Name: Sodium Carbonate
CAS No: Sodium carbonate anhydrous [497-19-8], Sodium carbonate monohydrate [5968-11-6], Sodium carbonate decahydrate [6132-02-1]
BP: Anhydrous Sodium Carbonate JP: Dried Sodium Carbonate PhEur: Sodium Carbonate, Anhydrous USP-NF: Sodium Carbonate
Bisodium carbonate; calcined soda; carbonic acid disodium salt; cenzias de soda; crystol carbonate; disodium carbonate; E500; natrii carbonas anhydricus; soda ash; soda calcined.
Sodium carbonate anhydrous [497-19-8], Sodium carbonate monohydrate [5968-11-6], Sodium carbonate decahydrate [6132-02-1]
Na2CO3 105.99 Na2CO3H2O 124.0 Na2CO310H2O 286.1
See Section 4.
Sodium carbonate is used as an alkalizing agent in injectable, ophthalmic, oral, and rectal formulations. In effervescent tablets or granules, sodium carbonate is used in combination with an acid, typically citric acid or tartaric acid.(1) When the tablets or granules come into contact with water, an acid– base reaction occurs in which carbon dioxide gas is produced and the product disintegrates.(2) Raw materials with low moisture contents are required to prevent the early triggering of the effervescent reaction.(2) As an alkalizing agent, concentrations of sodium carbonate between 2% and 5% w/w are used in compressed tablet formulations.(1,3) As an effervescent agent, concentrations of sodium carbonate up to 10% w/w can be used.(2) Therapeutically, sodium carbonate is also used as an oral antacid.(4)
Sodium carbonate is a white, almost white, or colorless inorganic salt, produced as crystalline powder or granules. It is hygroscopic and odorless with an alkaline taste
See Table I.
Acidity/alkalinity Strongly alkaline; pH = 11.4 (1% w/v aqueous solution at 258C).(5) Hygroscopicity One mole of sodium carbonate will gradually absorb 1 mole of water (approximately 15%) on exposure to air. Melting point 8518C Refractive index nD 20 = 1.3352 at 1.0% w/w solution; 1.3440 at 5.0% w/w solution; 1.3547 for 10.0% w/w solution.(6) Solubility Freely soluble in water, with solubility initially increasing with temperature and then settling at 30.8% w/w above 808C(5) (see Figure 1). Soluble in glycerin; practically insoluble in ethanol (95%). Specific gravity 2.53
Sodium carbonate converts to the monohydrate form when in contact with water and produces heat. It begins to lose carbon dioxide at temperatures above 4008C(7) and decomposes before boiling. Store in airtight containers.
Sodium carbonate decomposes when in contact with acids in the presence of water to produce carbon dioxide and effervescence. It may react violently with aluminum, phosphorous pentoxide, sulfuric acid, fluorine, and lithium.
Sodium carbonate is produced by the ammonia-soda process, also known as the Solvay process.(7)
Sodium carbonate is used in injectable, oral, and rectal pharmaceutical formulations. The pure form of sodium carbonate is mildly toxic by ingestion, moderately toxic by inhalation and SC routes, and very toxic by the IP route. It is irritating to the skin and eyes. Dust and vapors of sodium carbonate may irritate mucous membranes, causing coughing and shortness of breath. It also has experimental reproductive effects. Sodium carbonate can migrate to food from packaging materials. When used as an excipient or antacid, sodium carbonate is generally regarded as a nontoxic and nonirritating material. LD50 (mouse, IP): 0.12 g/kg(8) LD50 (mouse, SC): 2.21 g/kg LD50 (rat, oral): 4.09 g/kg
Observe normal precautions appropriate to the circumstances and quantity of the material handled. When heated to decomposition it emits toxic fumes of sodium oxide. Eye protection and gloves are recommended. Respiratory protection is also recommended if inhalable dust is present
GRAS listed. Accepted for use as a food additive in Europe. Included in the FDA Inactive Ingredients Database (injections; ophthalmic solution; oral capsules and tablets; rectal suspensions). Included in the Canadian List of Acceptable Non-medicinal Ingredients. Included in parenteral (powder for solution for injection) and nonparenteral medicines (oral effervescent tablets, soluble tablets, granules, lozenges, chewing gums) licensed in the UK. USP32–NF27 allows either the anhydrous or the monohydrate form.
Sodium bicarbonate; sodium carbonate decahydrate; sodium carbonate monohydrate. Sodium carbonate decahydrate Empirical formula Na2CO310H2O Molecular weight 286.1 CAS number [6132-02-1] Description Colorless, transparent, or white crystals or powder. Solubility Freely soluble in water; practically insoluble in ethanol (95%).Comments Listed in PhEur 6.0 and JP XV. Used in alkaline baths.(4) Sodium carbonate monohydrate Empirical formula Na2CO3H2O Molecular weight 124.0 CAS number [5968-11-6] Description Colorless or white crystals or granules. Solubility Soluble in 3 parts water, 1.8 parts boiling water, or 7 parts glycerin. Practically insoluble in ethanol (95%). Dries out in warm dry air or above 508C, and converts to anhydrous form above 1008C. Comments Listed in PhEur 6.0 and USP32–NF27. Commonly used in antacid preparations and as a reagent.(4)
Sodium carbonate is more stable in effervescent formulations than sodium bicarbonate,(3) but is less effective as an effervescent agent and therefore sodium bicarbonate is most commonly used in effervescent formulations.(2) Sodium carbonate can be added to these formulations as a stabilizing agent (up to 10% w/w) as it absorbs moisture, preventing early effervescent reactions.(2) This effect is exploited in Effer-Soda, in which a sodium bicarbonate core is protected by a surface layer of sodium carbonate, equivalent to 8–12% w/w.(9) The technical grade of sodium carbonate anhydrous (approximately 99% purity) is known as soda ash. A specification for sodium carbonate is contained in the Food Chemicals Codex (FCC).(10) The EINECS number for sodium carbonate is 207-838-8. The PubChem Compound ID (CID) for sodium carbonate is 10340.