What is "carbonic acid"

Carbonic \Car*bon"ic\, a. [Cf. F. carbonique. See Carbon.] (Chem.) Of, pertaining to, or obtained from, carbon; as, carbonic oxide.

Carbonic acid (Chem.), an acid HO.CO.OH, not existing separately, which, combined with positive or basic atoms or radicals, forms carbonates. In common language the term is very generally applied to a compound of carbon and oxygen, CO2, more correctly called carbon dioxide. It is a colorless, heavy, irrespirable gas, extinguishing flame, and when breathed destroys life. It can be reduced to a liquid and solid form by intense pressure. It is produced in the fermentation of liquors, and by the combustion and decomposition of organic substances, or other substances containing carbon. It is formed in the explosion of fire damp in mines, and is hence called after damp; it is also know as choke damp, and mephitic air. Water will absorb its own volume of it, and more than this under pressure, and in this state becomes the common soda water of the shops, and the carbonated water of natural springs. Combined with lime it constitutes limestone, or common marble and chalk. Plants imbibe it for their nutrition and growth, the carbon being retained and the oxygen given out.

Carbonic oxide (Chem.), a colorless gas, CO, of a light odor, called more correctly carbon monoxide. It is almost the only definitely known compound in which carbon seems to be divalent. It is a product of the incomplete combustion of carbon, and is an abundant constituent of water gas. It is fatal to animal life, extinguishes combustion, and burns with a pale blue flame, forming carbon dioxide.

n. a weak unstable acid, H₂CO₃, known only in solution, and as carbonate salts; it is present in carbonated drinks, and sparkling wine, but decomposes to form carbon dioxide and water

n. a weak acid known only in solution; formed when carbon dioxide combines with water

'''Carbonic acid ''' is a chemical compound with the chemical formula HCO (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 HCO. 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.

Carbonic acid, which is a weak acid, forms two kinds of salts, the carbonates and the bicarbonates. In geology, carbonic acid causes limestone to dissolve producing calcium bicarbonate which leads to many limestone features such as stalactites and stalagmites.

The long-held belief that carbonic acid could not exist as a pure compound was disproved, in 1993, by the preparation of the pure substance. This was independently confirmed in 2011.