Article: Ammonium bicarbonate

Ammonium bicarbonate
Systematic name	Ammonium bicarbonate
Other names	Ammonium Hydrogen Carbonate, Acid Ammonium Carbonate, Monoammonium Carbonate, Carbonic Acid Monoammonium Salt
Molecular formula	NH4HCO3
Molar mass	79.06 g/mol
CAS number	[1066-33-7]
Density	1.586 g/cm3
Solubility (water)	Soluble (17.4% at 20 °C)
Melting point	106 °C
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Ammonium bicarbonate (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 above and also 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 ammonia and of carbon dioxide:

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 was used in the food industry as a raising agent (e.g. for gingerbread or Chinese youtiao) before the introduction of baking soda. 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 manifacture of ceramics, in chrome leather tanning and for the synthesis of catalysts.

Safety

Ammonium bicarbonate is irritant to the skin, eyes and respiratory system.