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| Names | |
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| IUPAC name
Sodium metasilicate | |
| Identifiers | |
 Y | |
3D model (JSmol) |
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| Abbreviations | E550 |
| ChEBI | |
| ChemSpider |
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| ECHA InfoCard | 100.027.193 
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| EC Number |
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| MeSH | Sodium+metasilicate |
PubChem CID |
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| RTECS number |
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| UNII |
Y |
| UN number | 1759 3253 |
CompTox Dashboard (EPA) |
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| Properties | |
| Na2SiO3 | |
| Molar mass | 122.062 g·mol−1 |
| Appearance | White crystals |
| Density | 2.61 g/cm3 |
| Melting point | 1,088 °C (1,990 °F; 1,361 K) |
| 22.2 g/100 ml (25 °C) 160.6 g/100 ml (80 °C) | |
| Solubility | insoluble in alcohol |
Refractive index (nD) |
1.52 |
| Thermochemistry | |
Heat capacity (C) |
111.8 J/(K·mol) |
Std molar |
113.71 J/(K·mol) |
Std enthalpy of |
−1561.43 kJ/mol |
Gibbs free energy (ΔfG⦵) |
−1427 kJ/mol |
| Hazards | |
| GHS labelling: | |
 
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| Danger | |
| H302, H314, H315, H319, H335 | |
| P260, P261, P264, P270, P271, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P330, P332+P313, P337+P313, P362, P363, P403+P233, P405, P501 | |
| NFPA 704 (fire diamond) | |
| Lethal dose or concentration (LD, LC): | |
LD50 (median dose) |
1153[clarification needed] (rat, oral) |
| Safety data sheet (SDS) | Avantor Performance Materials |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
Sodium metasilicate is the chemical substance with formula Na
2SiO
3, which is the main component of commercial sodium silicate solutions. It is an ionic compound consisting of sodium cations Na+
and the polymeric metasilicate anions [–SiO2−
3–]n. It is a colorless crystalline hygroscopic and deliquescent solid, soluble in water (giving an alkaline solution) but not in alcohols.[1]
The anhydrous compound can be prepared by fusing silicon dioxide SiO
2 (silica, quartz) with sodium oxide Na
2O in 1:1 molar ratio.[2]
The compound crystallizes from solution as various hydrates, such as
In the anhydrous solid, the metasilicate anion is actually polymeric, consisting of corner-shared {SiO4} tetrahedra, and not a discrete SiO32− ion.[4]
In addition to the anhydrous form, there are hydrates with the formula Na2SiO3·nH2O (where n = 5, 6, 8, 9), which contain the discrete, approximately tetrahedral anion SiO2(OH)22− with water of hydration. For example, the commercially available sodium silicate pentahydrate Na2SiO3·5H2O is formulated as Na2SiO2(OH)2·4H2O, and the nonahydrate Na2SiO3·9H2O is formulated as Na2SiO2(OH)2·8H2O.[5] The pentahydrate and nonahydrate forms have their own CAS Numbers, 10213-79-3 and 13517-24-3 respectively.
Sodium Metasilicate reacts with acids to produce silica gel.[6]
| Authority control databases: National |
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