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Sodium carbonate

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– Sodium carbonate exists in three hydrates (decahydrate, heptahydrate, monohydrate) and as an anhydrous salt.
– Anhydrous sodium carbonate is obtained by heating the hydrates.
– Different hydrates form at specific temperature ranges.
– Other hydrates with varying water content have been reported.

**Washing Soda**:
– Sodium carbonate decahydrate, known as washing soda, contains 10 molecules of water.
– Obtained by dissolving soda ash in water and crystallizing.
– It is one of the few metal carbonates soluble in water.

– Used in cleansing agents, dry soap powders, glass, soap, and paper manufacturing.
– Lowers water hardness and aids in producing sodium compounds like borax.

**Glass Manufacture**:
– Acts as a flux for silica, reducing the melting point.
– Added to soda–lime glass production to make glass insoluble.

– **Mining**: Trona mined in the US, large deposits near Green River, Wyoming, important reserves in Turkey.
– **Barilla and Kelp**: Historical sources from halophyte plants and seaweed.
– **Leblanc Process**: Developed in 1792 for sodium carbonate production, dominated until late 1880s.
– **Hou’s Process**: Developed in the 1930s, coupled to the Haber process for better atom economy.
– Various sources and studies on the production methods.

Sodium carbonate (Wikipedia)

Sodium carbonate (also known as washing soda, soda ash and soda crystals) is the inorganic compound with the formula Na2CO3 and its various hydrates. All forms are white, odourless, water-soluble salts that yield alkaline solutions in water. Historically, it was extracted from the ashes of plants grown in sodium-rich soils, and because the ashes of these sodium-rich plants were noticeably different from ashes of wood (once used to produce potash), sodium carbonate became known as "soda ash". It is produced in large quantities from sodium chloride and limestone by the Solvay process, as well as by carbonating sodium hydroxide which is made using the Chlor-alkali process.

Sodium carbonate
Skeletal formula of sodium carbonate
Sample of sodium carbonate
IUPAC name
Sodium carbonate
Other names
Soda ash, washing soda, soda crystals, sodium trioxocarbonate
3D model (JSmol)
ECHA InfoCard 100.007.127 Edit this at Wikidata
EC Number
  • 207-838-8
E number E500(i) (acidity regulators, ...)
RTECS number
  • VZ4050000
  • InChI=1S/CH2O3.2Na/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2 checkY
  • InChI=1/NaHCO3.2Na/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2
  • [Na+].[Na+].[O-]C([O-])=O
Molar mass 105.9888 g/mol (anhydrous)
286.1416 g/mol (decahydrate)
Appearance White solid, hygroscopic
Odor Odorless
  • 2.54 g/cm3 (25 °C, anhydrous)
  • 1.92 g/cm3 (856 °C)
  • 2.25 g/cm3 (monohydrate)
  • 1.51 g/cm3 (heptahydrate)
  • 1.46 g/cm3 (decahydrate)
Melting point 851 °C (1,564 °F; 1,124 K) (Anhydrous)
100 °C (212 °F; 373 K)
decomposes (monohydrate)
33.5 °C (92.3 °F; 306.6 K)
decomposes (heptahydrate)
34 °C (93 °F; 307 K)
Anhydrous, g/100 mL:
  • 7 (0 °C)
  • 16.4 (15 °C)
  • 34.07 (27.8 °C)
  • 48.69 (34.8 °C)
  • 48.1 (41.9 °C)
  • 45.62 (60 °C)
  • 43.6 (100 °C)
Solubility Soluble in aq. alkalis, glycerol
Slightly soluble in aq. alcohol
Insoluble in CS2, acetone, alkyl acetates, alcohol, benzonitrile, liquid ammonia
Solubility in glycerine 98.3 g/100 g (155 °C)
Solubility in ethanediol 3.46 g/100 g (20 °C)
Solubility in dimethylformamide 0.5 g/kg
Acidity (pKa) 10.33
−4.1·10−5 cm3/mol
1.485 (anhydrous)
1.420 (monohydrate)
1.405 (decahydrate)
Viscosity 3.4 cP (887 °C)
Monoclinic (γ-form, β-form, δ-form, anhydrous)
Orthorhombic (monohydrate, heptahydrate)
C2/m, No. 12 (γ-form, anhydrous, 170 K)
C2/m, No. 12 (β-form, anhydrous, 628 K)
P21/n, No. 14 (δ-form, anhydrous, 110 K)
Pca21, No. 29 (monohydrate)
Pbca, No. 61 (heptahydrate)
2/m (γ-form, β-form, δ-form, anhydrous)
mm2 (monohydrate)
2/m 2/m 2/m (heptahydrate)
a = 8.920(7) Å, b = 5.245(5) Å, c = 6.050(5) Å (γ-form, anhydrous, 295 K)
α = 90°, β = 101.35(8)°, γ = 90°
Octahedral (Na+, anhydrous)
112.3 J/mol·K
135 J/mol·K
−1130.7 kJ/mol
−1044.4 kJ/mol
Occupational safety and health (OHS/OSH):
Main hazards
GHS labelling:
GHS07: Exclamation mark
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
Lethal dose or concentration (LD, LC):
4090 mg/kg (rat, oral)
Safety data sheet (SDS) MSDS
Related compounds
Other anions
Sodium bicarbonate
Other cations
Lithium carbonate
Potassium carbonate
Rubidium carbonate
Cesium carbonate
Related compounds
Sodium sesquicarbonate
Sodium percarbonate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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