Ammonium carbonate

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.[1]

Ammonium carbonate
Ammonium carbonate
Ball-and-stick model of two ammonium cations and one carbonate anion
Uhličitan amonný
IUPAC name
Ammonium carbonate
Other names
  • baker's ammonia
  • sal volatile
  • salt of hartshorn
  • E503
3D model (JSmol)
ECHA InfoCard 100.007.326
EC Number
  • 233-786-0
E number E503(i) (acidity regulators, ...)
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)
Boiling point Decomposes
100g/100ml(20°C),decomposes in hot water
-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).


Ammonium carbonate is produced by combining carbon dioxide and aqueous ammonia. About 80000 tons/year were produced as of 1997.[1]


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Originally made from ground deer horn and called hartshorn.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. The ingredient ammonium carbonate is a mix of ammonium bicarbonate (NH4HCO3) and ammonium carbamate (NH2COONH4). 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.[2] 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.[3]

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."


A teaspoon of baker's ammonia can be substituted with a teaspoon baking powder plus a teaspoon baking soda.

See also


  1. ^ a b Karl-Heinz Zapp (2012). "Ammonium Compounds". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a02_243.CS1 maint: uses authors parameter (link)
  2. ^ "CFR - Code of Federal Regulations Title 21". Retrieved 2018-02-07.
  3. ^ "Bread". The Engineer's and Mechanic's Encyclopedia. 1. Luke Hebert. 1849. p. 239.

Aminolysis (/am·i·nol·y·sis/ amino meaning "contains NH2 group", and lysis meaning "to unbind") is any chemical compound reacts with a molecule of ammonia or an amine and causes a molecule to split into two parts, containing the addition of (or substitution by) an amino group —NH—. The subset of aminolysis reactions involving ammonia is known as ammonolysis.α

Ammonium bicarbonate

Ammonium bicarbonate is an inorganic compound with formula (NH4)HCO3, simplified to NH5CO3. The compound has many names, reflecting its long history. Chemically speaking, it is the bicarbonate salt of the ammonium ion. It is a colourless solid that degrades readily to carbon dioxide, water and ammonia.

Ammonium chlorate

Ammonium chlorate is an inorganic compound with the formula NH4ClO3.

It is obtained by neutralizing chloric acid with either ammonia or ammonium carbonate, or by precipitating barium, strontium or calcium chlorates with ammonium carbonate or ammonium sulfate, producing the respective carbonate or sulfate precipitate and an ammonium chlorate solution. Ammonium chlorate crystallizes in small needles, readily soluble in water.

The bitartrate method candidate be used if exotic chlorate are inaccessible or need to be synthesized. Warm solutions of potassium chlorate and ammonium bitartrate are needed need warm solutions. The latter can be synthesized by adding aqueous ammonia to an excess of tartric acid. Then, a double displacement reaction will result in precipitation of potassium bitartrate.

On heating, ammonium chlorate decomposes at about 102 °C, with liberation of nitrogen, chlorine and oxygen. It is soluble in dilute aqueous alcohol, but insoluble in strong alcohol. This compound is a strong oxidizer and should never be stored with flammable materials.

Ammonium chlorate is a very unstable oxidizer and will decompose, sometimes violently, at room temperature. This results from the mixture of the reducing ammonium cation and the oxidizing chlorate anion. Even solutions are known to be unstable. Because of the dangerous nature of this salt it should only be kept in solution when needed, and never be allowed to crystallize.

Ammonium uranyl carbonate

Ammonium uranyl carbonate (UO2CO3·2(NH4)2CO3) is known in the uranium processing industry as AUC and is also called uranyl ammonium carbonate. This compound is important as a component in the conversion process of uranium hexafluoride (UF6) to uranium dioxide (UO2). The ammonium uranyl carbonate is combined with steam and hydrogen at 500–600 °C to yield UO2. In another process aqueous uranyl nitrate, known as uranyl nitrate liquor (UNL) is treated with ammonium bicarbonate to form ammonium uranyl carbonate as a solid precipitate. This is separated from the solution, dried with methanol and then calcinated with hydrogen directly to UO2 to obtain a sinterable grade powder. The ex-AUC uranium dioxide powder is free-flowing, relatively coarse (10 µ) and porous with specific surface area in the range of 5 m2/g and suitable for direct pelletisation, avoiding the granulation step. Conversion to UO2 is often performed as the first stage of nuclear fuel fabrication.The AUC process is followed in South Korea and Argentina. In the AUC route, calcination, reduction and stabilization are simultaneously carried out in a vertical fluidized bed reactor. In most countries, sinterable grade UO2 powder for nuclear fuel is obtained by the ammonium diuranate (ADU) process, which requires several more steps.

