Potassium bifluoride is the inorganic compound with the formula K[HF2]. This colourless salt consists of the potassium cation (K+) and the bifluoride anion ([HF2]−). The salt is used as an etchant for glass. Sodium bifluoride is related and is also of commercial use as an etchant as well as in cleaning products.[3]
The salt was prepared by Edmond Frémy by treating potassium carbonate or potassium hydroxide with hydrofluoric acid:
With one more equivalent of HF, K[H2F3] (CAS#12178-06-2, m.p. 71.7 C)[clarification needed] is produced:
Thermal decomposition of K[HF2] gives hydrogen fluoride:
The industrial production of fluorine entails the electrolysis of molten K[HF2] and K[H2F3].[3] The electrolysis of K[HF2] was first used by Henri Moissan in 1886.