Sodium carbonate

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 chloralkali process.

Sodium carbonate

Names
IUPAC name Sodium carbonate
Other names Soda ash, washing soda, soda crystals, sodium trioxocarbonate
Identifiers
CAS Number	497-19-8 (anhydrous) Y 5968-11-6 (monohydrate) Y 6132-02-1 (decahydrate) Y
3D model (JSmol)	Interactive image
ChEBI	CHEBI:29377 Y
ChEMBL	ChEMBL186314 Y
ChemSpider	9916 Y
ECHA InfoCard	100.007.127
EC Number	207-838-8
E number	E500(i) (acidity regulators, ...)
PubChem CID	10340
RTECS number	VZ4050000
UNII	45P3261C7T Y 2A1Q1Q3557 (monohydrate) Y LS505BG22I (decahydrate) Y
CompTox Dashboard (EPA)	DTXSID1029621
InChI InChI=1S/CH2O3.2Na/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2 Y Key: CDBYLPFSWZWCQE-UHFFFAOYSA-L Y InChI=1/NaHCO3.2Na/c2-1(3)4;;/h(H2,2,3,4);;/q;2*+1/p-2 Key: CDBYLPFSWZWCQE-NUQVWONBAP
SMILES [Na+].[Na+].[O-]C([O-])=O
Properties
Chemical formula	Na2CO3
Molar mass	105.9888 g/mol (anhydrous) 286.1416 g/mol (decahydrate)
Appearance	White solid, hygroscopic
Odor	Odorless
Density	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) (decahydrate)
Solubility in water	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
Magnetic susceptibility (χ)	−4.1·10−5 cm3/mol
Refractive index (nD)	1.485 (anhydrous) 1.420 (monohydrate) 1.405 (decahydrate)
Viscosity	3.4 cP (887 °C)
Structure
Crystal structure	Monoclinic (γ-form, β-form, δ-form, anhydrous) Orthorhombic (monohydrate, heptahydrate)
Space group	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)
Point group	2/m (γ-form, β-form, δ-form, anhydrous) mm2 (monohydrate) 2/m 2/m 2/m (heptahydrate)
Lattice constant	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°
Coordination geometry	Octahedral (Na+, anhydrous)
Thermochemistry
Heat capacity (C)	112.3 J/mol·K
Std molar entropy (S⦵298)	135 J/mol·K
Std enthalpy of formation (ΔfH⦵298)	−1130.7 kJ/mol
Gibbs free energy (ΔfG⦵)	−1044.4 kJ/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Irritant
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H313+H333, H319
Precautionary statements	P305+P351+P338
NFPA 704 (fire diamond)	2 0 0
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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). N verify (what is YN ?) Infobox references