Barium Chloride

Barium chloride has the formula, BaCl2 & is an ionic chemical compound. It is one of the most important water-soluble salts of barium-containing compounds. Like other barium salts, it is toxic & imparts a yellow-green coloration to a flame. It is also hygroscopic. Barium chloride was the by-product of the discovery of radium by Madame Curie (1898). When refining radium, the final separation resulted in barium chloride và radium chloride.

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BaCl2 crystalslovenija-expo2000.coms in both the cubic “fluorite” & “lead chloride” crystal structures, both of which accommodate the preference of the large Ba2+ ion for coordination numbers greater than six. There are four structure types known (Fig. 2.21).

FIGURE 2.21.

Cell Parameters

Fe2P type: a = 4.059 Å, b = c = 7.083 Å, α = 120°, β = γ = 90°, cell volume = 176.31 Å, cell occupancy is shown in Table 2.68.

TABLE 2.68. Cell occupany is:

NoSite notationAtomMultiplicityWyckoffSite symmetryxyzOccupancy
1Cl1Cl3gm2m0.256831/21.0
2Cl2Cl3fm2m0.594611.0
3Ba1Ba2d−6..1/32/31/21.0
4Ba2Ba1a−62m1.0

PbCl2 type, SG = mP24: a = 4.604 Å, b = 8.613 Å, c = 11.901 Å, α = 92.6°, β = γ = 90°, cell volume = 471.48 Å3, cell occupancy is shown in Table 2.69.

TABLE 2.69.

NoSite notationAtomMultiplicityWyckoffSite symmetryxyzOccupancy
1Cl2Cl4e10.070.2270.0721.0
2Ba1Ba4e10.120.270.3341.0
3Cl4Cl4e10.1650.7270.241.0
4Ba2Ba4e10.380.2730.131.0
5Cl1Cl4e10.4550.2730.3551.0
6Cl3Cl4e10.710.2270.031.0

PbCl2 type, SG = 0P12: a = 4.732 Å, b = 7.872 Å, c = 9.425 Å, α = β = γ = 90°, cell volume = 651.08 Å3, cell occupancy is shown in Table 2.70.

TABLE 2.70.

NoSite notationAtomMultiplicityWyckoffSite symmetryxyzOccupancy
1Cl1Cl4c.m.0.02271/40.66211.0
2Cl2Cl4c.m.0.14251/40.07451.0
3Ba1Ba4c.m.0.23931/40.40451.0

In aqueous solution, BaCl2 behaves as a simple salt. In water, it is a 1:2 electrolyte and the solution exhibits a neutral pH. Electrolysis of molten barium chloride produces barium metal. This can be used for obtaining barium salts for commercial uses. Barium chloride reacts with sulfate ion to produce a thick white, insoluble precipitate of barium sulfate:

Ba2+(aq) + SO42−(aq) ⇒ BaSO4 (solid)

Oxalate effects a similar reaction:

BaCl2 (aq) + Na2C2O4 (aq) ⇒ BaC2O4 (solid) + 2NaCl (aq)

Barium chloride can be prepared from barium hydroxide or barium carbonate, the latter being found naturally as the mineral “Witherite”. These basic salts react to give hydrated barium chloride. On an industrial scale, it is prepared via a two-step process from the mineral “Baryte”:

BaSO4 + 4C ⇒ BaS + 4CO (gas)

This first step requires high temperatures. The second step requires fusion of the reactants:


BaS + CaCl2 ⇒ BaCl2 + CaS

The BaCl2 is then be leached out from the mixture with water. From water solutions of barium chloride, the dihydrate can then be crystalslovenija-expo2000.comd as trắng crystals, BaCl2·2H2O, which are colorless, translucent rhomboidal tablets or lamellae. The dihydrate is stable in the air at room temperature, but loses one-half of its water above 55 °C (131 °F), và becomes anhydrous at 121 °C (250 F). As a cheap, soluble salt of barium, barium chloride finds wide application in the laboratory. It is commonly used as a test for sulfate ion. In industry, barium chloride is mainly used chiefly in the synthesis of pigments and in the manufacture of rodenticides & pharmaceuticals. It is also used:

In the purification of brine solution in caustic chlorine plants,

In the manufacture of heat treatment salts,

For case hardening of steel,

In the manufacture of pigments,

In the manufacture of other barium salts such as barium hydroxide,

In fireworks to give a bright green color. However, its toxicity limits its applicability,

As a flux in the manufacture of magnesium metal,

For making màu sắc kinescope glass ceramics,

In wastewater treatment,

For the production of PVC stabislovenija-expo2000.comrs, oil lubricants, barium chromate and barium fluoride,

For stimulating the heart và other muscles for medicinal purposes,

For softening water,

For manufacturing of other barium salts used as pesticides, pigments, boiler detergent,

As a mordant in dyeing và printing textiles,

In the manufacture of caustic soda, polymers, and stabislovenija-expo2000.comrs.

Its solubility in water in grams per 100 ml of water is shown in Table 2.71.

TABLE 2.71.

SubstanceFormula0 °C10 °C15 °C20 °C30 °C50 °C70 °C80 °C90 °C
Barium chlorideBaCl231.233.535.838.140.846.252.555.859.4

J.M. WagesJr, in Encyclopedia of Analytical Science (Second Edition), 2005

Alternative Precipitation

The direct amplification of silver can be carried out by precipitation with chromate. Ag2CrO4 is filtered & then treated with barium chloride for the precipitation of both BaCrO4 & AgCl. These precipitates are treated with Ag+ và thus 1 mol of Ag2CrO4 và 2 mol of AgCl are formed.

