Phosphoric Acid is prepared commercially by heating calcium phosphate rock with sulfuric acid; purer grades may be prepared by treating red phosphorus with nitric acid. Pure phosphoric acid is a crystalline solid melting point 42 C ; in less concentrated form it is a colorless syrupy liquid. It is a tribasic acid (having three replaceable hydrogen atoms) and forms orthophosphate salts with one, two, or all three of the hydrogen replaced by some other positive ion.
Application ： Phosphoric acid is used primarily in the manufacture of fertilizers, detergents, and pharmaceuticals. In the steel industry, it is used to clean and rust-proof the product. It is also used as a flavoring agent in carbonated beverages (read the ingredients list on a can of Coca-Cola), beer, jams and jellies, and cheeses. In foods, phosphoric acid provides a tart, acidic flavor.
