Chemistry:Ammonium carbonate

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Short description: Chemical used as leavening agent and smelling salt
Ammonium carbonate
Ammonium carbonate.svg
Ball-and-stick model of two ammonium cations and one carbonate anion
Uhličitan amonný.JPG
IUPAC name
Ammonium carbonate
Other names
  • baker's ammonia
  • sal volatile
  • salt of hartshorn
  • E503
3D model (JSmol)
EC Number
  • 233-786-0
UN number 3077
Molar mass 96.09 g/mol
Appearance White powder
Density 1.50 g/cm3
Melting point 58 °C (136 °F; 331 K) (decomposes)
100 g/100 ml (15°C)[1]
25 g/100 ml (20°C)
-42.50·10−6 cm3/mol
Main hazards Irritant
Safety data sheet External MSDS
GHS pictograms GHS07: Harmful
GHS Signal word Warning
H302, H319
Related compounds
Other anions
Ammonium bicarbonate
Ammonium carbamate
Other cations
Sodium carbonate
Potassium carbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Ammonium carbonate is a salt with the chemical formula (NH4)2CO3. 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,[2] and produces a pungent smell when baked.


Ammonium carbonate is produced by combining carbon dioxide and aqueous ammonia. About 80,000 tons/year were produced as of 1997.[2]

An orthorhombic monohydrate is known. It crystallizes in an ammonia solution exposed in a carbon dioxide-rich atmosphere.[3]


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

Ammonium carbonate can spontaneously decompose into ammonium bicarbonate and ammonia:

(NH4)2CO3 → NH4HCO3 + NH3

Which further decompose to carbon dioxide, water and another molecule of ammonia:

NH4HCO3 → H2O + CO2 + NH3


Leavening agent

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 was the precursor to today's more commonly used baking powder.

Originally made from ground deer horn and called hartshorn, today it is called baker's ammonia. It is prepared by the sublimation of a mixture of ammonium sulfate and calcium carbonate and occurs as a white powder or a hard, white or translucent mass.[4] It acts as a heat activated leavening agent and breaks down into carbon dioxide (leavening), ammonia (which needs to dissipate) and water. It is sometimes combined with sodium bicarbonate to mimic as a double acting baking powder and to help mask any ammonia smell not baked out.

It also serves as an acidity regulator and has the E number E503. It can be replaced with baking powder, but this may affect both the taste and texture of the finished product. Baker's ammonia should be used to create thin dry baked goods like crackers and cookies. This allows the strong ammonia smell to bake out. It should not be used to make moist baked items like cake since ammonia is hydrophilic and will leave a strong bitter taste.

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.[5]

Other uses

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, and it is used in aqueous solution as a photographic lens cleaning agent, such as Eastman Kodak's "Kodak Lens Cleaner."

It is also used for luring of apple maggots in Washington (state) , to monitor the spread of the infestation and adjust the borders of the Apple Maggot Quarantine Area.[6]

See also


  1. John Rumble (June 18, 2018) (in English). CRC Handbook of Chemistry and Physics (99th ed.). CRC Press. pp. 4–40. ISBN 1138561630. 
  2. 2.0 2.1 Karl-Heinz Zapp (2012). "Ammonium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_243. ISBN 978-3527306732. 
  3. Fortes, A.D.; Wood, I.G.; Alfè, D.; Hernàndez, E.R.; Gutmann, M.J.; Sparkes, H.A. (2014-12-01). "Structure, hydrogen bonding and thermal expansion of ammonium carbonate monohydrate". Acta Crystallographica Section B 70 (6): 948–962. doi:10.1107/S205252061402126X. ISSN 2052-5206. PMC 4468514. Retrieved 2021-08-20. 
  4. "CFR - Code of Federal Regulations Title 21". 
  5. "Bread". The Engineer's and Mechanic's Encyclopedia. 1. Luke Hebert. 1849. p. 239. 
  6. Yee, Wee L.; Nash, Meralee J.; Goughnour, Robert B.; Cha, Dong H.; Linn, Charles E.; Feder, Jeffrey L. (2014). "Ammonium Carbonate is More Attractive Than Apple and Hawthorn Fruit Volatile Lures to Rhagoletis pomonella(Diptera: Tephritidae) in Washington State". Environmental Entomology 43 (4): 957–968. doi:10.1603/en14038. PMID 24915519. 

H2CO3 He
BeCO3 B C (NH4)2CO3,
O F Ne
Al2(CO3)3 Si P S Cl Ar
Sc Ti V Cr MnCO3 FeCO3 CoCO3 NiCO3 CuCO3 ZnCO3 Ga Ge As Se Br Kr
Rb2CO3 SrCO3 Y Zr Nb Mo Tc Ru Rh Pd Ag2CO3 CdCO3 In Sn Sb Te I Xe
BaCO3   Hf Ta W Re Os Ir Pt Au Hg Tl2CO3 PbCO3 (BiO)2CO3 Po At Rn
Fr Ra   Rf Db Sg Bh Hs Mt Ds Rg Cn Nh Fl Mc Lv Ts Og
La2(CO3)3 Ce2(CO3)3 Pr Nd Pm Sm Eu Gd Tb Dy Ho Er Tm Yb Lu
Ac Th Pa UO2CO3 Np Pu Am Cm Bk Cf Es Fm Md No Lr