Tetraborate, sodium

Sodium tetraborate Na2B407.10 H20 known as mineral tinkal (natural borax) is found on the shores of oertain lakes in Tibet and East Indies. These deposits were formerly exploited and the pure salt was obtained by crystallizing from the hot solution. 

Many methods are used to manufacture synthetic borax. First of all it is possible to manufacture borax if boric acid is gradually introduced into a solution of soda at 90 to 100 °C. After settling and separating insoluble substances by filtration, the solution is cooled in a crystallizer, in order to separate the crystals which are finally centrifuged. The mother liquor is used to dissolve new charges of soda ash. 

Borax can be prepared from mineral boronatrocalcite by the following method the finely ground mineral is decomposed in a boiling solution to which soda ash and the sodium hydrogen carborate are successively added in proportion so that the following reaction takes place  

The reaction proceeds in two stages. In the first stage the reaction components are heated by direct or indirect steam in wooden vats which are lined with lead and provided with stirrers. A small quantity of bleaching powder is added to oxidize and precipitate the iron. The insoluble residue separated by filtration of the solution is still containing a certain quantity of boric oxide it is, therefore, charged into an autoclave with a stirrer, where after the addition of a fresh 

The mineral rasorite (kernite), tetrahydrate of sodium tetraborate is a very suitable material for the production of borax. Its formula is Na3B407.  

Sodium tetraborate (SO-dee-um tet-ruh-BOR-ate) is a term used for either the anhydrous or hydrated form of the compound with the formula Na2B407. The decahydrate (Na2B407-ioH20) is also referred to as borax. Borax also occurs without water of hydration and in that form is known as anhydrous borax. 

Sodium tetraborate decahydrate. Red atoms are oxygen white atoms are hydrogen orange atoms are boron and turquoise atoms are sodium, publishers 

Sodium tetraborate is an odorless white crystalline solid or powder. The hydrated form loses its water of hydration when heated and then fuses (melts) to form a glass-like solid at higher temperatures. 

Sodium tetraborate occurs naturally as the minerals tincal (pronounced tinkle Na2B407 ioH30) and kernite 

Perhaps the best known commercial form of sodium tetraborate is called Twenty-Mule-Team Borax. The name comes from the fact that the first borax mines in California were located 165 miles from the nearest train station in Mojave, California. The mined borax was transported that distance in wagons pulled by 20 mules. Each wagon cost 900 to build, weighed 14,500 kilograms (32,000 pounds), and had wheels 2 

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Jeweler s borax, see Sodium tetraborate 10-water Jeweler s rouge, see Iron(III) oxide... 

Description of Method. The water-soluble vitamins Bi (thiamine hydrochloride), B2 (riboflavin), B3 (niacinamide), and Be (pyridoxine hydrochloride) may be determined by CZE using a pH 9 sodium tetraborate/sodlum dIhydrogen phosphate buffer or by MEKC using the same buffer with the addition of sodium dodecyl-sulfate. Detection Is by UV absorption at 200 nm. An Internal standard of o-ethoxybenzamide Is used to standardize the method. 

Procedure. A vitamin B complex tablet Is crushed and placed In a beaker with 20.00 mL of a 50% v/v methanol solution that Is 20 mM In sodium tetraborate and contains 100.0 ppm of o-ethoxybenzamIde. After mixing for 2 min to ensure that the B vitamins are dissolved, a 5.00-mL portion Is passed through a 0.45- xm filter to remove Insoluble binders. An approximately 4-nL sample Is loaded Into a 50- xm Internal diameter capillary column. For CZE the capillary column contains a 20 mM pH 9 sodium tetraborate/sodlum dIhydrogen phosphate buffer. For MEKC the buffer Is also 150 mM In sodium dodecylsulfate. A 40-kV/m electric field Is used to effect both the CZE and MEKC separations. 

In this experiment phosphate is determined by singlecolumn, or nonsuppressed, ion chromatography using an anionic column and a conductivity detector. The mobile phase is a mixture of n-butanol, acetonitrile, and water (containing sodium gluconate, boric acid, and sodium tetraborate). 

Boron. The principal materials used are borax [1303-96-4] sodium pentaborate, sodium tetraborate, partially dehydrated borates, boric acid [10043-35-3] and boron frits. Soil appHcation rates of boron for vegetable crops and alfalfa are usually in the range of 0.5—3 kg/hm. Lower rates are used for more sensitive crops. Both soil and foHar appHcation are practiced but soil appHcations remain effective longer. Boron toxicity is not often observed in field appHcations (see Boron compounds). 

Nondurable Finishes. Flame-retardant finishes that are not durable to launderiag and bleaching are, ia general, relatively iaexpensive and efficient (23). In some cases, a mixture of two or more salts is more effective than either of the components alone. For example, an add-on of 60% borax (sodium tetraborate) is required to prevent fabric from burning, and boric acid is iaeffective as a flame retardant even at levels equal to the weight of the fabric. However, a mixture of seven parts borax and three parts boric acid imparts flame resistance to a fabric with as Utde as 6.5% add-on. 

Wa.terBa.la.nce Chemicals. Water balance chemicals include muriatic acid, sodium bisulfate, and soda ash for pH control, sodium bicarbonate for alkalinity adjustment, and calcium chloride for hardness adjustment. A recent development is use of buffering agents for pH control. One of these products, sodium tetraborate, hydrolyzes to boric acid and a small amount of orthoborate (50) which provides significantly less buffering than carbonate and cyanurate alkalinity in the recommended pool pH range of 7.2—7.8 even at 100 ppm. 

