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
Ammonium bicarbonate 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.
Some websites suggest substituting baking powder for ammonium bicarbonate, instead of baking soda.
| Product name | Ammonium bicarbonate |
| 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) |
| Solubility | insoluble in methanol |
| MSDS | ICSC 1333 |
| Flash point | Non-flammable |
| Other cations | Sodium bicarbonate |