Ammonium bicarbonate (NH₄HCO₃) is an inorganic compound with a wide range of applications. Here's a breakdown of its properties, uses, and safety considerations:
Chemical and Physical Properties:
- Appearance: White crystalline solid or powder.
- Odor: Faint smell of ammonia.
- Solubility: Readily soluble in water. Insoluble in acetone, ethanol, and other organic solvents.
- Decomposition: Thermally unstable; decomposes above approximately 36-60°C into ammonia (NH₃), carbon dioxide (CO₂), and water (H₂O). This decomposition is endothermic, meaning it absorbs heat.
- Molar Mass: Approximately 79.06 g/mol.
- pH: Aqueous solutions are mildly alkaline (around 7.8).
Uses:
- Food Industry:
- Leavening Agent: Primarily used in flat baked goods like cookies and crackers. It releases carbon dioxide and ammonia gases during baking, creating a light and porous texture. The ammonia smell dissipates during baking.
- Acidity Regulator: Can be used to adjust the pH in food products.
- Stabilizing Agent: Helps maintain the desired physicochemical properties and color in some foods.
- Agriculture:
- Fertilizer: Used as an inexpensive source of nitrogen, particularly in China. However, it's being phased out in favor of urea due to stability issues.
- Soil pH Adjustment: Can slightly increase the pH of acidic soils.
- Animal Feed: Acts as a buffering agent in animal feed, especially for ruminants, to regulate pH in the digestive tract.
- Cosmetics Industry:
- Buffering Agent: Helps stabilize the pH of cosmetic formulations.
- Texturizing Agent: Can improve the texture and stability of products like mousse.
- Foaming Agent: Used in hair mousse and facial cleansers for a light and airy texture.
- Odor Neutralizer: Used in some deodorants.
- Mild Cleansing/Exfoliating Agent: May be found in some personal care products.
- Cleaning Industry:
- Component in Cleaners: Used in oven cleaners to remove grease, all-purpose cleaners as a mild abrasive, and carpet cleaners for stain removal.
- Descaling Agent: Can help remove mineral deposits.
- Window Cleaner: Used in some formulations.
- Plastics and Rubber Industry:
- Blowing Agent: Used to create foamed plastics and foam rubber, resulting in lightweight materials for various applications (automotive, construction, packaging, sports shoes, seals, insulation).
- Other Industrial Uses:
- Production of Fire-Extinguishing Compounds: Releases non-flammable gases upon heating.
- Pharmaceuticals: Used in some medications, including as an expectorant in cough syrups and to produce ammonium salts.
- Dyes and Pigments: Used in the manufacturing process.
- Ceramics: Used in the manufacturing of ceramics.
- Leather Tanning: Used in chrome leather tanning.
- Synthesis of Catalysts: Used in the production of catalysts.
- pH Buffer in Chemical Purification: Used to make solutions slightly alkaline, for example, in high-performance liquid chromatography (HPLC). Its volatility allows for easy removal by freeze-drying.
- Attractant for Insects: Used to trap certain insects like the walnut husk fly.
- Mining: Component of explosives and used for dust control.
