Keyestudio
Borax Sodium Tetraborate 10H2O 500gr
Borax Sodium Tetraborate 10H2O 500gr
Borax, also known as sodium borate, sodium tetraborate, or disodium tetraborate, is a compound with formula Na2H4B4O9•nH2O or, more precisely, [Na•(H2O)+m]2 [B4O5(OH)2−4].
The formula is often improperly written as Na2B4O7•(n+2)H2O, reflecting an older incorrect understanding of the anion‘s molecular structure. The name may refer to any of a number of closely related boron-containing mineral or chemical compounds that differ in their water of crystallization content. The most commonly encountered one is the octahydrate Na2H4B4O9•8H2O or [Na(H2O)+4]2 [B4O5(OH)2−4] (or Na2B4O7•10H2O, the “decahydrate”, in the older notation).[9] It is a colorless crystalline solid that dissolves in water.
Borax is a component of many detergents, cosmetics, and enamel glazes. It is used to make buffer solutions in biochemistry, as a fire retardant, as an anti-fungal compound, in the manufacture of fiberglass, as a flux in metallurgy, neutron-capture shields for radioactive sources, a texturing agent in cooking, as a cross-linking agent in slime, as an alkali in photographic developers, as a precursor for other boron compounds, and is useful as an insecticide (similarly to boric acid).
Chemical Properties
| Properties | |
|---|---|
| Na2B4O7·10H2O or Na2[B4O5(OH)4]·8H2O | |
| Molar mass | 201.22 (anhydrous) 381.38 (decahydrate) |
| Appearance | white solid |
| Density | 2.4 g/cm3 (anhydrous, solid)[1] 1.73 g/cm3 (decahydrate, solid)[1] |
| Melting point | 743 °C (1,369 °F; 1,016 K) (anhydrous)[1] 75 °C (decahydrate, decomposes)[1] |
| Boiling point | 1,575 °C (2,867 °F; 1,848 K) (anhydrous)[1] |
| 31.7 g/L (both)[1] | |
Chemical Structure Borax Sodium Tetraborate 10H2O 500gr
Safety
Borax, sodium tetraborate decahydrate, according to one study, is not acutely toxic. Its LD50 (median lethal dose) score is tested at 4.55-6.08 g/kg in rats as determined by US EPA (1969),[51] later in 1972 found to be 4.5 g/kg,[52] meaning that a significant dose of the chemical is needed to cause severe symptoms or death. The lethal dose is not necessarily the same for humans. On pesticide information websites it is listed as a non-lethal compound and of no hazardous concerns.
Borax has been in use as an insecticide in the United States with various restrictions since 1946. All restrictions were removed in February 1986 due to the low toxicity of borax, as reported in two EPA documents relating to boric acid and borax.[53][54]
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- EPA has determined that, because they are of low toxicity and occur naturally, boric acid and its sodium salts should be exempted from the requirement of a tolerance (maximum residue limit) for all raw agricultural commodities.[53]
Although it cited inconclusive data, a re-evaluation in 2006 by the EPA still found that “There were no signs of toxicity observed during the study and no evidence of cytotoxicity to the target organ.”
Description
Uses
Borax is used in various household laundry and cleaning products,[23] including the “20 Mule Team Borax” laundry booster, “Boraxo” powdered hand soap, and some tooth bleaching formulas.[24]
pH buffer
Borate ions (commonly supplied as boric acid) are used in biochemical and chemical laboratories to make buffers, e.g. for polyacrylamide gel electrophoresis of DNA and RNA, such as TBE buffer (borate buffered tris-hydroxymethylaminomethonium)[25][26] or the newer SB buffer or BBS buffer (borate buffered saline) in coating procedures. Borate buffers (usually at pH 8) are also used as preferential equilibration solution in dimethyl pimelimidate (DMP) based crosslinking reactions.
Co-complexing agent
Borax as a source of borate has been used to take advantage of the co-complexing ability of borate with other agents in water to form complex ions with various substances. Borate and a suitable polymer bed are used to chromatograph non-glycosylated hemoglobin differentially from glycosylated hemoglobin (chiefly HbA1c), which is an indicator of long-term hyperglycemia in diabetes mellitus.
Water-softening agent
Borax alone does not have a high affinity for the hardness cations, although it has been used for water-softening. Its chemical equation for water-softening is given below:
- Ca2+ (aq) + Na2B4O7 (aq) → Ca B4O7 (s)↓ + 2 Na+ (aq)
- Mg2+ (aq) + Na2B4O7 (aq) → Mg B4O7 (s)↓ + 2 Na+ (aq)
The sodium ions introduced do not make water ‘hard’. This method is suitable for removing both temporary and permanent types of hardness.
Food additive
Borax, given the E number E285, is used as a food additive, but is banned in some countries, including the United States, China,[31] and Thailand. As a consequence, certain foods, such as caviar, produced for sale in the United States contain higher levels of salt to assist preservation.[32] In addition to its use as a preservative, borax imparts a firm, rubbery texture to food.
