Ammonium Carbonate: Formula, Properties, Uses and Baker’s Ammonia

Ammonium carbonate formula and names

The formula of ammonium carbonate is (NH₄)₂CO₃: two ammonium ions, NH₄⁺, and one carbonate ion, CO₃²⁻. Its molar mass is 96.09 g/mol. In bakeries it is better known by older names such as baker’s ammonia and hartshorn, and in food-additive lists it carries the number E503(i).

The molar mass follows from the atomic masses: 2 × 14.007 (nitrogen) + 8 × 1.008 (hydrogen) + 12.011 (carbon) + 3 × 15.999 (oxygen) = 96.086, which rounds to 96.09 g/mol. The US tariff lists ammonium carbonates under 2836.99.30 (“commercial ammonium carbonate and other ammonium carbonates”); check the full tariff line for your own country with your customs broker.

Why commercial ammonium carbonate is a mixture

Pure ammonium carbonate is not stable at room temperature. A 2025 technical review for the USDA National Organic Program notes that it is only stable at freezing temperatures and changes into ammonium bicarbonate, and that it forms only under carefully controlled conditions that are hard to achieve in production plants.

What is sold as ammonium carbonate is therefore a mixture. The US Food and Drug Administration defines food-grade ammonium carbonate (CAS 8000-73-5) as a mixture of ammonium bicarbonate (NH₄HCO₃) and ammonium carbamate (NH₂COONH₄), and the USDA review says commercial food products are usually equal mixtures of the two. That is why you will see different CAS numbers and assay bases on different suppliers’ certificates.

Solubility figures are from the tables in the USDA review. Ammonium bicarbonate is the more stable of the two and is widely sold on its own, also as a leavening agent.

Appearance, smell and what heat does

Ammonium carbonate is a white powder, colourless crystals or a hard, white or translucent mass with a strong smell of ammonia. It dissolves readily in water and does not burn. NOAA’s CAMEO Chemicals database gives a specific gravity of about 1.5, so it is denser than water.

The ammonia smell is the clue to its behaviour: it slowly breaks down even at room temperature, and on heating it decomposes into ammonia, carbon dioxide and water. The USDA review notes that ammonium carbonates degrade above about 60 °C, and the Food Chemicals Codex describes the bicarbonate volatilising rapidly at 60 °C or above.

(NH₄)₂CO₃ → 2 NH₃ + CO₂ + H₂O

Because every product of this reaction is a gas or water, ammonium carbonate leaves no solid residue when it decomposes. That property is what makes it useful in baking.

What ammonium carbonate is used for

• Leavening. The gases released in the oven raise the dough. The USDA review describes ammonium carbonates as leavening agents for low-moisture baked goods such as dry cookies and crackers.
• pH control in food. The FDA affirms food-grade ammonium carbonate as generally recognised as safe (21 CFR 184.1137) for use as a leavening agent and a pH control agent, at levels set by good manufacturing practice.
• Other food uses. The USDA review lists its use as a nitrogen source for yeast cultures and as an optional neutralising additive in cacao products.
• Smelling salts. The ammonia it gives off irritates the nose and airways, which is the basis of traditional smelling salts.
• Chemicals and pharmaceuticals. CAMEO lists its use in making other ammonium compounds, in pharmaceuticals and in food processing.

Commercially it is made from ammonia and carbon dioxide in water, a reaction that gives off heat. The FDA regulation describes its preparation by subliming a mixture of ammonium sulphate and calcium carbonate.

Handling and storage

According to CAMEO, breathing the dust or fumes irritates the nose and throat, contact irritates the eyes and skin, and swallowing it may cause stomach irritation. In a fire it decomposes, non-explosively, to toxic ammonia gas. It also decomposes sodium hypochlorite (bleach) within seconds, so keep the two apart.

Because it loses ammonia over time, store it in tightly closed containers in a cool, dry, well-ventilated place, away from heat and acids, and open containers in a ventilated area. CAMEO lists no UN number for it; confirm the transport classification on the current safety data sheet (SDS) for the grade you buy.

Questions to ask a supplier

• Is the material food grade (Food Chemicals Codex or E503(i) specification) or a technical grade?
• Which CAS number and composition does the Certificate of Analysis state, and on what basis is the assay expressed?
• How is it packed to limit loss of ammonia, and what storage temperature and shelf life do you recommend?
• Can you share the current SDS and the transport classification for my shipment?
• Do you need ammonium carbonate, or would ammonium bicarbonate suit your process better?

Enquire with Scapex Exports

Scapex Exports is an exporter and supplier of industrial and fine chemicals from India. Related products in our catalogue include ammonium carbonate, ammonium bicarbonate and food-grade sodium bicarbonate. Each product page links to its COA and MSDS, and our guide to ammonium hydroxide covers another common ammonium chemical.

Tell us the grade, the specification you need, the quantity, packing and destination port, and we will reply with a quotation.

Frequently asked questions

Sources: NOAA CAMEO Chemicals, ammonium carbonate; US eCFR, 21 CFR 184.1137 Ammonium carbonate; OMRI for the USDA National Organic Program, Technical Evaluation Report: Ammonium Bicarbonate and Carbonate (January 2025); US Harmonized Tariff Schedule, subheading 2836.99.30.