<P> Carbonic acid is a chemical compound with the chemical formula H CO ( equivalently OC ( OH ) ) . It is also a name sometimes given to solutions of carbon dioxide in water ( carbonated water ) , because such solutions contain small amounts of H CO . In physiology , carbonic acid is described as volatile acid or respiratory acid , because it is the only acid excreted as a gas by the lungs . It plays an important role in the bicarbonate buffer system to maintain acid -- base homeostasis . </P>
give the formula for the following substance carbonic acid
H CO ( equivalently OC ( OH ) )