Ammonium carbonate

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Ammonium carbonate
Ammonium carbonate.png
Ball-and-stick model of two ammonium cations and one carbonate anion
Uhličitan amonný.JPG
Identifiers
CAS number 506-87-6 YesY
ChemSpider 10048 YesY
UNII PDP691CN28 YesY
Jmol-3D images Image 1
Properties
Molecular formula (NH4)2CO3
Molar mass 96.09 g/mol
Appearance White powder
Density 1.50 g/cm3
Melting point 58 °C (136 °F; 331 K)
Boiling point Decomposes
Solubility in water Soluble, decomposes in hot water
Hazards
MSDS External MSDS
Main hazards Irritant
Related compounds
Other anions Ammonium bicarbonate
Other cations Sodium carbonate
Potassium carbonate
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
 YesY (verify) (what is: YesY/N?)
Infobox references

Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. Commercial samples labelled ammonium carbonate no longer contain this compound, but a mixture that has similar ammonia content. Since it readily degrades to gaseous ammonia and carbon dioxide upon heating, it is used as a leavening agent and also as smelling salt. It is also known as baker's ammonia and was a predecessor to the more modern leavening agents baking soda and baking powder. It is a component of what was formerly known as sal volatile and salt of hartshorn.[1]

Production[edit]

Ammonium carbonate is produced by contacting carbon dioxide and ammonia. About 7000 tons/year were produced as of 1997.[1]

Decomposition[edit]

Ammonium carbonate decomposes at standard temperature and pressure through two pathways. Thus any initially "pure" sample of ammonium carbonate will soon become a mixture including various bi-products.

Ammonium carbonate can spontaneously decompose into ammonium bicarbonate and ammonia:

(NH4)2CO3 → NH4HCO3 + NH3

Uses[edit]

Leavening agent[edit]

Ammonium carbonate may be used as a leavening agent in traditional recipes, particularly those from northern Europe and Scandinavia (e.g. Speculoos, Tunnbröd or Lebkuchen). It also serves as an acidity regulator and has the E number E503. It can be substituted with baking powder, but this may affect both the taste and texture of the finished product.

Its use as a leavening agent, with associated controversy, goes back centuries:

In the third kind of bread, a vesicular appearance is given to it by the addition to the dough of some ammoniacal salt, (usually the sub-carbonate,) which becomes wholly converted into a gaseous substance during the process of baking, causing the dough to swell out into little air vessels, which finally bursting, allow the gas to escape, and leave the bread exceedingly porous. Mr. Accum, in his Treatise on Culinary Poisons, has stigmatized this process as "fraudulent," but, in our opinion, most unjustly. The bakers would never adopt it but from necessity: when good yeast cannot be procured, it forms an admirable and perfectly harmless substitute; costing the baker more, it diminishes his profit, while the consumer is benefited by the bread retaining the solid matter, which by the process of fermentation is dissipated in the form of alcohol and carbonic acid gas.[2]

Other uses[edit]

Ammonium carbonate is the main component of smelling salts, although the commercial scale of their production is small. Buckley's cough syrup from Canada today uses ammonium carbonate as an active ingredient intended to help relieve symptoms of bronchitis. It is also used as an emetic. It is also found in smokeless tobacco products, such as Skoal.

See also[edit]

References[edit]

  1. ^ a b Karl-Heinz Zapp "Ammonium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2012, Wiley-VCH, Weinheim. doi:10.1002/14356007.a02_243
  2. ^ "Bread". The Engineer's and Mechanic's Encyclopedia 1. Luke Hebert. 1849. p. 239.