What Is Potassium Hydrogen Sulfate?
Potassium hydrogen sulfate (KHSO4), also known as potassium bisulfate, is an odorless, colorless, or white crystalline salt with a molecular weight of 136.17 and a CAS number of 7646-93-7. It naturally occurs as the mineral mercallite, which is colorless or sky-blue and sometimes found in stalactites.
Uses of Potassium Hydrogen Sulfate
This compound is used as a flux in mineral analysis, for cleaning platinum apparatus, and in the production of potassium tartrate for winemaking. It’s also a precursor to potassium persulfate, serving as a powerful oxidizing agent in fertilizers and food preservatives.
Properties of Potassium Hydrogen Sulfate
With a melting point of 197°C and decomposing at around 300°C, KHSO4 has a density of 2.24 g/cm3 and is soluble in water (50 g/100 mL). Its aqueous solution is highly acidic but decomposes in ethanol, showcasing both orthorhombic and monoclinic crystal structures.
Production and Reactions
KHSO4 is produced via reactions such as K2SO4 + H2SO4 → 2 KHSO4, and its thermal decomposition leads to potassium pyrosulfate (K2S2O7), further breaking down into potassium sulfate (K2SO4) and sulfur trioxide (SO3) above 600°C.
Regulatory and Safety Information
While not regulated under various safety, it is classified as corrosive under transportation laws. Handling precautions include storage in cool, dark places in non-metallic containers, usage in ventilated areas or outdoors, and personal protective equipment to prevent exposure.