Borax

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(Redirected from Sodium borate)
Borax
Image:Borax ball.jpg
General
Systematic name Sodium tetraborate
decahydrate
Molecular formula Na2B4O7·10H2O
Molar mass 381.37 g/mol
Appearance white solid
CAS number [1303-96-4]
Properties
Density and phase 1.73 g/cm3, solid
Solubility in water 5.1 g/100 ml (20 °C)
Melting point 75 °C
Boiling point 320 °C
Basicity (pKb) see text
Structure
Coordination
geometry 		 ?
Crystal structure  ?
Thermodynamic data
Std enthalpy of
formation ΔfHo298 		−3276.75 kJ/mol
Standard molar
entropy So298 		189.53 J·K−1·mol−1
Hazards
MSDS External MSDS
EU classification  
R-phrases  
S-phrases  
Flash point non-flammable
Supplementary data page
Structure and
properties 		n, εr, etc.
Thermodynamic
data 		Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Sodium aluminate
Sodium gallate
Other cations Potassium tetraborate
Related compounds Boric acid
Sodium perborate
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.

Image:Reagan Boraxo.gif

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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