Potassium bisulfate (chemical formula: KHSO4) is potassium bisulfate. Rare jarosite and fibrous jarosite exist in nature. It is an acid salt with strong acidity. Chemicalbook is generally used as an acidic reagent in red wine industry and analytical chemistry. Similar to the aqueous solution of potassium sulfate and sulfuric acid, insoluble potassium sulfate will precipitate when mixed with ethanol.