Ferric Ammonium EDTA Solution is normally used as a photographic chemical for a bleaching agent in the process of colour washing. It is also used as a complexing, and oxidizing agent & as a fertilizer and catalyst. EDTA acid are colourless, water-soluble solid that are widely used to dissolve scale. The usefulness of these ammonium salts arise because of its role as a chelating agent, i.e. its ability to "sequester" metal ions such as Ca2+ and Fe3+.