Sodium metasilicate

Sodium metasilicate
Structural formula of polymeric sodium silicate
Ball and stick model of polymeric sodium silicate
Sample of sodium silicate in a vial
Names
IUPAC name
Sodium metasilicate
Identifiers
3D model (JSmol)
Abbreviations E550
ChEBI
ChemSpider
ECHA InfoCard 100.027.193
EC Number
  • 600-279-4229-912-9
MeSH Sodium+metasilicate
RTECS number
  • VV9275000
UNII
UN number 1759 3253
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
1.52
Thermochemistry
111.8 J/(K·mol)
113.71 J/(K·mol)
−1561.43 kJ/mol
−1427 kJ/mol
Hazards
Safety data sheet Avantor Performance Materials
GHS pictograms GHS05: CorrosiveGHS07: Harmful
GHS signal word Danger
H302, H314, H315, H318, H319, H335
P260, P261, P264, P270, P271, P280, P301+312, P301+330+331, P302+352, P303+361+353, P304+340, P305+351+338, P310, P312, P321, P330, P332+313, P337+313, P362, P363, P403+233, P405, P501
NFPA 704
Flammability code 0: Will not burn. E.g. waterHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
0
2
0
Lethal dose or concentration (LD, LC):
1153[clarification needed] (rat, oral)
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 metasilicate is the chemical substance with formula Na
2
SiO
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]

Preparation and properties

The anhydrous compound can be prepared by fusing silicon dioxide SiO
2
(silica, quartz) with sodium oxide Na
2
O
in 1:1 molar ratio.[2]

The compound crystallizes from solution as various hydrates, such as

  • pentahydrate Na
    2
    SiO
    3
    ·5H
    2
    O
    (CAS 10213-79-3, EC 229-912-9, PubChem, 57652358)
  • nonahydrate Na
    2
    SiO
    3
    ·9H
    2
    O
    (CAS 13517-24-3, EC 229-912-9, PubChem 57654617)[3]

Structure

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.

Uses

Sodium Metasilicate reacts with acids to produce silica gel.[6]

  • Cements and Binders - dehydrated sodium metasilicate forms cement or binding agent.
  • Pulp and Paper - sizing agent and buffer/stabilizing agent when mixed with hydrogen peroxide.
  • Soaps and Detergents - as an emulsifying and suspension agent.
  • Automotive applications - decommissioning of old engines (CARS program), cooling system sealant, exhaust repair.
  • Egg Preservative - seals eggs increasing shelf life.
  • Crafts - forms "stalagmites" by reacting with and precipitating metal ions.

See also

References

  1. ^ Chemical Book: "Sodium metasilicate". Accessed on 2018-05-13.
  2. ^ J. F. Schairer and N. L. Bowen (1956): "The system Na
    2
    O
    Al
    2
    O
    3
    SiO
    2
    ". American Journal of Science, volume 254, issue 3, pages 129-195 doi:10.2475/ajs.254.3.129
  3. ^ M. F. Bechtold (1955): "Polymerization and Properties of Dilute Aqueous Silicic Acid from Cation Exchange" Journal of Physical Chemistry, volume 59, issue 6, pages 532–541. doi:10.1021/j150528a013
  4. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
  5. ^ Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6
  6. ^ https://sciencing.com/uses-sodium-metasilicate-5447484.html