What type of salt is produced when a metal reacts with phosphoric acid?
The classic reaction of a metal plus an acid produces a metal salt plus hydrogen. The chemical symbol for phosphoric acid is H3PO4. And this is the structure of phosphoric acid. Phosphoric acid has three acidic protons. In a reaction with a metal, these protons are lost, forming the anion PO4 3−. The name for this ion is phosphate. So the general reaction of a metal plus phosphoric acid produces a metal phosphate plus hydrogen.
For instance, the reaction of zinc with the phosphoric acid produces zinc phosphate plus hydrogen. And here’s the balanced reaction. A metal plus phosphoric acid produces a metal phosphate. And phosphate is the type of salt. So the type of salt produced when a metal reacts with phosphoric acid is phosphate.
A quick way of remembering this is we take the “oric” from phosphoric and replace it with “ate” in phosphate. In the same way, we replace “uric” from sulphuric with “ate” in sulphate and the “ic” in nitric with “ate” in nitrate. However, we don’t do this with hydrochloric. Instead, we go from hydrochloric to chloride. We apply different rules depending on whether the acid contains oxygen or not. Phosphoric acid, sulfuric acid, and nitric acid all produce anions that contain oxygen, phosphate, sulfate, and nitrate, whereas the chloride ion contains no oxygen.
So the type of salt produced when a metal reacts with phosphoric acid is a phosphate salt.