Ammonium Bicarbonate

Ammonium bicarbonate is an inorganic compound with the formula (NH 4 )HCO 3 , simplified to NH 5 CO 3 . The complex has several names, reflecting its long history. Chemically speaking, it is the bicarbonate salt of the ammonium ion . It is a colorless solid that readily degrades into carbon dioxide, water and ammonia.

Ammonium Bicarbonate

chemical formula = NH 4 HCO 3
molar mass = 79.056 g/mol
density = 1.586 g/ cm3
Melting point = 41.9 °C (107.4 °F; 315.0 K) decomposed
Solubility in water = 11.9 g/100 mL (0 °C)
21.6 g/100 mL (20 °C)
24.8 g/100 mL (25 °C)
36.6 g/100 mL (40 °C)
solubility = insoluble in methanol


Ammonium bicarbonate is produced by combining carbon dioxide and ammonia:

CO 2 + NH 3 + H 2 O → (NH 4 ) HCO 3

Since ammonium bicarbonate is thermally unstable, the reaction solution is kept cold, which allows precipitation of the product as a white solid. About 100,000 tons were produced this way in 1997. [3]

Ammonia gas is passed into a strong aqueous solution of sesquicarbonate ((NH 4 ) HCO 3 , (NH 4 ) 2 CO 3 , and a 2:1:1 mixture of H 2 O ) to form normal ammonium carbonate ((NH 4 ) ) ) 2 CO 3 ), which can be obtained in the crystalline state from a solution prepared at about 30 °C. When exposed to air, this compound releases ammonia and reverts to ammonium bicarbonate.

Hartshorne’s salt

Compositions containing ammonium carbonate have been known for a long time. They were once produced commercially, previously known as year’s volatiles or Hartshorne’s salt. It was obtained by dry distillation of nitrogenous organic matter such as hair, horn, leather. In addition to ammonium bicarbonate, this material includes ammonium carbamate (NH 4 CO 2 NH 2 ), and ammonium carbonate ((NH 4 ) 2 CO 3 ). It is sometimes called ammonium sesquicarbonate. It has a strong ammoniacal odor, and upon digestion with alcohol, the carbamate dissolves, leaving a residue of ammonium bicarbonate. [3]

A similar decomposition occurs when sesquicarbonate is exposed to air.


Ammonium bicarbonate is used in the food industry as a leavening agent for flat baked goods, such as cookies and crackers. It was commonly used in the home before modern baking powder was available. Many baking cookbooks, especially from Scandinavian countries, may still refer to it as hartshorne or hornsalt, [4] [5]While it is known as “Hirvensarvisuola” in Finnish, “Hjortteksalt” in Norwegian, “Hjortteksalt”, “Hjorthornsalt” in Danish. “In Swedish, and in German “Hirshornsalz” (lit., “salt of the horn of the heart”). Although there is a slight smell of ammonia during baking, it dissipates quickly, leaving no taste. Its It is used, for example, in Swedish “Dromer” biscuits and Danish “Brunkeger” Christmas biscuits, and in German Lebkuchen. In many cases it can be replaced with baking soda or baking powder, or a combination of both, depending on the recipe structure. and depends on the requirements of the yeast. [6]Compared to baking soda or potash, Hartshorne has the advantage of producing more gas for the same amount of agent and leaving no salty or soapy taste in the finished product, as it completely decomposes into water and gaseous products. which evaporates during baking. It cannot be used for moist, heavy baked goods, such as normal breads or cakes, as some of the ammonia will be trapped inside and create an unpleasant taste. It is assigned the E number E503 for use as a food additive in the European Union.

It is commonly used in China as an inexpensive nitrogen fertilizer, but is now being phased out in favor of urea for quality and stability. This compound is used as an ingredient in the production of fire extinguishing compounds, pharmaceuticals, dyes, dyes, and is also a basic fertilizer, being a source of ammonia. Ammonium bicarbonate is still widely used in the plastics and rubber industry, in the manufacture of ceramics, in chrome tanning, and for the synthesis of catalysts.

It is also used for buffering solutions to make them slightly alkaline during chemical purification, such as in high performance liquid chromatography. Because it completely decomposes into volatile compounds, it allows rapid recovery of the compound of interest by freeze-drying. Ammonium bicarbonate is also a major component of the cough syrup “Senega and Ammonia”.


It dissolves in water to give a slightly alkaline solution. It is insoluble in acetone and alcohol.

Ammonium bicarbonate decomposes into ammonia, carbon dioxide and water above about 36 °C in an endothermic process and therefore causes a drop in water temperature:

NH 4 HCO 3 → NH 3 + H 2 O + CO 2 .

When treated with acids, ammonium salts are also formed:

NH 4 HCO 3 + HCl → NH 4 Cl + CO 2 + H 2 O.

Reaction with alkali produces ammonia.

It reacts with sulfates of alkaline-earth metals to precipitate their carbonates:

CaSO 4 + 2 NH 4 HCO 3 → CaCO 3 + (NH 4 ) 2 SO 4 + CO 2 + H 2 O।

It also reacts with alkali metal halides, giving alkali metal bicarbonate and ammonium halide:

NH 4 HCO 3 + NaCl → NH 4 Cl + NaHCO 3 ;

NH 4 HCO 3 + KI → NH 4 I + KHCO 3 ;

NH 4 HCO 3 + NaBr → NH 4 Br + NaHCO 3

natural phenomena

The compound occurs in nature as teschemakerite, an extremely rare mineral. 


Ammonium bicarbonate is an irritant to the skin, eyes and respiratory system. Short-term health effects can occur soon after or shortly after exposure to ammonium bicarbonate. Inhaling ammonium bicarbonate can irritate the nose, throat, and lungs causing cough, wheezing and/or shortness of breath. With repeated exposure, bronchitis can develop with cough, and/or shortness of breath. Health effects can occur some time after exposure to ammonium bicarbonate and can last for months or years.

Where possible, operations should be enclosed and the use of local exhaust ventilation at the site of chemical release is recommended. If local exhaust ventilation or enclosure is not used, respirators are necessary. Wear protective work clothing and change clothing and wash thoroughly immediately after exposure to ammonium bicarbonate. [8]

Ammonium bicarbonate used to make cookies from China was found to be contaminated with melamine, and imports were banned in Malaysia following the 2008 Chinese milk scandal.