Carbonic acid

Carbonic acid
Names
	IUPAC name Carbonic acid
	Other names Oxidocarboxylic acid; Hydroxyformic acid; Hydroxymethanoic acid; Carbonylic acid; Hydroxycarboxylic acid; Dihydroxycarbonyl; Carbon dioxide solution; Aerial acid; Metacarbonic acid;
Identifiers
CAS Number	463-79-6 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:28976 ;
ChEMBL	ChEMBL1161632 ;
ChemSpider	747 ;
DrugBank	DB14531;
ECHA InfoCard	100.133.015
EC Number	610-295-3;
Gmelin Reference	25554
KEGG	C01353 ;
PubChem CID	767;
UNII	142M471B3J ;
CompTox Dashboard (EPA)	DTXSID9043801 ;
	InChI InChI=1S/CH2O3/c2-1(3)4/h(H2,2,3,4) Key: BVKZGUZCCUSVTD-UHFFFAOYSA-N ; InChI=1/H2O3/c2-1(3)4/h(H2,2,3,4) Key: BVKZGUZCCUSVTD-UHFFFAOYAU;
	SMILES O=C(O)O;
Properties
Chemical formula	H; 2CO; 3
Appearance	Colorless gas
Melting point	−53 °C (−63 °F; 220 K) (sublimes)
Boiling point	127 °C (261 °F; 400 K) (decomposes)
Solubility in water	Reacts to form carbon dioxide and water
Acidity (pKa)	pKa1 = 3.6 at 25 °C; pKa2 = 10.329
Conjugate base	Bicarbonate, carbonate
Hazards
NFPA 704 (fire diamond)	0 0 1
Structure
Crystal structure	monoclinic
Space group	p21/c, No. 14
Point group	-
Lattice constant	a = 5.392 Å, b = 6.661 Å, c = 5.690 Å α = 90°, β = 92.66°, γ = 90° (D; 2CO; 3 at 1.85 GPa, 298 K)
Lattice volume (V)	204.12 Å3
Formula units (Z)	4 formula per cell
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Carbonic acid is a chemical compound with the chemical formula H₂C O₃. The molecule rapidly converts to water and carbon dioxide in the presence of water. However, in the absence of water, it is (contrary to popular belief) quite stable at room temperature.^[4]^[5] The interconversion of carbon dioxide and carbonic acid is related to the breathing cycle of animals and the acidification of natural waters.^[3]

In biochemistry and physiology, the name "carbonic acid" is sometimes applied to aqueous solutions of carbon dioxide. These chemical species play an important role in the bicarbonate buffer system, used to maintain acid–base homeostasis.^[6]

^ "Front Matter". Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. P001–4. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
^ W. Hage, K. R. Liedl; Liedl, E.; Hallbrucker, A; Mayer, E (1998). "Carbonic Acid in the Gas Phase and Its Astrophysical Relevance". Science. 279 (5355): 1332–5. Bibcode:1998Sci...279.1332H. doi:10.1126/science.279.5355.1332. PMID 9478889.
^ ^a ^b Benz, Sebastian; Chen, Da; Möller, Andreas; Hofmann, Michael; Schnieders, David; Dronskowski, Richard (September 2022). "The Crystal Structure of Carbonic Acid". Inorganics. 10 (9): 132. doi:10.3390/inorganics10090132. ISSN 2304-6740.
^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 310. ISBN 978-0-08-037941-8.
^ Loerting, Thomas; Tautermann, Christofer; Kroemer, Romano T.; Kohl, Ingrid; Hallbrucker, Andreas; Mayer, Erwin; Liedl, Klaus R.; Loerting, Thomas; Tautermann, Christofer; Kohl, Ingrid; Hallbrucker, Andreas; Erwin, Mayer; Liedl, Klaus R. (2000). "On the Surprising Kinetic Stability of Carbonic Acid (H₂CO₃)". Angewandte Chemie International Edition. 39 (5): 891–4. doi:10.1002/(SICI)1521-3773(20000303)39:5<891::AID-ANIE891>3.0.CO;2-E. PMID 10760883.
^ Acid-Base Physiology 2.1 – Acid-Base Balance by Kerry Brandis.

