols, ...

. The anion is colorless. Salts of bifluoride are commonly encountered in the reactions of fluoride salts with

hydrofluoric acid Hydrofluoric acid is a solution of hydrogen fluoride (HF) in water. Solutions of HF are colourless, acidic and highly corrosive. It is used to make most fluorine-containing compounds; examples include the commonly used pharmaceutical antidepres ...

. The commercial production of

fluorine Fluorine is a chemical element with the symbol F and atomic number 9. It is the lightest halogen and exists at standard conditions as a highly toxic, pale yellow diatomic gas. As the most electronegative reactive element, it is extremely reactiv ...

involves

electrolysis In chemistry and manufacturing, electrolysis is a technique that uses direct electric current (DC) to drive an otherwise non-spontaneous chemical reaction. Electrolysis is commercially important as a stage in the separation of elements from n ...

of bifluoride salts.

Structure and bonding

The bifluoride ion has a linear, centrosymmetric structure (''D_∞h'' symmetry), with an F− H bond length of 114 pm. The bond strength is estimated to be greater than 155 kJ/mol. In

molecular orbital In chemistry, a molecular orbital is a mathematical function describing the location and wave-like behavior of an electron in a molecule. This function can be used to calculate chemical and physical properties such as the probability of find ...

theory, the atoms are modeled to be held together by a 3-center 4-electron bond.Pimentel, G. C. The Bonding of Trihalide and Bifluoride Ions by the Molecular Orbital Method. ''J. Chem. Phys.'' 1951, ''19'', 446-448.

Reactions

Salts, such as potassium bifluoride and ammonium bifluoride are produced by treating fluoride salts with hydrofluoric acid: :, where = or Potassium bifluoride binds a second equivalent of HF: : Heating these salts releases anhydrous HF.

References

{{reflist Anions Fluorides Bifluorides