Boric Acid-Potassium Chloride

Boric Acid-Potassium Chloride, 0.2 M Dissolve 12.37 g of boric acid (H3BO3) and 14.91 g of potassium chloride (KC1) in sufficient water to make 1000.0 mL. 

Black Pepper Oil, 47, 572, (S 1)5 Black Peppier Oleoresin, 391, 392 Blank Tests, 4 Blank Titration, Residual, 4 Bleached Starch, 159 Bleidner Apparatus, (S3)17 Blue Litmus Paper, 861 Bois de Rose Oil, 47, 576 Boric Acid-Potassium Chloride, 0.2 M, 848... 

Boric acid-potassium chloride-sodium hydroxide... 

Alkaline Standard. Take 10 ml of the B.P. boric acid-potassium chloride-sodium hydroxide buffer solution at pH 8 7 and add 1 drop of 0 1 per cent solution of neutral red in 50 per cent ethanol and 3 drops of 01 per cent solution of phenolphthalein in 50 per cent ethanol. 

The presence of inorganic salts may enhance or depress the aqueous solubiUty of boric acid it is increased by potassium chloride as well as by potassium or sodium sulfate but decreased by lithium and sodium chlorides. Basic anions and other nucleophiles, notably borates and fluoride, greatly increase boric acid solubihty by forrning polyions (44). 

Recovery Process. Boron values are recovered from brine of Seades Lake by North American Chemicals Corp. In one process the brine is heated to remove some water and burkeite. The remaining brine is cooled to remove potassium chloride. This cooled brine is then transferred to another crystallizer where borax pentahydrate, Na2B40y 5H20, precipitates (18). In a separate process, boron is removed by Hquid—Hquid extraction followed by stripping with dilute sulfuric acid (19). Evaporator-crystallizers are used to recover boric acid [10043-35-3] H BO. In a third process, borax is recovered by refrigerating a carbonated brine. 

Four reagents are required for performance of this reaction. The first is a 0.1% ethanolic solution ofp-nitroso-A/iA -dimethylaniline. The second is pH 9.8 Clark and Lubs buffer, prepared by adding 40.8 mL of 0.2 M sodium hydroxide (carbon dioxide-free) to 50 mL of a 0.2M aqueous solution of both boric acid and potassium chloride. The third reagent is a 0.1% solution of phenol in ethanol, and the fourth reagent is a freshly prepared 1% aqueous solution of potassium ferricyanide. 

Uses Of the Stassfurt salts.—The magnesium compounds in the Stassfurt salts are used for the preparation of magnesium and of its salts. The potash salts are an essential constituent of many fertilizers used in agriculture, etc. 22 and potassium chloride is the starting-point for the manufacture of the many different kinds of potassium salts used in commerce—carbonate, hydroxide, nitrate, chlorate, chromate, alum, ferrocyanide, cyanide, iodide, bromide, etc. Chlorine and bromine are extracted by electrolysis and other processes from the mother liquids obtained in the purification of the potash salts. Boric acid and borax are prepared from boracite. Caesium and rubidium are recovered from the crude carnallite and sylvite. 

Substances that are ordinarily deliquescent are sulfuric add (concentrated), glycerol, calcium chloride crystals, sodium hydroxide (solid), and 100% ethyl alcohol. In an enclosed space, these substances deplete the water vapor present to a definite degree. Other substances are used to accomplish this end by chemical reaction, e.g.. phosphorus pentoxide (forming phosphoric acid), and boron trioxide (forming boric acid). Water is absorbed from nonmiscible liquids by addition of such substances as anhydrous sodium sulfate, potassium carbonate, anhydrous calcium chloride. and solid sodium hydroxide. The converse phenomenon is known as efflorescence. 

Fig. 4. Analysis of an anion standard solution by IC (a) and CE (b) [48]. IC conditions aVydac 302IC4.6 column, a flow-rate of 2.5 ml/min, an injection volume of 25 xl, an isophthalic acid mobile phase, UV detection at 280 nm. CE conditions an electrolyte of potassium dichromate, sodium tetraborate, boric acid and the DETA (diethylenetriamine) EOF modifier, pH 7.8 65 cmX75 xm I.D. capillary 20 kV indirect UV detection at 280 nm. Anions 1, chloride 2, nitrite 3, chlorate 4, nitrate 5, sulfate 6, thiocyanate 7, perchlorate 8, bromide.

The effect of neutral salts (e.g., NaCl) on the composition of borates precipitated from, or in equilibrium with, aqueous solutions doubtless arises from a reduction in water activity, metal borate complexation, and a shift in polyborate equilibria (Sections IV,A, B). The "indifferent or inert component method has frequently been used for the synthesis of borates. Potassium and sodium chlorides can be used to enhance the precipitation of specific nickel (48), aluminum (51), iron (49), and magnesium (151) borates. In the K20-B203-H20 system at 25°C (248), the presence of potassium chloride results in a reduced boric acid crystallization curve, lower borate solubilities, lower pH, and an extended B203 K20 range over which the pentaborate crystallizes. 

Boric acid is a relatively weak acid compared to other conunon acids, as illustrated by the acid equilibrium constants given in Table 4. Boric acid has a similar acid strength to sihcic acid. Calculated pH values based on the boric acid equihbrium constant are significantly higher than those observed experimentally. This anomaly has been attributed to secondary equilibria between B(OH)3, B(OH)4, and polyborate species. Interestingly, the aqueous solubihty of boric acid can be increased by the addition of salts such as potassium chloride and sodium sulfate, but decreased by the addition of others salts, such as the chlorides of lithium and sodium. Basic anions and other nucleophiles such as fluorides and borates significantly increase boric acid solubility. 

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