Ammonium carbonate will slowly decompose to give off ammonia, carbon dioxide and water vapors. The reaction occurs faster at higher temperatures:
- (NH4)HCO3 → NH3 + H2O + CO2
Ammonium carbamate is another potential by-product of decomposition.
When treated with acids, it releases carbon dioxide:
- (NH4)HCO3 + HCl → NH4Cl + H2O + CO2
It also reacts with alkali metal halides, giving ammonium halide and alkali metal bicarbonate:
- NH4HCO3 + LiCl → NH4Cl + LiHCO3
- NH4HCO3 + NaBr → NH4Br + NaHCO3
- NH4HCO3 + KI → NH4I + KHCO3
Ammonium bicarbonate is a white salt, soluble in water, but insoluble in organic solvents like methanol, diethyl ether. It will slowly decompose over time, even at low temperatures, releasing ammonia gas, which gives the salt a strong smell. The decomposition occurs faster at high temperatures.
Ammonium bicarbonate can be bought from food stores as "smelly" baking powder, either very pure or mixed with other carbonates, such as sodium bicarbonate or magnesium carbonate. Sometimes it's referred to as simply "ammonium", usually the label name.
Ammonium bicarbonate can be made by bubbling an excess of carbon dioxide gas through a cold solution of ammonia.
- CO2 + NH3 + H2O → (NH4)HCO3
Alternatively, it can be made by heating a mixture of ammonium nitrate, sodium bicarbonate or carbonate, and water in one container, and channeling the generated gases into a chilled empty container, where it will crystallize on the walls.
- Ammonium carbonate synthesis
- Generate ammonia gas
- Synthesize any other ammonium salt. Both forms of Hartshorn are very convenient precursors to all salts of ammonium.
Ammonium bicarbonate gives off ammonia fumes, which are irritating and toxic if they build up in a closed environment.
Ammonium bicarbonate is best stored in closed containers and kept in cold places. To limit the ammonia gas released, you can store the ammonium bicarbonate in a resealable bag, which in turn can be placed in a container.
Ammonium bicarbonate can be neutralized with any acid and safely dumped in both soil and down the drain, as it poses no danger to the environment.