ammonium bicarbonate

Ammonium bicarbonate
IUPAC name	Ammonium hydrogen carbonate
Other names	Bicarbonate of ammonia Hartshorn Baking ammonia
Identifiers
CAS number	1066-33-7 Y
RTECS number	BO8600000
SMILES	[O-]C(=O)O.[NH4+]
InChI	1/CH2O3.H3N/c2-1(3)4;/h(H2,2,3,4);1H3
InChI key	ATRRKUHOCOJYRX-UHFFFAOYAW
ChemSpider ID	13395
Properties
Molecular formula	NH4HCO3
Molar mass	79.056 g/mol
Density	1.586 g/cm3
Melting point	107.5 ºF, decomp.
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
MSDS	ICSC 1333
EU Index	Not listed
Main hazards	Decomposes to release ammonia
NFPA 704	0 2 0
Flash point	Non-flammable
Related compounds
Other anions	Ammonium carbonate
Other cations	Sodium bicarbonate Potassium bicarbonate
Y (what is this?)  (verify) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Ammonium bicarbonate, a compound with formula NH₄(C(=O)OHO), also called bicarbonate of ammonia, ammonium hydrogen carbonate, hartshorn, or powdered baking ammonia, is the bicarbonate salt of ammonia.

Ammonium bicarbonate is formed as shown below, or by passing carbon dioxide through a solution of the normal compound, when it is deposited as a white powder, which has no smell and is only slightly soluble in water. The aqueous solution of this salt liberates carbon dioxide on exposure to air or on heating, and becomes alkaline in reaction. The aqueous solutions of all the carbonates when boiled undergo decomposition with liberation of carbon dioxide and the substance with which the carbonate ion reacted to form the bicarbonate, in this case, ammonia:

NH₄HCO₃ → NH₃ + H₂O + CO₂

Properties

At room temperature, ammonium bicarbonate is a white, crystalline powder with a slight odour of ammonia that can dissolve in water to give a mildly alkaline solution. It is however insoluble in acetone and alcohols. Ammonium bicarbonate decomposes at 36 to 60 °C into ammonia, carbon dioxide and water vapor in an endothermic process (as it is with many ammonium salts) and so causes a drop in the temperature of the water. When reacted with acids, carbon dioxide is produced, while reactions with alkalis give ammonia.

Uses

Ammonium bicarbonate is used in the food industry as a raising agent (e.g., for gingerbread, digestive biscuit or Chinese youtiao). It was commonly used in the home before baking soda was made widely available. Many baking cookbooks (especially from Scandinavian countries) may still refer to it as hartshorn or hornsalt ^[1][2]. In many cases it may be substituted with baking soda.^[3]

It is commonly used as an inexpensive nitrogen fertilizer in China, but is now being phased out in favor of urea because of its relatively low quality and instability. This compound is used as a component in the production of fire-extinguishing compounds, pharmaceuticals, dyes, pigments and it is also a basic fertilizer being a source of ammonia. Ammonium bicarbonate is still widely used in the plastic and rubber industry, in the manufacture of ceramics, in chrome leather tanning and for the synthesis of catalysts.^{[citation needed]}

Some websites suggest substituting baking powder for ammonium bicarbonate, instead of baking soda.

Reactions

Ammonium bicarbonate decomposes to carbon dioxide, ammonia, and water vapor on heating; it liberates CO2 when treated with dilute mineral acids:

NH₄HCO₃ + HCl → NH₄Cl + CO₂ + H₂O

It reacts with sulfates of alkaline-earth metals precipitating out their carbonates:

CaSO₄ + 2 NH₄HCO₃ → CaCO₃ + (NH₄)₂SO₄ + CO₂ + H₂O

Safety

Ammonium bicarbonate is an irritant to the skin, eyes and respiratory system. Ammonium bicarbonate from China used to make cookies was found to be contaminated with melamine, and imports banned in Malaysia in the 2008 Chinese milk scandal.

References

1. ^ "separation of hornsalt". http://www.studenttorget.no/index.php?artikkelid=849. 
2. ^ ""separation of hornsalt" translated into English". http://www.tranexp.com:2000/InterTran?type=url&url=http%3A%2F%2Fwww.studenttorget.no%2Findex.php%3Fartikkelid%3D849&text=&from=nor&to=eng. 
3. ^ "What is hartshorn?". http://www.ochef.com/539.htm. Retrieved 2007-03-19.