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| Names | |
|---|---|
| IUPAC name Sodium metasilicate | |
| Identifiers | |
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3D model (JSmol) | |
| Abbreviations | E550 |
| ChEBI | |
| ChemSpider |
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| ECHA InfoCard | 100.027.193 |
| EC Number |
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| MeSH | Sodium+metasilicate |
| RTECS number |
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| UNII |
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| UN number | 1759 3253 |
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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 inalcohol |
Refractive index (nD) | 1.52 |
| Thermochemistry | |
| 111.8 J/(K·mol) | |
Std molar entropy(S⦵298) | 113.71 J/(K·mol) |
Std enthalpy of formation(ΔfH⦵298) | −1561.43 kJ/mol |
Gibbs free energy(ΔfG⦵) | −1427 kJ/mol |
| Hazards | |
| GHS labelling: | |
  | |
| 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 theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Sodium metasilicate is thechemical substance with formulaNa
2SiO
3, which is the main component of commercialsodium silicate solutions. It is anionic compound consisting ofsodiumcationsNa+
and thepolymericmetasilicateanions [–SiO2−
3–]n. It is a colorless crystallinehygroscopic anddeliquescent solid, soluble in water (giving an alkaline solution) but not in alcohols.[1]
Theanhydrous compound can be prepared by fusingsilicon dioxideSiO
2 (silica,quartz) withsodium oxideNa
2O in 1:1 molar ratio.[2]
The compound crystallizes from solution as varioushydrates, 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 (wheren = 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 and13517-24-3 respectively.
Sodium Metasilicate reacts with acids to producesilica gel.[6]
