Phosphoric acid (also known as
orthophosphoric acid or
phosphoric(V) 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. Orthophosphoric acid is a non-
toxic acid, which, when pure, is a
solid at room
temperature and
pressure. The
conjugate base of phosphoric acid is the dihydrogen phosphate ion, , which in turn has a conjugate base of hydrogen phosphate, , which has a conjugate base of
phosphate, . Phosphates are nutritious for all forms of life.