Hydrogen carbonate

Bicarbonate

Names
Systematic IUPAC name Hydroxidodioxidocarbonate(1−)
Other names Hydrogencarbonate
Identifiers
CAS Number	71-52-3 Y
3D model (Jmol)	Interactive image
3DMet	B00080
Beilstein Reference	3903504
ChEBI	CHEBI:17544 Y
ChEMBL	ChEMBL363707 Y
ChemSpider	749 Y
Gmelin Reference	49249
KEGG	C00288 Y
PubChem	769
UNII	HN1ZRA3Q20 Y
InChI InChI=1S/CH2O3/c2-1(3)4/h(H2,2,3,4)/p-1 Y Key: BVKZGUZCCUSVTD-UHFFFAOYSA-M Y
SMILES OC([O-])=O
Properties
Chemical formula	HCO− 3
Molar mass	61.0168 g mol−1
log P	−0.82
Acidity (pKa)	10.3 (Conjugate acid of carbonate)
Basicity (pKb)	7.7 (Conjugate base of carbonic acid)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogen carbonate) is an intermediate form in the deprotonation of carbonic acid. It is a polyatomic anion with the chemical formula HCO−
3.

Bicarbonate serves a crucial biochemical role in the physiological pH buffering system.

The term "bicarbonate" was coined in 1814 by the English chemist William Hyde Wollaston. The prefix "bi" in "bicarbonate" comes from an outdated naming system and is based on the observation that there is twice as much carbonate (CO2−
3) per sodium ion in sodium bicarbonate (NaHCO₃) and other bicarbonates than in sodium carbonate (Na₂CO₃) and other carbonates. The name lives on as a trivial name.

The bicarbonate ion (hydrogencarbonate ion) is an anion with the empirical formula HCO−
3 and a molecular mass of 61.01 daltons; it consists of one central carbon atom surrounded by three oxygen atoms in a trigonal planar arrangement, with a hydrogen atom attached to one of the oxygens. It is isoelectronic with nitric acid HNO
3. The bicarbonate ion carries a negative one formal charge and is the conjugate base of carbonic acid H
2CO
3; at the same time, it is the conjugate acid of CO2−
3, the carbonate ion, as shown by these equilibrium reactions: