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Other names: ammonium bifluoride, ammonium hydrogen fluoride, ammonium acid fluoride, ammonium hydrofluoride, matte salt.
Ammonium hydrogenfluoride is a compound formed from ammonium fluoride and hydrogenfluoride, with hydrogen fluoride molecules occupying spaces in theammonium fluoride crystal lattice. It is the major constituent inglass-etching fluid (though sometimes replaced by potassium hydrogenfluoride), etching occurring due to the fluorination of silicon:SiO2 (s) + 4[NH4][HF2] (aq) → SiF4 (l) + 4[NH4]F (aq) + 2H2O (l)The structure of [NH4][HF2]contains tetrahedral [NH4]+ cations and linear [HF2] anions. Eachcation is surrounded by four fluorine atroms in a tetrahedron, withhydrogen - fluorine hydrogen bonds present between the hydrogen atomsof the ammonium ion and the fluorine atoms.ammonium bifluoride