Phosphoric acid
Phosphoric acid (H3PO4) is the most important acid of the element phosphorus. It occupies a central position among the inorganic acids and is used in many different industries.
As phosphoric acid ester and in the form of polyphosphates, phosphoric acid also plays an elementary role in the human metabolism. Among other things, it is an important component of the energy transmitter adenosine triphosphate (ATP). Phosphoric acid is also a component of DNA, RNA and many coenzymes. Together with calcium, it forms hydroxyapatite in the body, which is what bones and teeth are made of.
Properties of phosphoric acid
In high concentrations, phosphoric acid is corrosive. It is a colourless and odourless solid. It is a weak to moderately strong, three-proton acid. The salts and esters of phosphoric acid are called phosphates, the latter are also known as organophosphates.
The chemical is strongly hygroscopic and can be mixed with water. It is usually distributed as an 83 to 90 percent aqueous solution. Phosphoric acid has good conductivity.
Phosphoric acid is produced from raw phosphate - usually the mineral apatite - and sulphuric acid, hydrochloric acid or nitric acid. Alternatively, so-called thermal phosphoric acid can be produced by burning phosphorus to form phosphorus pentoxide with subsequent hydrolysis.