Phosphoric acid is a mineral (inorganic) acid having the chemical formula H3PO4. Orthophosphoric acid refers to phosphoric acid, which is the IUPAC name for this compound. The prefix ortho- is used to distinguish the acid from related phosphoric acids, called polyphosphoric acids.In addition to being a chemical reagent, phosphoric acid has a wide variety of uses, including as a rust converter, food additive, dental and orthopedic etchant, electrolyte, soldering flux, dispersing agent, industrial etchant, fertilizer feedstock, and component of home cleaning products. Phosphoric acids and phosphates are also important in biology.