Borax
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| Properties | |
| General | |
|---|---|
| Name | Sodium tetraborate decahydrate |
| Chemical formula | Na2B4O7·10H2O |
| Appearance | White solid |
| Physical | |
| Formula weight | 381.4 amu |
| Melting point | Decomposes at 348 K (75 °C) |
| Density | 1.7 ×103 kg/m3 |
| Crystal structure | monoclinic (Spacegroup C2/c) for the decahydrate |
| Solubility | 55 g in 100g water |
| Thermochemistry | |
| ΔfH0solid | -6289kJ/mol |
| S0solid | 586 J/mol·K |
| Safety | |
| Ingestion | GI irritation, large doses may be fatal. |
| Inhalation | May cause irritation. |
| Skin | May cause irritation. |
| Eyes | May cause irritation. |
| More info | Hazardous Chemical Database (http://ull.chemistry.uakron.edu/erd/chemicals/9/8558.html) |
| SI units were used where possible. Unless otherwise stated, standard conditions were used. Disclaimer and references |
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Borax, (Na2B4O7·10H2O, sodium borate or sodium tetraborate) is an important boron compound. It is a soft white many-sided crystal that dissolves easily in water. If left exposed to dry air, it slowly loses its water of hydration and becomes the white chalky mineral tincalconite (Na2B4O7·5H2O). Commercially sold borax is usually partially dehydrated.
Borax_ball.jpg
Borax occurs naturally in evaporite deposits produced by the repeated evaporation of seasonal lakes (see playa). The most commercially important deposits are found near Boron, California and other locations in the American southwest, the Atacama desert in Chile, and in Tibet. Borax may also be produced synthetically from other boron compounds.
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Borax is widely used in detergents, water softeners, soaps, disinfectants, and pesticides. It is used in making enamel glazes, glass and strengthening pottery and ceramics. It is also easily converted to boric acid or borate, which have many applications.
A mixture of borax and ammonium chloride is used as a flux when welding iron and steel. It lowers the melting point of the unwanted iron oxide (scale), allowing it to run off.
Borax is also used mixed with water as a flux when soldering gold, silver etc. in jewelry. It allows the molten solder to flow evenly over the joint in question. Borax is an ingredient in Slime.
See also
es:Bórax fr:Borax it:Borace nl:Borax ja:ホウ砂 pl:Boraks pt:Bórax