Ammonium Carbonate

Ammonium carbonate is a chemical compound with the formula ([NH_4]_2CO_3). It is an ammonium salt derived from carbonic acid and is comprised of ammonium cations ((NH_4^+)) and carbonate anions ((CO_3^{2-})). Ammonium carbonate is a white crystalline solid that is notable for its use in a variety of applications, particularly in the food and chemical industries.

Historical Context and Production

Historically, ammonium carbonate was known as hartshorn, made by the sublimation of ground deer horn. Today, it is commonly referred to as baker's ammonia. The modern preparation involves the sublimation of a mixture of ammonium sulfate and calcium carbonate. This process yields ammonium carbonate as a white powder or a hard, white, or translucent mass.

Applications

Baking and Leavening Agent

Ammonium carbonate serves as a leavening agent in various traditional recipes, particularly in those from northern Europe and Scandinavia such as Amerikaner, Speculoos, Tunnbröd, and Lebkuchen. It was a precursor to the modern baking powder, providing a similar function by releasing carbon dioxide to aerate and increase the volume of dough and batters.

Medicinal and Household Uses

Ammonium carbonate is the main ingredient in smelling salts, which have been used historically to revive those who have fainted or are feeling faint. In Canada, it is an active component in Buckley's cough syrup, where it is intended to relieve symptoms of bronchitis. Additionally, it can act as an emetic.

Chemical Properties and Reactions

Upon exposure to air, ammonium carbonate decomposes, releasing ammonia gas and reverting to ammonium bicarbonate. This decomposition is what gives ammonium carbonate its characteristic smell and is the basis for its use in smelling salts and other applications.

Relationship to Other Compounds

Ammonium carbonate is related chemically to ammonium bicarbonate and ammonium carbamate. These compounds can exist in equilibrium in aqueous solutions, influenced by temperature and pressure conditions.