- Also called:
- sodium silicate or soluble glass
- Related Topics:
- chemical product
water glass
-
What is water glass in chemistry?
Water glass is a compound of sodium oxide ((Na_2O)) and silica (silicon dioxide, (SiO_2)), forming a glassy solid that dissolves in water. It is available as solid lumps, powders, or a clear, syrupy liquid.
Water glass is produced by roasting soda ash (sodium carbonate, (Na_2CO_3)) and silica sand ((SiO_2)) at high temperatures, yielding sodium silicate ((Na_2SiO_3)) and carbon dioxide ((CO_2)).
[Na_2CO_3 + SiO_2 \rightarrow Na_2O \cdot SiO_2 + CO_2]
It is used in laundry detergents, adhesives, water treatment, and concrete production. When dissolved, water glass is alkaline and helps remove fats, oils, and neutralize acids. It also helps filter water of undesirable suspended materials.
3 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What is water glass made of?
Water glass is a compound that contains sodium oxide ((Na_2O)) and silica (silicon dioxide, (SiO_2)), forming a glassy solid soluble in water. It is produced through roasting soda ash (sodium carbonate, (Na_2CO_3)) and silica sand at high temperatures, yielding sodium silicate ((Na_2SiO_3)) and carbon dioxide ((CO_2)). Alternatively, it can be made by dissolving silica sand in a heated aqueous solution of caustic soda (sodium hydroxide, (NaOH)). Water glass is available as solid lumps, powders, or a clear, syrupy liquid.
It is used in laundry detergents, as a binder and adhesive, and as a flocculant in water-treatment plants.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How is water glass created or produced?
Water glass, or sodium silicate, is a soluble compound of sodium oxide (Na₂O) and silica (silicon dioxide, SiO₂). It is produced by roasting soda ash (sodium carbonate, Na₂CO₃) and silica sand (SiO₂) in a furnace at 1,000 to 1,400 °C (1,800 to 2,500 °F). This process emits carbon dioxide (CO₂) and yields sodium silicate (Na₂SiO₃). The resulting fused glassy lumps, known as cullet, are cooled and sold as solids or powders. Alternatively, silica sand can be dissolved under pressure in a heated solution of caustic soda (sodium hydroxide, NaOH) to directly produce liquid sodium silicate.
Water glass is used in laundry detergents, adhesives, cements, and water treatment.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
What are common uses for water glass?
Water glass, a compound of sodium oxide ((Na_2O)) and silica ((SiO_2)), is a glassy solid soluble in water with many uses. It serves as a convenient source of sodium in industrial products, a builder in laundry detergents, and a binder and adhesive. Water glass also acts as a flocculant in water-treatment plants.
Liquid sodium silicate, formed by dissolving silica sand in a heated aqueous solution of sodium hydroxide (NaOH), reacts under acidic conditions to create a hard, glassy gel, useful as a bonding agent in concrete and abrasive wheels, and as an adhesive for glass or porcelain. It can also preserve eggs when they are stored in a cool environment while submerged in a viscous silicate solution.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
How does water glass react with other chemicals?
Water glass, a compound of sodium oxide ((Na_2O)) and silica ((SiO_2)), is soluble in water and reacts with other chemicals in various ways.
Under acidic conditions, liquid sodium silicate reacts to form a hard, glassy gel, making it useful as a bonding agent in cemented products like concrete and abrasive wheels, and as an adhesive for glass or porcelain.
When dissolved, water glass is moderately to highly alkaline. This helps remove fats and oils, neutralize acids, and break down starches and proteins. It can also adsorb metallic ions and help form flocs to filter water.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles. -
Why is water glass important in industry and science?
Water glass, a compound of sodium oxide ((Na_2O)) and silica ((SiO_2)), is a glassy solid soluble in water with many uses. It serves as a source of sodium in industrial products, a builder in detergents, an adhesive, and a flocculant in water treatment.
