Ammonium bicarbonate

Ammonium bicarbonate

Names
IUPAC name Ammonium hydrogen carbonate
Other names Bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, AmBic, powdered baking ammonia, Baking soda
Identifiers
CAS Number	1066-33-7 Y
3D model (Jmol)	Interactive image
ChemSpider	13395 Y
ECHA InfoCard	100.012.647
RTECS number	BO8600000
UNII	45JP4345C9 Y
InChI InChI=1S/CH2O3.H3N/c2-1(3)4;/h(H2,2,3,4);1H3 Y Key: ATRRKUHOCOJYRX-UHFFFAOYSA-N Y InChI=1/CH2O3.H3N/c2-1(3)4;/h(H2,2,3,4);1H3 Key: ATRRKUHOCOJYRX-UHFFFAOYAW
SMILES [O-]C(=O)O.[NH4+]
Properties
Chemical formula	NH4HCO3
Molar mass	79.056 g/mol
Density	1.586 g/cm3
Melting point	41.9 °C (107.4 °F; 315.0 K) decomposes
Solubility in water	11.9 g/100 mL (0 °C) 21.6 g/100 mL (20 °C) 36.6 g/100 mL (40 °C)
Solubility	insoluble in methanol
Hazards
Main hazards	Decomposes to release ammonia
Safety data sheet	ICSC 1333
GHS pictograms
GHS hazard statements	H302
GHS precautionary statements	none
NFPA 704	0 2 0
Flash point	Non-flammable
Related compounds
Other anions	Ammonium carbonate
Other cations	Sodium bicarbonate Potassium bicarbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

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 bicarbonate is produced by combining carbon dioxide and ammonia:

Since ammonium bicarbonate is thermally unstable, the reaction solution is kept cold, which allows the precipitation of the product as white solid. About 100,000 tons were produced in this way in 1997.

Ammonia gas passed into a strong aqueous solution of the sesquicarbonate (a 2:1:1 mixture of (NH₄)HCO₃, (NH₄)₂CO₃, and H₂O) converts it into normal ammonium carbonate ((NH₄)₂CO₃), which can be obtained in the crystalline condition from a solution prepared at about 30 °C. This compound on exposure to air gives off ammonia and reverts to ammonium bicarbonate.

Compositions containing ammonium carbonate have long been known. They were once produced commercially, formerly known as sal volatile or salt of hartshorn. It was obtained by the dry distillation of nitrogenous organic matter such as hair, horn, leather. In addition to ammonium bicarbonate, this material contains ammonium carbamate (NH₄CO₂NH₂), and ammonium carbonate ((NH₄)₂CO₃). It is sometimes called ammonium sesquicarbonate. It possesses a strong ammoniacal smell, and on digestion with alcohol, the carbamate is dissolved leaving a residue of ammonium bicarbonate.

A similar decomposition takes place when the sesquicarbonate is exposed to air.

Ammonium bicarbonate is used in the food industry as a raising agent for flat baked goods, such as cookies and crackers, and in China in steamed buns and Chinese almond cookies. It was commonly used in the home before modern day baking powder was made available. In China it is called edible or food-grade "smelly powder". Many baking cookbooks (especially from Scandinavian countries) may still refer to it as hartshorn or hornsalt (e.g., FI: "hirvensarvisuola", NO: "hjortetakksalt", DK: "hjortetakssalt", SE: "hjorthornssalt", "salt of hart's horn", DE: "Hirschhornsalz"). Although there is a slight smell of ammonia during baking, this quickly dissipates, leaving no taste. It is used in, for example, Swedish "drömmar" biscuits and Danish Christmas biscuits (Hjortetakssalt), and German Lebkuchen. In many cases it may be substituted with baking soda or baking powder or a combination of both, depending on the recipe composition and leavening requirements. Compared to baking soda or potash, hartshorn has the advantage of producing more gas for the same amount of agent, and of not leaving any salty or soapy taste in the finished product, as it completely decomposes into water and gaseous products that evaporate during baking. It cannot be used for moist, bulky baked goods however, such as normal bread or cakes, since some ammonia will be trapped inside and will cause an unpleasant taste.