Borax, Sodium Borate


CAS Number: --

Molecular Weight: --

Chemical Formula:--

EINECS EC Number: --

FEMA: ----

Borax BP

Borax BP; Sodium Borate; Sodium Tetraborate
Na2B4O7,10H2O -- 381.4 -- 1303-96-4

Borax contains not less than 99.0 per cent and not more than the equivalent of 103.0  per cent of disodium tetraborate decahydrate.

A white, crystalline powder, colourless crystals or crystalline masses, efflorescent, soluble in water, very soluble in boiling water, freely soluble in glycerol.

A. To 1 ml of solution S (see Tests) add 0.1 ml of sulphuric acid and 5 ml of methanol \ and ignite. The flame has a green border.
B. To 5 ml of solution S add 0.1 ml of phph solution. The solution is red. On the addition of 5 ml of glycerol (85 per cent) the colour disappears.
C. Solution S gives the reactions of sodium.

Solution S
Dissolve 4.0 g in carbon dioxide-free water prepared from distilled water and  dilute to 100 ml with the same solvent.
Appearance of solution
Solution S is clear and colourless.
The pH of solution S is 9.0 to 9.6.
15 ml of solution S complies with the limit test for sulphates (50 ppm).
6 ml of solution S diluted to 14 ml with water complies with the limit test for  ammonium (10 ppm).
5 ml of solution S complies with limit test A for arsenic (5 ppm).
15 ml of solution S complies with the limit test for calcium (100 ppm).
Heavy metals
12 ml of solution S complies with limit test A for heavy metals (25 ppm).

Sodium Borate USP NF

Sodium Borate USP-NF; Borax USP NF
Na2B4O7-10H2O 381.37
Borax [1303-96-4]
Anhydrous 201.22 [1330-43-4]

Sodium Borate contains an amount of Na2B4O7 equivalent to not less than 99.0 percent and not more than 105.0 percent of Na2B4O7·10H2O.

Identification— A solution (1 in 20) responds to the tests for Sodium and for Borate.
Carbonate and bicarbonate— To 5 mL of a solution (1 in 20), contained in a test tube, add 1 mL of 3 N hydrochloric acid: no effervescence is observed.
Heavy metals— the limit is 0.002%.

Sodium Borate Decahydrate or Borax ACS Analytical Reagent

Sodium Tetraborate Decahydrate ACS
Na2B4O7 -10H2O
Formula Wt 381.37
CAS Number 1303-96-4

Assay: 99.5-105.0% Na2B4O7-10H2O
pH of a 0.01 M solution: 9.15-9.20 at 25C

Insoluble matter ........... 0.005%
Chloride (Cl) ............... 0.001%
Phosphate (PO4) ......... 0.001%
Sulfate (SO4) .............. 0.005%
Calcium (Ca) ............... 0.005%
Heavy metals (as Pb) ... 0.001%
Iron (Fe) ..................... 5 ppm