sodium silicate, any one of several compounds containing sodium oxide, Na 2O, and silica , Si 2O, or a mixture of sodium silicates. Sodium ortho silicate is Na 4SiO 4 (or 2Na 2O·SiO 2); sodium meta silicate is Na 2SiO 3 (or Na 2O·SiO 2); sodium di silicate is Na 2Si 2O 5 (or Na 2O·2SiO 2); sodium tetra silicate is Na 2Si 4O 9 (or Na 2O·4SiO 2). All these compounds are transparent, glassy or crystalline solids that have high melting points (above 800°C) and are water soluble. They are produced chiefly by fusing sand and sodium carbonate in various proportions. The product is commonly known as water glass . The greatest single use of sodium silicates is as a raw material for making silica gel .
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