Sodium bisulfate, also sodium hydrogen sulfate, has the chemical formula nahso4. The anhydrous form is hygroscopic. Its melting point is poorly defined because it begins to decompose into sodium pyrosulfate and water before it reaches its melting points. solutions of sodium bisulfate are acid, with a 1m solution having ph of 1. 4. In some applications, such solutions can be used instead of sulfuric acid solution. For example, from a solution of sodium bisulfate and sodium acetate it is possible to distill acetic acid. Sodium bisulfate solutions will also liberate co2 from most carbonates.