Fig. 2. Electropherogram of real sample (homogenize of Drosophila flies heads). Electrolyte solution 7 mM sodium tetraborate, pH 8.14...

Chemical Designations - Synonyms Borax, anhydrous Sodium biborate Sodium pyroborate Sodium tetraborate,anhydrous Chemical Formula Na2B407. 

Dissolve 1.9 g di-sodium tetraborate decahydrate in 100 ml water and adjust the pH to 10.5 with caustic soda solution. 

Also sodium tetraborate (borax) and carborymethyl hydroxyethyl cellulose are used as retarding additives. 

Hydrated salts, as a rule, do not make good standards because of the difficulty of efficient drying. However, those salts which do not effloresce, such as sodium tetraborate Na2B407, 10H2O, and copper sulphate CuS04,5H20, are found by experiment to be satisfactory secondary standards.2... 

Boric acid behaves as a weak monoprotic acid with a dissociation constant of 6.4 x 10-10. The pH at the equivalence point in the titration of 0.2M sodium tetraborate with 0.2 M hydrochloric acid is that due to 0.1 M boric acid, i.e. 5.6. Further addition of hydrochloric acid will cause a sharp decrease of pH and any indicator covering the pH range 3.7-5.1 (and slightly beyond this) may be used suitable indicators are bromocresol green, methyl orange, bromophenol blue, and methyl red. 

In the second method a solution of the approximate strength required is prepared, and this is standardised against some standard alkaline substance, such as sodium tetraborate or anhydrous sodium carbonate standard potassium iodate or pure silver may also be used (see Section 10.84). If a solution of an exact strength is required, a solution of an approximate strength somewhat greater than that desired is first prepared this is suitably diluted with water after standardisation (for a typical calculation, see Appendix 17). 

B. Standardisation against sodium tetraborate. The advantages of sodium tetraborate decahydrate (borax) are (i) it has a large relative molecular mass, 381.44 (that of anhydrous sodium carbonate is 106.00) (ii) it is easily and economically purified by recrystallisation (iii) heating to constant weight is not required (iv) it is practically non-hygroscopic and (v) a sharp end point can be obtained with methyl red at room temperatures, since this indicator is not affected by the very weak boric acid. 

Procedure. Weigh out accurately from a weighing bottle 0.4-0.5g of pure sodium tetraborate into a 250 mL conical flask (Note 1), dissolve it in about 50 mL of water and add a few drops of methyl red. Titrate with the hydrochloric acid contained in a burette (for details, see under A) until the colour changes to pink (Note 2). Repeat the titration with two other portions. Calculate the... 

Calculation of the molarity. This is carried out as described in A. One mole of sodium tetraborate is 381.44 g. 

Procedure. Prepare an EGTA solution (0.05M) by dissolving 19.01 g in 100 mL sodium hydroxide solution (1M) and diluting to 1 L in a graduated flask with de-ionised water. Prepare the indicator by dissolving 0.065 g zincon in 2 mL sodium hydroxide solution (0.1M) and diluting to 100 mL with de-ionised water, and a buffer solution (pH 10) by dissolving 25 g sodium tetraborate, 3.5 g ammonium chloride, and 5.7 g sodium hydroxide in 1 L of de-ionised water. 

Either the Mohr titration or the adsorption indicator method may be used for the determination of chlorides in neutral solution by titration with standard 0.1M silver nitrate. If the solution is acid, neutralisation may be effected with chloride-free calcium carbonate, sodium tetraborate, or sodium hydrogencarbonate. Mineral acid may also be removed by neutralising most ofthe acid with ammonia solution and then adding an excess of ammonium acetate. Titration of the neutral solution, prepared with calcium carbonate, by the adsorption indicator method is rendered easier by the addition of 5 mL of 2 per cent dextrin solution this offsets the coagulating effect of the calcium ion. If the solution is basic, it may be neutralised with chloride-free nitric acid, using phenolphthalein as indicator. 

Bacterial activity is least when the pH lies between 9 and 10. The addition of a small amount, 0.1 g L 1, of sodium carbonate is advantageous to ensure the correct pH. In general, alkali hydroxides, sodium carbonate ( > 0.1 g L 1), and sodium tetraborate should not be added, since they tend to accelerate the decomposition ... 

Thermogravimetry is a valuable technique for the assessment of the purity of materials. Analytical reagents, especially those used in titrimetric analysis as primary standards, e.g. sodium carbonate, sodium tetraborate, and potassium hydrogenphthalate, have been examined. Many primary standards absorb appreciable amounts of water when exposed to moist atmospheres. TG data can show the extent of this absorption and hence the most suitable drying temperature for a given reagent may be determined. 

P3. 0.01 m Borax. Dissolve 3.81 g of sodium tetraborate Na2B4O7,10H2O in carbon dioxide-free water and dilute to 1 kg. The solution should be protected from exposure to atmospheric carbon dioxide, and replaced about a month after preparation. 

Prepare the buffer solutions for calibration of the pH meter if these are not already available the potassium hydrogenphthalate buffer (pH 4), and the sodium tetraborate buffer (pH 9.2) are the most commonly used for calibration purposes. 

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