Chemical Formula: H3PO4 Density: 98g/ml Phosphoric acid is often used to acidify foods and beverages such as carious colas. It provides a tangy and sour taste. We use Phosphoric acid to treat the by-product of biodiesel. after methanol extraction, using phosphoric acid allows a clean separation of the glycerin and soaps. If done correctly, it can yield 90% pure glycerin. May also be used as a rust remover/inhibitor. Dilute to a 25-50% concentration with water and soak rusted metal parts. Over time, rust will remove and the phosphoric acid reacts with the metal to create a rust inhibiting barrier on the metal. Be sure to use gloves! Great for cleaning residue from metals.