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Sodium metasilicate
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<h2 id="preparation-and-properties">Preparation and properties</h2> <p>The <a href="/facts/Anhydrous/A7B0fDLE">anhydrous</a> compound can be prepared by fusing <a href="/facts/Silicon_dioxide/A3WILp6J">silicon dioxide</a> SiO2 (silica, <a href="/facts/Quartz/4n86tE2G">quartz</a>) with <a href="/facts/Sodium_oxide/QbdIGb8u">sodium oxide</a> Na2O in 1:1 molar ratio.<a class="footnote-ref" id="fnref:2" href="#fn:2"><sup>2</sup></a> </p><p>The compound crystallizes from solution as various <a href="/facts/Hydrate/dev82l69">hydrates</a>, such as </p> <ul><li>pentahydrate Na2SiO3·5H2O (CAS 10213-79-3, EC 229-912-9, PubChem 57652358)</li> <li>nonahydrate Na2SiO3·9H2O (CAS 13517-24-3, EC 229-912-9, PubChem 57654617)<a class="footnote-ref" id="fnref:3" href="#fn:3"><sup>3</sup></a></li></ul> <h2 id="structure">Structure</h2> <p>In the anhydrous solid, the metasilicate anion is actually polymeric, consisting of corner-shared {SiO4} tetrahedra, and not a discrete SiO32− ion.<a class="footnote-ref" id="fnref:4" href="#fn:4"><sup>4</sup></a> </p><p>In addition to the anhydrous form, there are hydrates with the formula Na2SiO3·<i>n</i>H2O (where <i>n</i> = 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.<a class="footnote-ref" id="fnref:5" href="#fn:5"><sup>5</sup></a> The pentahydrate and nonahydrate forms have their own CAS Numbers, <a href="https://pubchem.ncbi.nlm.nih.gov/compound/Sodium_metasilicate_pentahydrate">10213-79-3</a> and <a href="https://pubchem.ncbi.nlm.nih.gov/compound/Sodium_metasilicate_nonahydrate">13517-24-3</a> respectively. </p> <h2 id="uses">Uses</h2> <p>Sodium Metasilicate reacts with acids to produce <a href="/facts/Silica_gel/qrNxnft5">silica gel</a>.<a class="footnote-ref" id="fnref:6" href="#fn:6"><sup>6</sup></a> </p> <ul><li>Cements and Binders - dehydrated sodium metasilicate forms cement or binding agent.</li> <li>Pulp and Par - sizing agent and buffer/stabilizing agent when mixed with hydrogen peroxide.</li> <li>Soaps and Detergents - as an emulsifying and suspension agent.</li> <li>Automotive applications - decommissioning of old engines (CARS program), cooling system sealant, exhaust repair.</li> <li>Egg Preservative - seals eggs increasing shelf life.</li> <li>Crafts - forms "stalagmites" by reacting with and precipitating metal ions. Also used as a glue called "<a href="/facts/Soluble_glass/055T0IYW">soluble glass</a>".</li> <li><a href="/facts/Hair_coloring/NyeYhUUF">Hair coloring</a> kits</li></ul> <h2 id="see-also">See also</h2> <ul><li><a href="/facts/Potassium_metasilicate/zfHUaIKK">Potassium metasilicate</a></li> <li><a href="/facts/Sodium_orthosilicate/6wVTqb1B">Sodium orthosilicate</a></li> <li><a href="/facts/Sodium_pyrosilicate/mX9D5jWr">Sodium pyrosilicate</a></li></ul> <h2 id="references">References</h2> <ol> <li id="fn:1"><p>Chemical Book: "Sodium metasilicate". Accessed on 2018-05-13. <a href="http://www.chemicalbook.com/ChemicalProductProperty_EN_CB2199386.htm" target="_blank">http://www.chemicalbook.com/ChemicalProductProperty_EN_CB2199386.htm</a> <a href="#fnref:1" class="footnote-back-ref">↩</a></p></li> <li id="fn:2"><p>J. F. Schairer and N. L. Bowen (1956): "The system Na2O—Al2O3—SiO2". American Journal of Science, volume 254, issue 3, pages 129-195 doi:10.2475/ajs.254.3.129 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:2" class="footnote-back-ref">↩</a></p></li> <li id="fn:3"><p>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 <a href="/wiki/Doi_(identifier)" target="_blank">/wiki/Doi_(identifier)</a> <a href="#fnref:3" class="footnote-back-ref">↩</a></p></li> <li id="fn:4"><p>Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8. <a href="978-0-08-037941-8" target="_blank">978-0-08-037941-8</a> <a href="#fnref:4" class="footnote-back-ref">↩</a></p></li> <li id="fn:5"><p>Wells A.F. (1984) Structural Inorganic Chemistry 5th edition Oxford Science Publications ISBN 0-19-855370-6 <a href="/wiki/ISBN_(identifier)" target="_blank">/wiki/ISBN_(identifier)</a> <a href="#fnref:5" class="footnote-back-ref">↩</a></p></li> <li id="fn:6"><p>"Uses of Sodium Metasilicate". 24 April 2017. <a href="https://sciencing.com/uses-sodium-metasilicate-5447484.html" target="_blank">https://sciencing.com/uses-sodium-metasilicate-5447484.html</a> <a href="#fnref:6" class="footnote-back-ref">↩</a></p></li> </ol>