dihydrogenfosfatjon

The dihydrogen phosphate ion, with the chemical formula H₂PO₄⁻, is a polyatomic anion composed of one phosphorus atom, four oxygen atoms, and two hydrogen atoms. It is one of the three common phosphate species derived from phosphoric acid (H₃PO₄), the others being the hydrogen phosphate ion (HPO₄²⁻) and the phosphate ion (PO₄³⁻). The dihydrogen phosphate ion is formed when phosphoric acid loses one proton.

In aqueous solutions, the relative abundance of dihydrogen phosphate, hydrogen phosphate, and phosphate ions is dependent on the pH. At lower pH values, the dihydrogen phosphate ion is the predominant species. It acts as a weak acid and can donate a proton to form the hydrogen phosphate ion. Conversely, it can accept a proton to form phosphoric acid.

The dihydrogen phosphate ion plays a crucial role in biological systems, particularly in cellular energy transfer as part of adenosine triphosphate (ATP) and as a component of DNA and RNA. It also functions as a buffer in biological fluids and in various chemical processes, helping to maintain a stable pH. Its salts, such as sodium dihydrogen phosphate and potassium dihydrogen phosphate, are commonly used in food additives, fertilizers, and pharmaceuticals.