Updated 05-May-2020.
Mondo shtuff from around the internet, all about CARBONIC ACID!
<img src='https://ui.adsabs.harvard.edu/styles/img/transparent_logo.svg' alt='Formation of Carbonic Acid (H2CO3) by Surface Reactions of Non-energetic OH Radicals with CO Molecules at Low Temperatures”>Formation of Carbonic Acid (H2CO3) by Surface Reactions of Non-energetic OH Radicals with CO Molecules at Low Temperatures: We present the experimental results of carbonic acid (H2CO3) formation through surface reactions of CO molecules with non-energetic hydroxyl (OH) radicals at 10-40 K. The formation of H2CO3 was clearly identified both in the IR spectra and in the thermally programmed desorption mass spectra. The H2CO3 yield was rather high, amounting to approximately 40%-70% relative to that of CO2 formed by the reaction of CO with OH. The structure of H2CO3 formed by reactions of CO with OH may differ from that formed by energetic processes such as UV irradiation, ion irradiation, and electron irradiation of H2O/CO2 binary ices. In this paper, we envisage some of the possible roles H2CO3 may have in the interstellar medium, such as enriching grain mantles of new molecules via acid-base reactions with basic species and contributing to the formation of the unidentified band at 6.8 μm we suggest possible reasons for its non-detection yet and discuss the restoration of carbonic acid molecules in the gas phase.
<img src='https://ui.adsabs.harvard.edu/styles/img/transparent_logo.svg' alt='Infrared and mass spectral studies of proton irradiated H 2O + CO 2 ice: Evidence for carbonic acid”>Infrared and mass spectral studies of proton irradiated H 2O + CO 2 ice: Evidence for carbonic acid: The effects of proton irradiation on mixed H 2O + CO 2 (1:1) ices at 20 K were investigated by infrared and mass spectroscopy. Infrared bands due to several radical (HCO, CO 3) and molecular (CO) product species were identified. In addition, several new broad and complex i.r. features were observed. On slow warming, the broad features evolved into a 215-250 K residual film whose absorptions have been tentatively assigned to carbonic acid. This identification agrees with the spectral data for irradiated H 2O + 13CO 2 ice and the results of an approximate normal coordinate analysis.
My botty best at summarizing from Wikipedia: carbonic acid 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 . carbonic acid causes limestone to dissolve, producing calcium bicarbonate . in the absence of a catalyst, the equilibrium is reached quite slowly . the addition of two molecules of water to CO2 would give orthocarbonic acid, C(OH)4 . addition of base to excess of carbonic acid gives bicarbonate (hydrogen carbonate) with excess base, carbon carbonic acid may play a pivotal role in protonating nitrogen bases in blood serum . extra dissolved carbon dioxide has caused ocean’s average surface pH to shift . this is known as ocean acidification, even though ocean carbonic acid is specifically diprotic and so has two protons that may dissociate from the parent molecule . there are two dissociation constants, the first of which is for the dissociations into the bicarbon sulfurous acid (H2SO3) exists in equilibrium with substantial amounts of unhydrated sulfur dioxide . the second constant is for the dissociation of the bicarbonate ion into the carbonate-ion CO32 in the total range of pressure, the pH is always much lower than pKa2 (= 10.3) so that the CO32 concentration is always negligible with respect to HCO3 concentration . for vanishing between 2.5 and 10 atm, the pH crosses the pKa1 value (3.60) at high pressures . another route to form carbonic acid is protonation of bicarbonates (HCO3-) with -H2CO3 sublimes at 230 – 260 K largely without decomposition . matrix-isolation infared spectroscopy allows for the recording of single molecules of H claim disputed in a PhD thesis submitted in January 2014 . instead, isotope labeling experiments point to involvement of carbonic acid monomethyl ester (CAME) It is not clear whether carbonic acid prepared in this way needs to be considered as -H2CO3 . the structures of and have not been characterized crystallographically . A. (1969 Exchange between carbon dioxide and water”. J. Phys. Chem. 73 (335): 3351. doi:10.1021/j100844a033. Modern Inorganic Chemistry (2nd Edn.). New York: McGraw-Hill. ISBN 978-0-07-112651-9. Moore, M. H.; Khanna, R. (1991). “In Spectrochimica Acta. 47A (2): 255–262. Bibcode:1991AcSpA..47..255M. doi:10.1016/0584-8539( “Carbonic Acid in the Gas Phase and Its Astrophysical Relevance”. Science. 279 (5355): 1332–1335. Bibcode:1998Sci…279.1332H. doi: PMID 9478889. Hage, W.; Hallbrucker, A.; Mayer, E. (1995). “A Polymorph of Carbonic Acid and Its Possible Astrophysical Relevance”. Faraday Trans. 91 (17): 2823–2826. Bibcode:1995JCSFT..91.2823H. doi:10.1039/ft9959102823.