Ammonium uranyl carbonate is also one of the many forms called yellowcake; in this case it is the product obtained by the heap leach process.

Barium chlorate

Barium chlorate, Ba(ClO3)2, is a white crystalline solid, the barium salt of chloric acid. It is an irritant and toxic, as are all soluble barium compounds. It is sometimes used in pyrotechnics to produce a green color. It also finds use in the production of chloric acid.

Bucherer–Bergs reaction

The Bucherer–Bergs reaction is the chemical reaction of carbonyl compounds (aldehydes or ketones) or cyanohydrins with ammonium carbonate and potassium cyanide to give hydantoins. The reaction is named after Hans Theodor Bucherer.

Overall Reaction

Casein paint

Casein paint, derived from milk casein (milk protein), is a fast-drying, water-soluble medium used by artists.

Colorimetric analysis

Colorimetric analysis is a method of determining the concentration of a chemical element or chemical compound in a solution with the aid of a color reagent. It is applicable to both organic compounds and inorganic compounds and may be used with or without an enzymatic stage. The method is widely used in medical laboratories and for industrial purposes, e.g. the analysis of water samples in connection with industrial water treatment.

Copper(II) oxide

Copper(II) oxide or cupric oxide is the inorganic compound with the formula CuO. A black solid, it is one of the two stable oxides of copper, the other being Cu2O or cuprous oxide. As a mineral, it is known as tenorite. It is a product of copper mining and the precursor to many other copper-containing products and chemical compounds.

Copper pesticide

A copper pesticide is a copper compound used as a pesticide or fungicide. In the UK the Soil Association (one of the organic certification authorities) permits farmers to use some copper fungicides on organic land used for the production of certified organic crops only if there is a major threat to crops. The compounds permitted are copper sulfate, copper hydroxide, cuprous oxide, copper oxychloride, copper ammonium carbonate (at a maximum concentration of 25 g/l), and copper octanoate. According to the Soil Association the total copper that can be applied to organic land is 6kg/ha/year. This limit is designed so that the amount of copper in the soil does not exceed the limits specified in the Soil Association standards for heavy metals.

Coriaria thymifolia

Coriaria thymifolia, known as shanshi(Ecuador), tutu-papa, tutu-heu-heu, toot plant (New Zealand), or ink plant is a shrub found in montane environments throughout the Americas and Pacific Islands. The plant bears dark blue, almost black, blossom-shaped clustered berries that resemble black liquorice. The fruit is widely known as toxic to livestock, with many sheep, cattle, goats, and in one recorded case even a captive elephant dying from "toot poisoning" in New Zealand, and cases of animal deaths also recorded in South America. In humans the plant reportedly has hallucinogenic, possibly deliriant, properties when consumed, and is sought out for these purposes by Ecuadorian peasants. Reported effects include a sensation of flight. The cause of the toxic and hallucinogenic effects is not known, but is suspected to be an unidentified glycoside. Despite this usage, and the plant's toxicity, human fatalities from C. thymifolia poisoning are considered rare, although it can easily cause violent convulsions. The dark-coloured fruit are also used in South America to make a traditional ink called chanchi. Animals poisoned by C. thymifolia have been successfully treated using ammonium carbonate, with lime and other alkalies used in humans.


Hartshorn is the horn of male red deer.


Hydantoin, or glycolylurea, is a heterocyclic organic compound with the formula CH2C(O)NHC(O)NH. It is a colorless solid that arises from the reaction of glycolic acid and urea. It is an oxidized derivative of imidazolidine. In a more general sense, hydantoins can refer to a groups and a class of compounds with the same ring structure as the parent. For example, phenytoin (mentioned below) has two phenyl groups substituted onto the number 5 carbon in a hydantoin molecule.


