EC Number 232-151-5. MDL number MFCD00011398. After hydrogen fluoride, KF is the primary source of the fluoride ion for applications in manufacturing and in chemistry. It is an alkali halide and occurs naturally as the rare mineral carobbiite. NACRES NA.23 How to Write the Formula for Potassium fluoride (KF) - YouTube Best Answer: Because calcium sulfide, CaS, have a charge value of 2 and in potassium fluoride, KF, a charge value of 1Ca 2+ and S 2-K 1+ and F 1- Structure, properties, spectra, suppliers and links for: Potassium fluoride, 7789-23-3. Potassium fluoride is the chemical compound with the formula KF. Linear Formula KF . Beilstein/REAXYS Number 3902818 . Potassium fluoride ≥99.97% trace metals basis CAS Number 7789-23-3. Molecular Weight 58.10 . PubChem Substance ID 24853749. Solutions of KF will etch glass due to the formation of soluble fluorosilicates, although HF is more effective.