Sodium carbonate
[CAS# 497-19-8]

Identification

• Classification: API >> Water, electrolyte and acid-base balance regulator >> Acid-base balance regulator
• Name: Sodium carbonate
• Synonyms: disodium carbonate
• Molecular Formula: Na₂CO₃
• Molecular Weight: 105.99
• CAS Registry Number: 497-19-8 (7542-12-3)
• EC Number: 207-838-8
• SMILES: C(=O)([O-])[O-].[Na+].[Na+]

Properties

• Density: 2.53 g/mL
• Melting point: 851 ºC
• Boiling point: 1600 ºC
• Water solubility: 22 g/100 mL (20 ºC)

Safety Data

• Hazard Symbols: GHS07 Warning
• Hazard Statements: H319
• Precautionary Statements: P264+P265-P280-P305+P351+P338-P337+P317

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Eye irritation	Eye Irrit.	2	H319
Specific target organ toxicity - single exposure	STOT SE	3	H335
Acute toxicity	Acute Tox.	4	H332
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	4	H312
Specific target organ toxicity - repeated exposure	STOT RE	2	H373
Acute toxicity	Acute Tox.	4	H302
Skin irritation	Skin Irrit.	2	H315

Discovory and Applicatios

Sodium carbonate, with the chemical formula Na₂CO₃, is a white, water-soluble inorganic compound commonly known as soda ash or washing soda. It has been known and utilized for centuries, with historical records indicating its use by ancient Egyptians who extracted it from the ashes of native plants growing in sodium-rich soils near dry lake beds. These early sources of sodium carbonate were mixtures containing other sodium salts and were collectively referred to as natron.

In the 18th century, large-scale production of sodium carbonate became essential due to its demand in glass making, soap production, and textile processing. The first industrial method for synthesizing sodium carbonate was developed by Nicolas Leblanc in the late 1700s. Known as the Leblanc process, it involved the reaction of sodium chloride (common salt) with sulfuric acid, followed by roasting with limestone and coal. Although this method provided a reliable source of soda ash, it generated large quantities of harmful waste.

A more efficient and environmentally friendly process, the Solvay process, was introduced by Ernest Solvay in the 1860s and remains the dominant method of sodium carbonate production today. In the Solvay process, sodium chloride reacts with ammonia and carbon dioxide in water to precipitate sodium bicarbonate, which is then calcined to form sodium carbonate. This process significantly reduced the cost and environmental impact of production and facilitated the widespread industrial use of sodium carbonate.

Sodium carbonate has a wide range of applications in both industrial and household contexts. In glass manufacturing, it serves as a flux to lower the melting point of silica, facilitating the production of soda-lime glass. In this application, sodium carbonate reacts with silica and calcium carbonate to form a stable, clear material widely used for bottles, windows, and other glass products.

In the detergent and cleaning products industry, sodium carbonate is used to soften water by precipitating calcium and magnesium ions, thereby enhancing the effectiveness of soaps and surfactants. Its alkalinity also helps to break down grease and remove stains, making it a key ingredient in many household and industrial cleaning agents.

In chemical laboratories and industrial processes, sodium carbonate serves as a buffering agent and a basic reagent. It is used to neutralize acids and to maintain stable pH conditions in various reactions. In metallurgy, it is employed in ore processing, particularly in the extraction of alumina from bauxite. Additionally, sodium carbonate is involved in the synthesis of sodium-containing compounds and serves as a feedstock in the production of sodium silicates, sodium phosphates, and other chemical intermediates.

In the food industry, sodium carbonate is approved as a food additive and designated with the code E500. It acts as a leavening agent in baking and a pH regulator in food processing. It is also used in the preparation of ramen noodles and other alkali-treated foods to enhance texture and color.

Environmental and safety considerations are relatively moderate for sodium carbonate. It is generally regarded as non-toxic and environmentally benign when used appropriately. However, its strong alkalinity can cause irritation to the skin and eyes upon direct contact, and inhalation of its dust may lead to respiratory discomfort. Proper handling procedures, such as the use of protective gloves and masks in industrial settings, help mitigate these risks.

Natural sources of sodium carbonate include deposits of trona, a mineral composed primarily of sodium carbonate, sodium bicarbonate, and water. Large trona deposits are found in regions such as the Green River Basin in Wyoming, USA. These deposits are mined and processed to extract high-purity sodium carbonate for commercial use.

In conclusion, sodium carbonate is a well-established and indispensable compound with applications spanning glass making, chemical manufacturing, water treatment, food processing, and household cleaning. Its discovery, refinement through the Solvay process, and ongoing industrial significance reflect its central role in both historical and modern chemistry.

References

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