Sodium carbonate
Skeletal formula of sodium carbonate
Space-filling model of sodium carbonate
Sample of sodium carbonate
Names
IUPAC name
Sodium carbonate
Other names
Soda ash, Washing soda, Soda crystals
Identifiers
CAS Number
497-19-8 (anhydrous)
5968-11-6 (monohydrate)
6132-02-1 (decahydrate)
3D model (JSmol)
Interactive image
ChEBI
CHEBI:29377
ChEMBL
ChEMBL186314
ChemSpider
9916
ECHA InfoCard 100.007.127
EC Number 207-838-8
E number E500 (acidity regulators, ...)
PubChem CID
10340
RTECS number VZ4050000
UNII
45P3261C7T
InChI[show]
SMILES[show]
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]
1.51 g/cm3 (heptahydrate)
1.46 g/cm3 (decahydrate)[2]
Melting point 851 C (1,564 F; 1,124 K)
decomposes (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)[2][6]
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)[3]
Solubility Soluble in aq. alkalis,[3] glycerol
Slightly soluble in aq. alcohol
Insoluble in CS2, acetone, alkyl acetates, alcohol, benzonitrile, liquid ammonia[4]
Solubility in glycerine 98.3 g/100 g (155 C)[4]
Solubility in ethanediol 3.46 g/100 g (20 C)[5]
Solubility in dimethylformamide 0.5 g/kg[5]
Basicity (pKb) 3.67
Magnetic susceptibility ()
4.1105 cm3/mol[2]
Refractive index (nD)
1.485 (anhydrous)
1.420 (monohydrate)[6]
1.405 (decahydrate)
Viscosity 3.4 cP (887 C)[5]
Structure
Crystal structure
Monoclinic (-form, -form, -form, anhydrous)[7]
Orthorhombic (monohydrate, heptahydrate)[1][8]
Space group
C2/m, No. 12 (-form, anhydrous, 170 K)
C2/m, No. 12 (-form, anhydrous, 628 K)
P21/n, No. 14 (-form, anhydrous, 110 K)[7]
Pca21, No. 29 (monohydrate)[1]
Pbca, No. 61 (heptahydrate)[8]
Point group
2/m (-form, -form, -form, anhydrous)[7]
mm2 (monohydrate)[1]
2/m 2/m 2/m (heptahydrate)[8]
Lattice constant
a = 8.920(7) , b = 5.245(5) , c = 6.050(5) (-form, anhydrous, 295 K)[7]
= 90, = 101.35(8), = 90
Coordination geometry
Octahedral (Na+, anhydrous)
Thermochemistry
Heat capacity (C)
112.3 J/molK[2]
Std molar
entropy (So298)
135 J/molK[2]
Std enthalpy of
formation (fHo298)
1130.7 kJ/mol[2][5]
Gibbs free energy (fG)
1044.4 kJ/mol[2]
Hazards
Main hazards Irritant
Safety data sheet MSDS
GHS pictograms The exclamation-mark pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)[9]
GHS signal word Warning
GHS hazard statements
H319[9]
GHS precautionary statements
P305+351+338[9]
NFPA 704
[11]
NFPA 704 four-colored diamond
010
Lethal dose or concentration (LD, LC):
LD50 (median dose)
4090 mg/kg (rat, oral) [10]
Related compounds
Other anions
Sodium bicarbonate
Other cations
Lithium carbonate
Potassium carbonate
Rubidium carbonate
Caesium 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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Infobox references
Sodium carbonate, Na2CO3, (also known as washing soda, soda ash and soda crystals, and in the monohydrate form as crystal carbonate) is the water-soluble sodium salt of carbonic acid.