The formula for carbonic acid is expressed as H2CO3. It can also be written as OC(OH)2. Carbonic acid is a weak acid comprised of hydrogen, carbon and oxygen, as expressed by its chemical formula.
The chemical reaction that forms carbonic acid is written as CO2 + H2O -> H2CO3. CO2 stands for carbon dioxide and H2O stands for water; the combination of the two forms carbonic acid. Carbonic acid is used to create the carbonated water needed for the production of soft drinks as well as other bubbling drinks such as sparkling wine. Carbonic acid is also used in the creation of carbonate salts.