A HISTORY OF CARBONIC ACID AND THE CENTRAL ROLE OF BICARBONATE IN THE CO₂/H₂O SYSTEM

Carbon dioxide and the related species bicarbonate and carbonate are known for centuries and are deeply involved with modern chemistry knowledge from the beginning. Carbonic acid, by its turn, was intuited more than a century before being synthesized for the first time, which was not obtained, however, without stumbles and mistakes. The equilibrium between HCO₃⁻ and CO₃²⁻ in aqueous medium is free of disputes. However, the interconversion of the other three species is rather controversial. Several papers starting in the beginning of the 19^th century until the present days are critically reviewed in order to understand the controversial history of the CO₂/H₂O system. Finally, experimental evidence and theoretical calculations allow us to place HCO₃⁻ as the central species as the conjugate acid for CO₃²⁻ and conjugate base for two different acids: H₂CO₃ and CO₂.

Keywords:
aqueous solution chemistry; mechanisms of reactions; carbonic acid; carbon dioxide; bicarbonate