Borax (Redirected from Sodium borate)
| Borax
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| General
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| Systematic name
| Sodium tetraborate
decahydrate
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| Molecular formula
| Na2B4O7·10H2O
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| Molar mass
| 381.37 g/mol
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| Appearance
| white solid
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| CAS number
| [1303-96-4]
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| Properties
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| Density and phase
| 1.73 g/cm3, solid
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| Solubility in water
| 5.1 g/100 ml (20 °C)
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| Melting point
| 75 °C
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| Boiling point
| 320 °C
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| Basicity (pKb)
| see text
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| Structure
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Coordination
geometry
| ?
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| Crystal structure
| ?
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| Thermodynamic data
|
Std enthalpy of
formation ΔfHo298
| −3276.75 kJ/mol
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Standard molar
entropy So298
| 189.53 J·K−1·mol−1
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| Hazards
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| MSDS
| External MSDS
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| EU classification
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| R-phrases
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| S-phrases
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| Flash point
| non-flammable
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| Supplementary data page
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Structure and
properties
| n, εr, etc.
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Thermodynamic
data
| Phase behaviour
Solid, liquid, gas
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| Spectral data
| UV, IR, NMR, MS
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| Related compounds
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| Other anions
| Sodium aluminate
Sodium gallate
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| Other cations
| Potassium tetraborate
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| Related compounds
| Boric acid
Sodium perborate
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Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references
|
Borax, also called 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 become the white chalky mineral tincalconite (Na2B4O7 · 5H2O). Commercially sold borax is usually partially dehydrated.
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.
Borax is widely used in detergents, water softeners, soaps, disinfectants, and pesticides. One of its most widely advertised uses was as a hand-cleaner for industrial workers. 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.
Large amounts of borax are used for manufacturing insulating fibreglass and in production of sodium perborate monohydrate for use in detergents.
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 jewelry metals such as gold or silver. It allows the molten solder to flow evenly over the joint in question.
When used in a mixture, borax can be used to kill carpenter ants, and fleas. Borax is also an ingredient in Slime.
The origin of the name is traceable to the Persian word bürah.
The word was also used disparagingly in the 1940s to refer to tawdrily designed modernistic furniture and other works of industrial design. Some say that the use came from advertisement displays for the household clearer, though the use may also derive from the Yiddish word "borachs," meaning rented furniture.
See also
External links
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