Mandelkubb is a Swedish pastry with bitter almonds as the main ingredient, mixed with flour, sugar, eggs and baker's ammonia. They are often garnished with nib sugar.

Raschig hydroxylamine process

The Raschig process for the production of hydroxylamine is one of three chemical processes developed by German chemist Friedrich Raschig. The main step in this process, patented by Raschig in 1887, is the reduction of nitrite with bisulfite towards hydroxylamine disulfonate, which is hydrolysed to hydroxylammonium sulfate. Most of the hydroxylamine produced is used in the manufacture of caprolactam, the precursor to the polymer Nylon 6.The commercially used Raschig process consists of the following steps:

ammonium carbonate solution is prepared by reacting ammonia, carbon dioxide and water

an alkaline solution of ammonium nitrite is formed by reacting ammonium carbonate solution with nitrogen oxides

ammonium nitrite is converted to hydroxylamine disulfonate with sulfur dioxide

hydroxylamine disulfonate is hydrolysed to hydroxylammonium sulfate

Rubidium carbonate

Rubidium carbonate, Rb2CO3, is a convenient compound of rubidium; it is stable, not particularly reactive, and readily soluble in water, and is the form in which rubidium is usually sold.

Salter Science

Salter Science was a brand of science kits sold by Thomas Salter Ltd., a Scotland-based company which manufactured toys and science activity kits for children. Kits included activities with electricity, microscopy, magnetism and crystal gardens, but the company is probably best known for their chemistry sets. The company also produced other toys related to TV series such as 'KOJAK' ACTION SET and also produced Crafts Plaster Moulding Set's Frog & Owl.Thomas Salter Ltd. was founded in London in 1913, moved to Glenrothes, Fife, and closed in 1992.Chemistry sets from Salter Science included a various number of chemicals, which were numbered, so that the numbers were the same across the sets. Some of the chemicals included were:

Copper Sulfate

Sodium Carbonate

Calcium Oxychloride

Iron Filings

Calcium Hydroxide

Sodium Hydrogen Sulfate

Tartaric Acid

Methyl Orange

Ferrous Sulfate

Ammonium Carbonate

Magnesium Ribbon

Copper Wire

Ammonium Chloride

Sodium Thiosulfate

Sodium Perborate

Cobalt Chloride

Also commonly included were small glass test tubes, a spatula, a funnel, corks, a small bottle brush and a test tube rack. Larger sets also included a methylated spirit burner for heating.

Smelling salts

Smelling salts, also known as ammonia inhalants, spirit of hartshorn or sal volatile, are chemical compounds often used to arouse consciousness.


Tunnbröd (Swedish: [²tɵnːbrøːd]; literally "thinbread") is the Swedish version of flatbread and properly belongs to northern Swedish cuisine where housewives share a common bakery to produce it. Tunnbröd can be soft or crisp, and comes in many variants depending on choice of grain, leavening agent (or lack thereof) and rolling pin. The dough is made from any combination of wheat, barley and rye; the leavening agent can be both yeast and ammonium carbonate.

Soft tunnbröd is commonly used as a wrap for other food, like a crêpe or tortilla. A popular fast food dish is soft tunnbröd rolled around mashed potatoes and a hot dog, known as tunnbrödsrulle (tunnbröd roll).

Another traditional old Swedish method of eating soft tunnbröd is burrito-style, combined with mashed potatoes and roasted herring.

Traditionally, tunnbröd is eaten with surströmming (fermented herring) and as dopp i grytan (lit. "dip in the pot"). A spiced soft bread is generally used for this, and the bread is soaked in the stock left from cooking the Christmas ham. Crisp tunnbröd differs from knäckebröd in being thinner and more compact, containing fewer air bubbles.

The consistency and taste of tunnbröd can vary a lot, as recipes and preparation of the bread differ depending on the bakery. Traditionally housewives would keep recipes a closely guarded secret only shared with other family members.


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