Ammonium bicarbonate (also known as ammonium hydrogen carbonate) is a mildly basic inorganic compound with the formula (NH4)HCO3. It is a colourless, crystalline solid with the odour of ammonia. It is soluble in water, but insoluble in most organic solvents including ethanol, carbon disulphide and concentrated ammonia. It is volatile in solution and degrades readily into ammonia and carbon dioxide in an endothermic reaction. This property makes it useful as a leavening agent in baked products such as cakes and biscuits, and as a buffer in applications such as lyophilization and matrix assisted laser desorption. It is also a commonly used reagent in many industrial and research procedures.
Handling and Storage
Do not breathe dust. Wear suitable protective clothing. In case of insufficient ventilation, wear suitable respiratory
equipment. If you feel unwell, seek medical attention and show the label when possible. Avoid contact with skin
- Storage: Keep container tightly closed. Keep container in a cool, well-ventilated area.
Measures in Case of Accidents
Remove to fresh air. If not breathing, give artificial respiration. If breath areaing is difficult, give oxygen. Call a physician.
DO NOT INDUCE VOMITING. Give large quantities of water. Never give anything by mouth to an unconscious person. Call a physician immediately.
- Skin Contact:
Immediately flush skin with plenty of soap and water for at least 15 minutes while removing contaminated clothing and shoes. Get medical attention. Wash clothing before reuse. Thoroughly clean shoes before reuse.
- Eye Contact:
Immediately flush eyes with plenty of water for at least 15 minutes, lifting lower and upper eyelids occasionally. Get medical attention immediately.
Ammonium Bicarbonate irritates the skin, eyes, and the respiratory system, and short-term health effects can appear immediately or shortly after exposure. Inhalation can lead to coughing, wheezing, and/or shortness of breath due to irritation of the nose, throat, and lungs. Chronic exposure may lead to bronchitis along with the short-term effects. The health effects can last for months or years.
Operations involving ammonium bicarbonate should be carried out in enclosed conditions with local exhaust ventilation as much as possible. If not, respirators must be used, and protective work clothing is necessary. After exposure to ammonium bicarbonate, change clothes and wash them thoroughly.
Ammonium bicarbonate is produced by passing carbon dioxide gas countercurrently through a descending stream of aqueous ammonia (ammonium hydroxide), usually in either a packed tower or an absorption column. Carbon dioxide gets absorbed into the liquid stream of ammonia and water, and reacts to form ammonium bicarbonate as below:
CO2 + NH3 + H2O → (NH4)HCO3
Since the reaction is exothermic and ammonium bicarbonate is unstable, the system, especially the lower portion of the tower, is generally maintained at a lower temperature.
Once the solution is sufficiently saturated, the ammonium bicarbonate crystallizes as a white solid. These crystals are separated from the solution by precipitation, followed by centrifugal separation and washing. The crystals are then dried using air at 50°C.
Upon refining, the crystals are dissolved in water then recrystallized by adding ethanol.