What Is the Chemical Formula for a Phosphate Ion?

The chemical formula for a phosphate ion is [PO4]3-. The formula indicates that one ion of phosphate contains one atom of phosphorus, represented by the P and four atoms of oxygen, symbolized by O4. The superscript 3- indicates that the ion carries a charge of -3.

In aqueous form, phosphate is derived from phosphoric acid, which is represented by the formula H3PO4, when the acid loses three protons in the form of the three hydrogen ions. Inorganic phosphate can be formed by the reaction between pyrophosphate and water. Phosphate has a molar mass of 94.97 grams per mole. Natural phosphate can be found and mined from some types of rocks.