Since the 19th century, water glass has been made by roasting soda ash ((Na_2CO_3)) and silica sand ((SiO_2)) at high temperatures. The resulting cullet can be sold as lumps or powders, or dissolved in hot water to create a viscous liquid. Alternatively, dissolving silica sand in a heated solution of caustic soda (NaOH) can directly produce liquid sodium silicate.
In detergents, dissolved water glass helps remove fats and oils, neutralize acids, and break down starches and proteins. It also helps remove metallic ions and suspended materials in water treatment. Furthermore, it acts as a bonding agent in cemented products and an adhesive for glass or porcelain.
2 Britannica SourcesCreated from Britannica articles using AI. AI can make mistakes, so verify using Britannica articles.
water glass, a compound containing sodium oxide (Na2O) and silica (silicon dioxide, SiO2) that forms a glassy solid with the very useful property of being soluble in water. Water glass is sold as solid lumps or powders or as a clear, syrupy liquid. It is used as a convenient source of sodium for many industrial products, as a builder in laundry detergents, as a binder and adhesive, as a flocculant in water-treatment plants, and in many other applications.
Water glass has been manufactured since the 19th century, and the basic principles of making “silicate of soda” have not changed since that time. It is commonly produced by roasting various quantities of soda ash (sodium carbonate, Na2CO3) and silica sand (a ubiquitous source of SiO2) in a furnace at temperatures between about 1,000 and 1,400 °C (approximately 1,800 and 2,500 °F), a process that gives off carbon dioxide (CO2) and produces sodium silicate (Na2SiO3; usually represented by its two constituents, Na2O and SiO2): Na2CO3 + SiO2→ Na2O∙SiO2 + CO2
This roasting produces fused glassy lumps called cullet, which can be cooled and sold in that form or ground up and sold as powders. Lump or ground water glass in turn can be fed into pressurized reactors for dissolving in hot water. The solution is cooled to a viscous liquid and sold in containers ranging in size from small jars to large drums or tanks.
" height="20" alt="HEW Logo">
Sodium silicate liquid can also be prepared directly by dissolving silica sand under pressure in a heated aqueous solution of caustic soda (sodium hydroxide, NaOH): 2NaOH + SiO2 → Na2O∙SiO2 + H2O
In either production route, the higher the ratio of SiO2 to Na2O and the higher the concentration of both ingredients, the more viscous the solution. Viscosity is a product of the formation of silicate polymers, the silicon (Si) and oxygen (O) atoms being linked by covalent bonds into large negatively charged chain or ring structures that incorporate the positively charged sodium ions as well as water molecules. Highly viscous solutions can be spray-dried to form glasslike beads of hydrated sodium silicate. The beads can be packaged for sale to commercial users much like ground cullet, but they dissolve more readily than the anhydrous form of water glass.
These properties make hydrated sodium silicates ideal for use in one of their most common consumer products: powdered laundry and dishwasher detergents. Dissolved water glass is moderately to highly alkaline, and in detergents this property aids in the removal of fats and oils, the neutralization of acids, and the breakdown of starches and proteins. The same property makes the compound useful in the de-inking of wastepaper and in the bleaching of paper pulp.
Small quantities of dissolved water glass are used in the treatment of municipal water supplies as well as wastewater, where it adsorbs metallic ions and aids in the formation of loose agglomerations of particles called flocs, which filter the water of undesirable suspended materials.
The trusted destination for professionals, college students, and lifelong learners.
SUBSCRIBE
Liquid sodium silicate reacts under acidic conditions to form a hard glassy gel. This property makes it useful as a bonding agent in cemented products such as concrete and abrasive wheels. It is also an excellent adhesive for glass or porcelain.
A traditional use for dissolved water glass is as a preservative for eggs. Fresh eggs stored under cool conditions in a viscous silicate solution will keep for months.
There are many formulations of sodium silicate, depending on the amounts of Na2O and SiO2. Also, there are other silicate glasses in which the sodium is replaced by another alkali metal, such as potassium or lithium. Some glasses are better suited than others for particular applications, but they all share the same property of being a glassy solid that dissolves in water to form an alkaline solution.