Sodium carbonate

• BPAnhydrous Sodium Carbonate
• JPDried Sodium Carbonate
• Ph. Eur.Sodium Carbonate, Anhydrous
• Ph. Eur.Sodium Carbonate Monohydrate
• Ph. Eur.Sodium Carbonate Decahydrate
• USP–NFSodium Carbonate

Calcined soda; carbonic acid disodium salt; disodium carbonate; natrii carbonas anhydricus; soda ash; washing soda (decahydrate); E500(i)

Carbonic acid disodium salt · [497-19-8]

UNII 45P3261C7T · PubChem CID 10340

Na2CO3 (anhydrous); Na2CO3·H2O (monohydrate); Na2CO3·10H2O (decahydrate) · 105.99 (anhydrous); 124.00 (monohydrate); 286.14 (decahydrate)

pH adjuster, buffering agent

Typical concentrations: — · Dosage forms: Solid

Sodium carbonate is used as an alkalising agent and pH adjuster in injections, ophthalmic, oral and topical preparations, and as a buffer component. In effervescent tablets and granules it is used together with sodium bicarbonate, where it can act as a moisture scavenger and improve stability. It is also used to form soluble salts of acidic drugs in situ and in some cleansing and dental products.

The anhydrous form is an odourless, white, hygroscopic powder or granules with an alkaline taste. The monohydrate is a white crystalline powder, and the decahydrate occurs as colourless, efflorescent crystals.

Melting point

851 °C (anhydrous)

pH

strongly alkaline; about 11.5 for a 1% w/v aqueous solution

Solubility

freely soluble in water (more so in hot water); practically insoluble in ethanol

Hygroscopicity

the anhydrous form absorbs moisture and carbon dioxide from the air; the decahydrate loses water in dry air

Chemically stable. The anhydrous material slowly absorbs moisture from humid air, forming the monohydrate. Store in an airtight container in a dry place.

Reacts with acids and acidic salts with effervescence. Incompatible with calcium and other polyvalent metal salts (precipitation of carbonates) and with aluminium. Its high pH may degrade alkali-sensitive drugs, such as esters, and precipitate weak bases.

Produced by the ammonia–soda (Solvay) process, in which sodium bicarbonate precipitated from brine is calcined to the carbonate, or from natural deposits of trona. The hydrates are obtained by crystallisation from aqueous solution.

At the low concentrations used to adjust pH it is regarded as non-toxic. Concentrated solutions and the solid are irritant or corrosive to skin, eyes and mucous membranes, and ingestion of large amounts can cause gastrointestinal irritation.

Observe normal precautions for the quantity handled. The powder is irritant to the eyes and respiratory tract; wear eye protection, gloves and a dust mask, and add the solid slowly to water.

GRAS listed. Accepted as a food additive in Europe (E500). Included in the FDA Inactive Ingredient Database (injections, ophthalmic, oral and topical preparations) and in medicines licensed in Europe.

Potassium carbonate; sodium bicarbonate; sodium sesquicarbonate.

Specify the hydrate used, as the water content (and therefore the amount needed) differs widely: the decahydrate contains about 63% water. Anhydrous sodium carbonate is the usual choice in effervescent and moisture-sensitive formulations.