KHF2

KHF2, or potassium bifluoride, is an inorganic salt with the formula KHF2. It consists of potassium ions and the bifluoride anion [HF2]− and is commonly described as a salt derived from potassium fluoride and hydrofluoric acid. In solid form it is a white, crystalline, hygroscopic material that readily dissolves in water. When heated, KHF2 decomposes, releasing hydrofluoric acid and leaving potassium fluoride as a residue; this makes it a potential in situ source of HF.

Preparation and properties

Potassium bifluoride is typically produced by reacting potassium fluoride with excess hydrofluoric acid in aqueous solution, followed by crystallization of KHF2 from the solution. It is highly soluble in water and forms acidic solutions due to the presence of fluoride species and possible generation of HF upon hydrolysis or heating. It is stable at room temperature but will decompose upon strong heating to release HF gas or vapor.

Applications

KHF2 is used as a flux in metalworking, including soldering and brazing, where it helps remove oxide layers and promote bonding. It is also employed in glass and ceramic processing for etching and surface treatment, and as a source of fluoride in various inorganic and surface-cleaning applications. Because it can release HF, handling and applications typically require strict safety measures.

Safety and handling

Potassium bifluoride is corrosive and toxic, with hazards similar to other HF-containing compounds. It can cause severe burns and systemic fluoride exposure if inhaled, ingested, or absorbed through the skin. Appropriate PPE, use in a fume hood, proper storage in labeled, moisture-resistant containers, and procedures for HF exposure are essential when working with KHF2.