Barium ions, reactions

During this reaction, some barium ions remain in the solution as chlorides and can be uti1i2ed for the preparation of other barium compounds. 

Barium metal and most barium compounds are highly poisonous. A notable exception is barium sulfate which is nontoxic because of its extreme iasolubihty ia water. Barium ion acts as a muscle stimulant and can cause death through ventricular fibrillation of the heart. Therefore, care must be taken to avoid contact with open areas of the skin. Workers must wear respirators (of type approved for toxic airborne particles), goggles, gloves, and protective clothing at all times. The toxic barium aluminate residue obtained from barium production is detoxified by reaction with a solution of ferrous sulfate and converted iato nontoxic barium sulfate. According to OSHA standards, the TWA value for Ba and Ba compounds ia air is 0.5 mg/m. ... 

Barium titanate is usually produced by the soHd-state reaction of barium carbonate and titanium dioxide. Dielectric and pie2oelectric properties of BaTiO can be affected by stoichiometry, micro stmcture, and additive ions that can enter into soHd solution. In the perovskite lattice, substitutions of Pb ", Sr ", Ca ", and Cd " can be made for part of the barium ions, maintaining the ferroelectric characteristics. Similarly, the TP" ion can partially be replaced with Sn +, Zr +, Ce +, and Th +. The possibihties for forming solution alloys in all these stmctures offer a range of compositions, which present a... 

Poloxamers are used primarily in aqueous solution and may be quantified in the aqueous phase by the use of compleximetric methods. However, a major limitation is that these techniques are essentially only capable of quantifying alkylene oxide groups and are by no means selective for poloxamers. The basis of these methods is the formation of a complex between a metal ion and the oxygen atoms that form the ether linkages. Reaction of this complex with an anion leads to the formation of a salt that, after precipitation or extraction, may be used for quantitation. A method reported to be rapid, simple, and consistently reproducible [18] involves a two-phase titration, which eliminates interferences from anionic surfactants. The poloxamer is complexed with potassium ions in an alkaline aqueous solution and extracted into dichloromethane as an ion pair with the titrant, tet-rakis (4-fluorophenyl) borate. The end point is defined by a color change resulting from the complexation of the indicator, Victoria Blue B, with excess titrant. The Wickbold [19] method, widely used to determine nonionic surfactants, has been applied to poloxamer type surfactants 120]. Essentially the method involves the formation in the presence of barium ions of a complex be-... 

Use Figures 10-5 and 10-6 or Table 10-1 to decide which of the following soluble substances would permit a separation of aqueous magnesium and barium ions. For those that are effective, write the equation for the reaction that occurs. 

The standard potential e of reaction (1) is 0.56 volt and of reaction (2) 0.60 volt. By suitably controlling the experimental conditions (e.g. by the addition of barium ions, which form the sparingly soluble barium manganate as a fine, granular precipitate), reaction (1) occurs almost exclusively. In moderately alkaline solutions permanganate is reduced quantitatively to manganese dioxide. The half-cell reaction is ... 

When a substance made up of ions is dissolved in water, the dissolved ions behave independently. That is, they undergo their own characteristic reactions regardless of what other ions may be present. For example, barium ions in solution, Ba2, always react with sulfate ions in solution, S04 , to form an insoluble ionic compound, BaS04(s), no matter what other ions are present in the barium solution. If a solution of barium chloride, BaCK, and a solution of sodium sulfate, Na S04, arc mixed, a white solid, barium sulfate, is produced. The solid can be separated from the solution by filtration, and the resulting solution contains sodium chloride, just as it would if solid NaCl were added to water. In other words, when the two solutions are mixed, the following reaction occurs ... 

This equation, therefore, represents the reaction between any aqueous solution containing barium ions and any aqueous solution containing sulphate ions. This ionic equation summarises the test for a sulphate ion in aqueous solution. 

Alkaline hydrolysis with barium, sodium, or lithium hydroxides (0.2-4 M) at 110°C for 18-70 h126-291 requires special reaction vessels and handling. Reaction mixtures are neutralized after hydrolysis and barium ions have to be removed by precipitation as their carbonate or sulfate salts prior to analysis which leads to loss of hydrolysate. Correspondingly, peptide contents are difficult to perform by this procedure. Preferred conditions for alkaline hydrolysis are 4M LiOH at 145 °C for 4-8 h where >95% of tryptophan is recovered 291 An additional inconvenience of the alkaline hydrolysis procedure is the dilution effect in the neutralization step and thus the difficult application to the analyzer if micro-scale analysis is to be performed. The main advantage is the good recovery of tryptophan and of acid-labile amino acid derivatives such as tyrosine-0-sulfate1261 (Section 6.6) as well as partial recovery of phosphoamino acids, particularly of threonine- and tyrosine-O-phosphate (Section 6.5). 

The chromate concentration was controlled through the solubility product of BaCr04 and the barium ion concentration. The equilibrium was followed by the reactions ... 

