Barium evaporation

Hydrolysis of Potassium Ethyl Sulphate. Dissolve about i g. of the crystals in about 4 ml. of cold distilled water, and divide the solution into two portions, a) To one portion, add barium chloride solution. If pure potassium ethyl sulphate were used, no precipitate should now form, as barium ethyl sulphate is soluble in water. Actually however, almost all samples of potassium ethyl sulphate contain traces of potassium hydrogen sulphate formed by slight hydrolysis of the ethyl compound during the evaporation of its solution, and barium chloride almost invariably gives a faint precipitate of barium sulphate. b) To the second portion, add 2-3 drops of concentrated hydrochloric acid, and boil the mixture gently for about one minute. Cool, add distilled water if necessary until the solution has its former volume, and then add barium chloride as before. A markedly heavier precipitate of barium sulphate separates. The hydrolysis of the potassium ethyl sulphate is hastened considerably by the presence of the free acid Caustic alkalis have a similar, but not quite so rapid an effect. 

The precipitation of the barium sulphate must be performed with care, otherwise high results are obtained owing to occlusion of barium chloride in the barium sulphate. This is avoided by the following method, which has the further advantage that the tedious initial removal of the excess of nitric acid by evaporation is unnecessary. 

The palladium may be recovered by heating the spent catalyst to redness in order to remove organic impurities this treatment may reduce some of the barium sulphate to barium sulphide, which acts as a catalytic poison. The palladium is then dissolved out with aqua regia and the solution evaporated the residue is dissolved in hot water and hydrochloric acid to form palladium chloride. 

Thiosulfates are generally prepared by treating aqueous solutions of either calcium or barium thiosulfate with the corresponding carbonate or sulfate of the desired metal. The insoluble calcium or barium sulfates or carbonates are filtered and the thiosulfate recovered from the filtrate by vacuum evaporation. 

Barium nitrate is prepared by reaction of BaCO and nitric acid, filtration and evaporative crystallization, or by dissolving sodium nitrate in a saturated solution of barium chloride, with subsequent precipitation of barium nitrate. The precipitate is centrifuged, washed, and dried. Barium nitrate is used in pyrotechnic green flares, tracer buUets, primers, and in detonators. These make use of its property of easy decomposition as well as its characteristic green flame. A small amount is used as a source of barium oxide in enamels. 

Impurities in bromine may be deterrnined quantitatively (54). Weighing the residue after evaporation of a bromine sample yields the total nonvolatile matter. After removing the bromine, chloride ion may be deterrnined by titration with mercuric nitrate, and iodide ion by titration with thiosulfate water and organic compounds may be detected by infrared spectroscopy sulfur may be deterrnined turbidimetricaHy as barium sulfate and heavy metals may be deterrnined colorimetricaHy after conversion to sulfides. 

Barium bromide (2H2O) [7791-28-8] M 333.2, m at 75" loses first H2O and at 120" loses the second H2O. Crystd from water (ImL/g) by partial evaporation in a desiccator. 

The alcoholic filtrate is evaporated to 50 cc., and 50 g. of barium hydroxide and 150 cc. of distilled water are added (Note 4). The mixture is refluxed for two hours and the excess barium hydroxide is precipitated with carbon dioxide. The barium carbonate is removed by filtration and washed with hot distilled water. A slight excess of sulfuric acid is added to the filtrate to liberate the amino acid from its barium salt, and an excess of barium carbonate is added to remove sulfate ion. The mixture is digested on the steam bath until effervescence ceases, and it is then filtered and the precipitate is washed with hot distilled water. The filtrate and washings are concentrated on the steam bath to a volume of 100 cc., decolorized with i g. of active carbon, filtered, and concentrated to the point of crystallization (about 25 cc.). The amino acid is precipitated by the addition of 150 cc. of absolute alcohol and the product is collected and washed with absolute alcohol. 

Hydrogen peroxide was first made in 1818 by J. L. Thenard who acidified barium peroxide (p. 121) and then removed excess H2O by evaporation under reduced pressure. Later the compound was prepared by hydrolysis of peroxodisulfates obtained by electrolytic oxidation of acidified sulfate solutions at high current densities ... 

Crystalline barium bromite Ba(Br02)2-H20 was first isolated in 1959 it can be made by treating the hypobromite with Br2 at pH 11.2 and 0°C, followed by slow evaporation. Sr(Br02)2.2H20 was obtained similarly. 

In a 500-ml round-bottom flask fitted with a condenser, and a heating mantle is placed a mixture of 25 g of diethyl 5-(l -carboxy-2 -oxocyclohexyl)valerate, 70 g of barium hydroxide, and 200 ml of methanol, and the mixture is refluxed for 24 hours. After cooling, the mixture is acidified (pH 4) by cautious addition of cold 10% aqueous hydrochloric acid. The acidified solution is saturated with sodium chloride and then extracted three times with 100-ml portions of chloroform. The combined chloroform extracts are dried (anhydrous magnesium sulfate) and evaporated. On vacuum distillation, the residue affords the product (about 15 g), bp 176-17870.5 mm. 

