Bisulfate ions are negatively charged ions with the chemical formula HSO4-. They are formed when sulfuric acid (H2SO4) partially dissociates in water. Bisulfate ions play a role in various chemical reactions and are commonly found in acidic solutions. In addition to their presence in sulfuric acid, bisulfate ions are used in various applications, including food preservation and water treatment. They can act as a mild acid and are often involved in processes that require pH adjustment. Their ability to donate protons makes them important in many biochemical reactions.