AskDefine | Define bicarbonate

Dictionary Definition

bicarbonate n : a salt of carbonic acid (containing the anion HCO3) in which one hydrogen atom has been replaced; an acid carbonate [syn: hydrogen carbonate]

User Contributed Dictionary




  1. the univalent anion HCO3; any salt of carbonic acid in which only one of the hydrogen atoms has been replaced
  2. sodium bicarbonate used as a mild antacid; bicabronate of soda


of soda

Extensive Definition

In inorganic chemistry, bicarbonate (IUPAC-recommended nomenclature: hydrogencarbonate) is an intermediate form in the deprotonation of carbonic acid.
Bicarbonate serves a crucial biochemical role in the physiological pH buffering system.

Chemical properties

The bicarbonate ion (hydrogen carbonate) is an anion with the empirical formula HCO3− 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. The bicarbonate ion carries a negative one formal charge and is the conjugate base of carbonic acid, H2CO3; it is the conjugate acid of CO32−, the carbonate ion as shown by these equilibrium reactions.
CO32− +2 H2O ⇋ HCO3− + H2O + OH− ⇋ H2CO3 +2 OH−
H2CO3 +2 H2O ⇋ HCO3− + H3O+ + H2O ⇋ CO32− +2 H3O+
A bicarbonate salt forms when a positively charged ion attaches to the negatively charged oxygen atoms of the ion, forming an ionic compound. Many bicarbonates are soluble in water at standard temperature and pressure, particularly sodium bicarbonate and magnesium bicarbonate; both of these substances contribute to total dissolved solids, a common parameter for assessing water quality.

Biochemical role

Bicarbonate is an alkaline, and a vital component of the pH buffering system

Other uses

The most common salt of the bicarbonate ion is sodium bicarbonate, NaHCO3, which is used as baking soda. When exposed to an acid such as acetic acid (vinegar), sodium bicarbonate releases carbon dioxide. This is used as a leavening agent in baking.
The flow of bicarbonate ions from rocks weathered by the carbonic acid in rainwater is an important part of the carbon cycle.
Bicarbonate also serves in the digestive system. It raises the internal pH of the stomach, after highly acidic digestive juices have finished in their digestion of food.


In diagnostic medicine, the blood value of bicarbonate is one of several indicators of the state of acid-base physiology in the body.
The parameter Standard bicarbonate concentration (SBCe) is the bicarbonate concentration in the blood at a CO2 of 5.33kPa, full oxygen saturation and 37 degrees Celsius.

Bicarbonate compounds


See also

External links

bicarbonate in Czech: Hydrogenuhličitan
bicarbonate in German: Hydrogencarbonate
bicarbonate in Spanish: Bicarbonato
bicarbonate in French: Bicarbonate
bicarbonate in Hebrew: ביקרבונט
bicarbonate in Italian: Idrogenocarbonato
bicarbonate in Dutch: Waterstofcarbonaat (ion)
bicarbonate in Polish: Wodorowęglany
bicarbonate in Portuguese: Bicarbonato
bicarbonate in Finnish: Vetykarbonaatti
bicarbonate in Swedish: Vätekarbonatjon
bicarbonate in Russian: Гидрокарбонаты
bicarbonate in Ukrainian: Гідрокарбонати
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