In
inorganic chemistry, a 'bicarbonate' (
IUPAC-recommended nomenclature: 'hydrogencarbonate') is an intermediate form in the
deprotonation of
carbonic acid.
Chemical properties

Structure of bicarbonate
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, H
2CO
3; it is the conjugate acid of CO
32−, the
carbonate ion as shown by these equilibrium reactions.
CO
32- +2 H
2O ⇋ 'HCO
31-' + H
2O + OH
1- ⇋ H
2CO
3 +2 OH
1-
H
2CO
3 +2 H
2O ⇋ 'HCO
31-' + H
3O
1+ + H
2O ⇋ CO
32- +2 H
3O
1+
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.
Uses
The most common salt of the bicarbonate ion is
sodium bicarbonate, NaHCO
3, which is used as
baking soda. When exposed to an
acid such as
acetic acid (
vinegar), bicarbonates release
carbon dioxide. This is used to cause
bread to rise in
baking and to propel toy
rockets.
The bicarbonate/carbonate ionic system is also a
buffer in
blood.
This chemical is also found in the blood. It is a crucial component of the acid/base system of the body (maintaining
homeostasis). 86%-90% of CO
2 in the body is converted into H
2CO
3, a diprotic acid, which also can turn into its basic form HCO
3−. When close to equal amounts of Carbonate ions and Carbonic acid are present it forms a buffer system. This helps maintain the pH of the blood at a level needed for
tissues and
enzymes to work adequately.
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 a use in the digestive system. It neutralizes the exceedingly acidic pH of the stomach after the stomach digests the food.
Bicarbonate Compounds
★
Sodium Bicarbonate
★
Potassium bicarbonate
★
Calcium bicarbonate
★
Ammonium bicarbonate
See also
★
carbon dioxide
★
carbonic acid
★
carbonate
★
hard water
External links
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