Borax
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 |
? |
| 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 |
|
|
SI units were used where possible. Unless otherwise stated, standard conditions were used.
Disclaimer and references
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Borax, (
Na2B4O7·10
H2O,
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 a white chalky substance. Commercially sold borax is usually completely 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. 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.