Barium sulphate exhibits a marked tendency to carry down other salts (see co-precipitation, Section 11.5). Whether the results will be low or high will depend upon the nature of the co-precipitated salt. Thus barium chloride and barium nitrate are readily co-precipitated. These salts will be an addition to the true weight of the barium sulphate, hence the results will be high, since the chloride is unchanged upon ignition and the nitrate will yield barium oxide. The error due to the chloride will be considerably reduced by the very slow addition of hot dilute barium chloride solution to the hot sulphate solution, which is constantly stirred that due to the nitrate cannot be avoided, and hence nitrate ion must always be removed by evaporation with a large excess of hydrochloric acid before precipitation. Chlorate has a similar effect to nitrate, and is similarly removed. 

A solution of dibenzo[c,g][l,2]diazocine (206 mg, 1 mmol) and barium hydroxide octahydrate (0.5 g, 1.68 mmol) inluxing EtOH (50 mL) was treated with powdered zinc (0.5 g). Afterluxing for a few minutes, the solution became colorless and heating was discontinued. Dry ice (ca. 5 g) was added in small portions and the resulting suspension was filtered. The filtrate was evaporated to 20 mL and cooled to 0 C to afford colorless crystals yield 82 ing (40%) mp 168-169 C (dec.). 

Reduction of the chlorides by Ba, Na or Ca is a satisfactory method of preparing small amounts of pure Rb and Cs. Rubidium chloride is dissolved in barium azide aq sol and evaporated at 25°C to dryness. The intimate mixture is then heated under vacuum. The BafNjIj decomposes at ca. 100-200°C to Ba metal, which reduces RbCI to Rb this distills at temperatures low enough to prevent contamination by Ba vapor. The most widely employed method uses Ca as the reducing agent ... 

The material is impact-sensitive when dry and is supplied and stored damp with ethanol. It is used as a saturated solution and it is important to prevent total evaporation, or the slow growth of large crystals which may become dried and shock-sensitive. Lead drains must not be used, to avoid formation of the detonator, lead azide. Exposure to acid conditions may generate explosive hydrazoic acid [1], It has been stated that barium azide is relatively insensitive to impact but highly sensitive to friction [2], Strontium, and particularly calcium azides show much more marked explosive properties than barium azide. The explosive properties appear to be closely associated with the method of formation of the azide [3], Factors which affect the sensitivity of the azide include surface area, solvent used and ageing. Presence of barium metal, sodium or iron ions as impurities increases the sensitivity [4], Though not an endothermic compound (AH°f —22.17 kJ/mol, 0.1 kj/g), it may thermally decompose to barium nitride, rather than to the elements, when a considerable exotherm is produced (98.74 kJ/mol, 0.45 kJ/g of azide) [5]. 

MRH Barium chlorate 5.06/83, calcium chlorate 5.61/77, potassium chlorate 6.07/76, sodium bromate 4.98/80, sodium chlorate 7.32/75, zinc chlorate 6.11/76 Dry finely divided mixtures of red (or white) phosphorus with chlorates, bromates or iodates of barium, calcium, magnesium, potassium, sodium or zinc will readily explode on initiation by friction, impact or heat. Fires have been caused by accidental contact in the pocket between the red phosphorus in the friction strip on safety-match boxes and potassium chlorate tablets. Addition of a little water to a mixture of white or red phosphorus and potassium iodate causes a violent or explosive reaction. Addition of a little of a solution of phosphorus in carbon disulfide to potassium chlorate causes an explosion when the solvent evaporates. The extreme danger of mixtures of red phosphorus (or sulfur) with chlorates was recognised in the UK some 50 years ago when unlicenced preparation of such mixtures was prohibited by Orders in Council. 

Barium(II), concentration formation constant of chelates, 5 717t Barium 2-ethylhexanoate, 3 362 Barium acetate, 3 355 Barium acetate monohydrate, 3 355 Barium alloys, 3 344 Barium-aluminum evaporation getters, 3 349... 

Urine (2 1.) in a porcelain basin is evaporated to a syrup on the water bath. The flame is extinguished and the hot syrup is stirred with 500 c.c. of alcohol. After some time the clear extract is decanted and the residue is again warmed and once more digested in the same way with 500 c.c. of alcohol. If necessary, the combined extracts are filtered, most of the alcohol they contain is removed by distillation, and the aqueous-alcoholic residue, after transference to a small porcelain basin, is evaporated to dryness on the water bath. The dry residue is well cooled and is kept in an efficient freezing mixture while two volumes of colourless concentrated nitric acid are slowly added with thorough stirring. After the product has stood for twelve hours, the paste of urea nitrate is filtered dry at the pump, washed with a little ice-cold nitric acid (1 1), again filtered with suction till no more liquid drains off, and suspended in 100-150 c.c. of warm water. To this suspension barium carbonate is added... 

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