bisulfates

Bisulfates are salts that contain the bisulfate anion, HSO4−. They occur when sulfuric acid is only partially neutralized, and are commonly encountered as alkali or ammonium salts such as sodium bisulfate (NaHSO4), potassium bisulfate (KHSO4), and ammonium bisulfate ((NH4)HSO4). They are distinct from bisulfites, which contain the HSO3− anion.

In water, bisulfate salts produce acidic solutions because the bisulfate anion can donate a proton to water, forming sulfate (SO4^2−) and hydronium. The related second dissociation of sulfuric acid has a pKa around 1.99, which gives bisulfates their characteristic acidity in solution. As solid salts, bisulfates are typically white to off-white and highly soluble in water; many exist as hydrates.

Preparation and occurrence: Bisulfates are produced by partial neutralization of sulfuric acid or by acidifying sulfates. They are used in various industries as buffering and acidifying agents. Common examples include NaHSO4, KHSO4, and (NH4)HSO4. Applications include drying agents and pH adjusters in cleaning products, pool and water-treatment formulations, textile finishing, and as reagents in chemical synthesis and metal processing.

Safety and handling: Bisulfates can be irritants and are corrosive in concentrated form. They should be handled with appropriate PPE, and stored away from incompatibles. Inhalation of dust and prolonged skin or eye contact should be avoided.