The process can be repeated, và on each treatment with BaCl2 an amount of silver chloride equivalent to lớn twice the original silver chromate is produced; after n cycles 2(n+1) moles AgCl can be found.

This procedure can also be applied for the indirect determination of CrO42−, by measuring the AgCl obtained.

One other indirect amplification, similar lớn those mentioned, is the amplification of phosphate by precipitation of silver phosphate và its conversion lớn silver chromate.


A particular case of the alternative precipitation method, which Weisz called cyclic amplification by fixation of both ions of an amplifiable compound, requires that the substance to lớn be amplified be subjected khổng lồ a series of stoichiometric reactions in order to lớn enhance its mass.

Scheme 5 for the amplification of hexacyanoferrate(II), via precipitation of the silver salt & formation of silver chloride & Prussian blue by reaction with iron chloride, shows that it is a particular case of the alternative precipitation method in which the amplification takes place by a cyclic procedure.

*

Its CAS number is 7787-39-5. It occurs as white, monoclinic crystals with a mật độ trùng lặp từ khóa of 4.44 g/cm3. Its solubility in water is low (0.001125 g/100 ml) và it is insoluble in ethanol. When heated, it decomposes at 480 °C khổng lồ the oxide & SO2 gas.

It has been used as a weighting material on oil-drilling rigs to prevent “blow out” during drilling operations. This salt is used for such purposes, presumably because of its ability lớn absorb SO2 and H2S gases trapped in the rocks as drilling proceeds. The demand for barium sulfite is low.

Very little scientific studies of barium sulfite have ensued in the literature. The physical properties of this salt remain unspecified. One paper presents the formation of spherulites of SrSO3 & BaSO3, synthesized in agar–agar gels (0–40 °C). The reactants were sodium sulfite and the chloride of the respective metals. Each spherulite consists of fibrous crystals which are arranged minutely in a radial manner from the center. A linear relation was recognized between (mean diameter)2 and reaction time in the same manner as the CaSO3 0.5H2O spherulite reported. The slopes of the lines, namely the growth rates of the spherulites, were greater in the order of calcium sulfite > strontium sulfite > barium sulfite. The ratio of (mean diameter)2/time was dependent upon the concentration of the agar–agar gel (0.5%–2.0%) & the reaction temperature (0–40 °C); the ratios decreased linearly with an increase of the gel concentration và increased with an increase of temperature.

Barium sulfite is available in limited quantities, commercially.

ValueUnitsOrgan/ TissuePrep. Và Route of Admin.Cell Line/ TypeEffectsExp. Over PointReferenceComments
Human
LD501gm for 70 kgp.o.(barium chloride)Machata (1988)
Rats
LD50630mg/kgp.o. (barium carbonate)Lewis & Sweet (1984)
LD50118mg/kgp.o. (barium chloride)Lewis và Sweet (1984)
LD50921mg/kgp.o. (barium acetate)Lewis and Sweet (1984)
Mice
LD508.12mg/kgi.v. (barium chloride)Syed và Hosain (1972)
LD508.49mg/kgi.v. (barium nitrate)Syed và Hosain (1972)
LD5011.32mg/kgi.v. (barium acetate)Syed and Hosain (1972)
Rabbit
LD5055mg/kgi.v. (barium chloride)(http://rais.ornl.gov/tox/profiles/barium_f_V1.shtml%23t21)
LD5096mg/kgi.v. (barium acetate)(http://rais.ornl.gov/tox/profiles/barium_f_V1.shtml%23t21)

Procedure.

Accurately weigh 1 g of the finely powdered rock material into a PTFE dish, moisten with water and showroom in succession, 15 ml of concentrated nitric acid, 2 ml of concentrated hydrochloric acid & 10 ml of concentrated hydrofluoric acid. Cover the dish and set aside overnight. Remove the cover & evaporate to lớn dryness on a steam bath. If the rock powder is completely decomposed, địa chỉ a few ml of water and 10 ml of concentrated nitric acid và again evaporate lớn dryness. Repeat this last operation once more. If the decomposition is not complete after the first evaporation, add 5 ml of concentrated perchloric acid (60% w/v) and, if organic matter is present, 100 mg of vanadium pentoxide. In addition if the material is low in calcium, add not less than 100 mg of calcium chloride. (There should be present at least two equivalents of calcium for each equivalent of sulphur). Evaporate to dryness, and, if any organic or black mineral particles remain, evaporate with further portions of perchloric acid until the decomposition is complete.

After the final evaporation, địa chỉ 3 ml of concentrated hydrochloric acid và about 50 ml of water. Digest on the steam bath for 15 minutes with occasional stirring, then cool. Collect the residue on a small close-textured filter paper và wash well with warm water. Discard the residue. Transfer the filtrate to lớn a 250-ml separating funnel. Dilute lớn a volume of about 100 ml, và extract iron and titanium with successive 50-ral portions of cupferron solution until the extract is no longer brown. Wash the solution twice with 50-ml portions of chloroform, và finally with 50 ml of light petroleum. Run off the aqueous layer into a 400-ml beaker và wash the light petroleum twice with 10-ml portions of water. Dilute the combined aqueous layer & washings lớn about 200 ml, và filter if necessary.

Heat the solution khổng lồ boiling and add a slight excess of a hot barium chloride solution. Allow the solution lớn stand for an hour on a steam bath and then mix the beaker aside overnight. Collect the precipitated barium sulphate on a small close-textured filter paper và wash with successive small quantities of cold water. Transfer the paper khổng lồ a weighed platinum crucible, dry, ignite over the full flame of a Bunsen burner và weigh as BaSO4.

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After ignition, the barium sulphate residue should be perfectly white. Blank values are usually insignificant.