[iupac2013-1] "Front Matter". Nomenclature of Organic Chemistry: IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. pp. P001–4. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.

[sublime-2] W. Hage, K. R. Liedl; Liedl, E.; Hallbrucker, A; Mayer, E (1998). "Carbonic Acid in the Gas Phase and Its Astrophysical Relevance". Science. 279 (5355): 1332–5. Bibcode:1998Sci...279.1332H. doi:10.1126/science.279.5355.1332. PMID 9478889.

[neutron-3] Benz, Sebastian; Chen, Da; Möller, Andreas; Hofmann, Michael; Schnieders, David; Dronskowski, Richard (September 2022). "The Crystal Structure of Carbonic Acid". Inorganics. 10 (9): 132. doi:10.3390/inorganics10090132. ISSN 2304-6740.

[4] Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 310. ISBN 978-0-08-037941-8.

[lo-5] Loerting, Thomas; Tautermann, Christofer; Kroemer, Romano T.; Kohl, Ingrid; Hallbrucker, Andreas; Mayer, Erwin; Liedl, Klaus R.; Loerting, Thomas; Tautermann, Christofer; Kohl, Ingrid; Hallbrucker, Andreas; Erwin, Mayer; Liedl, Klaus R. (2000). "On the Surprising Kinetic Stability of Carbonic Acid (H₂CO₃)". Angewandte Chemie International Edition. 39 (5): 891–4. doi:10.1002/(SICI)1521-3773(20000303)39:5<891::AID-ANIE891>3.0.CO;2-E. PMID 10760883.

[6] Acid-Base Physiology 2.1 – Acid-Base Balance by Kerry Brandis.

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Names


IUPAC name Carbonic acid^[1]
Other names Oxidocarboxylic acid Hydroxyformic acid Hydroxymethanoic acid Carbonylic acid Hydroxycarboxylic acid Dihydroxycarbonyl Carbon dioxide solution Aerial acid Metacarbonic acid
Identifiers
CAS Number	463-79-6^Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:28976^Y
ChEMBL	ChEMBL1161632^Y
ChemSpider	747^Y
DrugBank	DB14531
ECHA InfoCard	100.133.015
EC Number	610-295-3
Gmelin Reference	25554
KEGG	C01353^Y
PubChem CID	767
UNII	142M471B3J^Y
CompTox Dashboard (EPA)	DTXSID9043801
InChI InChI=1S/CH2O3/c2-1(3)4/h(H2,2,3,4)^Y Key: BVKZGUZCCUSVTD-UHFFFAOYSA-N^Y InChI=1/H2O3/c2-1(3)4/h(H2,2,3,4) Key: BVKZGUZCCUSVTD-UHFFFAOYAU
SMILES O=C(O)O
Properties
Chemical formula	H ₂CO ₃
Appearance	Colorless gas
Melting point	−53 °C (−63 °F; 220 K)^[2] (sublimes)
Boiling point	127 °C (261 °F; 400 K) (decomposes)
Solubility in water	Reacts to form carbon dioxide and water
Acidity (pK_a)	pK_a1 = 3.6 at 25 °C pK_a2 = 10.329
Conjugate base	Bicarbonate, carbonate
Hazards
NFPA 704 (fire diamond)	0 0 1
Structure
Crystal structure	monoclinic
Space group	p21/c, No. 14
Point group	-
Lattice constant	a = 5.392 Å, b = 6.661 Å, c = 5.690 Å α = 90°, β = 92.66°, γ = 90°^[3] (D ₂CO ₃ at 1.85 GPa, 298 K)
Lattice volume (V)	204.12 Å³
Formula units (Z)	4 formula per cell
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Y verify (what is ^YN ?) Infobox references