For each patient sample, 10 and 20 pi of leukocyte homogenate are transferred to individual wells on the microtiter plate. As two different incubation times are necessary, the same volumes of all samples are also pipetted into the lower part of the plate. Subsequently, 100 pi of substrate buffer is added to each well and the volume is adjusted to a total of 150 pi by adding sodium acetate buffer containing barium acetate. Arylsulfatase A will be inhibited in the presence of barium ions. The plate is briefly shaken, sealed with tape, and covered with aluminum wrapping. Incubation is carried out at 37°C for 30 min (upper half including the standard curve) and 90 min (lower half). The reaction is stopped with 200 pi stop solution and the absorbance is read at 490 nm. 

D In a double replacement reaction the positive and negative ions switch partners. Ammonium will bond with the nitrate ion and the barium ion will bond with phosphate. 

Reactions of barium ions Use a 025m solution of barium chloride BaCl2.2H20 or barium nitrate Ba(N03)2 for the study of these reactions. 

Write balanced equations to describe the oxidation of the following substances with strongly alkaline permanganate in the presence of barium ion (Stamm reaction) iodide, phosphite (HP03 ), hypophosphite (H2PO2 ), cyanide, thiocyanate, formate. 

The HCyDTA produced in turn reacts rapidly with lead ions, and there is no direct replacement of barium ions by lead ions. The rate of the reaction therefore can be adjusted by pH control. Some of the reactions are so fast that a pH as high as 8 is required for stopped-flow techniques to be applicable at the same time, this high pH makes copper and cobalt (instead of lead) unsuitable as scavenging metals. The sensitivity is such that as little as 10 M metal ion can be measured. It is important... 

B is correct. The precipitate would result when the sulfate ion from the reaction reacts with the barium ion to form barium sulfate. The bubbles would be created by the formation of nitrogen gas. 

The solubilin- of barium sulfate is also increased when acetate ions are added to an aqueous suspension of barium sulfate because acetate ions tend to form a soluble complex with barium ions, as shown by the reaction... 

When a substance made up of ions is dissolved in water, the dissolved ions undergo their own characteristic reactions regardless of what other ions may be present. For example, barium ions in solution always react with sulfate ions in solution to form an insoluble ionic compound. 

Analytical Group I-in metals interfere, and, in principle, they should be separated. Microgram amounts of some of them can be masked with EDTA [29]. Magnesium scarcely reacts with Chlorophosphonazo III in acidic media, so calcium can be determined in the presence of a 10-fold amount of magnesium [29]. At about pH 7, magnesium does react with Chlorophosphonazo III. Strontium and barium ions give colour reactions over a wide pH range. Preliminary separation of calcium from Mg, Sr and Ba is possible by extraction with Azo-azoxy BN. 

A similar analytical scheme for following the transformation of 3,4,6-tri-O-methyl-D-fructose gave somewhat better results. In these experiments, the disappearance of 3,4,6-tri-O-methyl-n-fructose was determined by measuring the formaldehyde released on periodate oxidation. The periodate consumption by these mixtures served as a check on the formation of products other than 3,4,6-tri-0-methyl-n-glucose and 3,4,6-tri-O-methyl-D-mannose, since each of the 3,4,6-tri-O-methylhexoses consumes 1 mole of periodate per mole. Actually, the periodate titers increased approximately 20% during the time-period that the apparent concentration of 3,4,6-tri-O-methyl-D-fructose diminished to about 60% of the initial concentration (when the reaction was carried out in sodium hydroxide solution). The change in periodate consumed was attributed to occurrence of demethylation. When the transformation was carried out in either calcium hydroxide or barium hydroxide solutions, the periodate consumption increased markedly. Hence, calcium and barium ions appear to catalyze this side reaction. ... 

Observe the reactions of the calcium, strontium, and barium ions with oxalate ions. 

A mixed convention will be employed in this chapter as an aid to indicate whether a given compound may be written in the ionized form. Thus, Ba (N03)2 should indicate to the student that barium nitrate has the overall composition of Ba(N03)2, that it is soluble and ionized, and that either the barium ion, Ba, or the nitrate ion, NO, may be written separately if desired. The absence of an ionic notation, as in AS2S5, means that only the neutral formula of the whole compound should be used. This mixed convention will not be uniformly used in subsequent chapters. Experienced chemists may write Ba(N03)2 in a reaction in aqueous solution, recognizing the ionic character of this salt even without an explicit ionic notation. 

All the elements in group IIA behave the same way, losing two electrons in chemical reactions to form ions with a 2+ charge. Each ion has two more protons in the nucleus than electrons outside the nucleus. The names of the ions are the names of the metal followed by ion as in barium ion, Ba2+. 

The hydrolytic ability of hydrochloric acid may be affected by salts present in the reaction mixture. The effect may be based on salting out of the hydrolysis products from the reaction mixture. For instance, magnesium and ammonium sulfates showed such an effect.117 Zinc and cadmium cations, as well as acetate and sulfate anions, decreased the hydrolysis rate with 0.1 M hydrochloric acid, whereas calcium, strontium, and barium ions exerted no effect.141 Neither copper metal, stainless steel, tin, nor sulfur dioxide impeded the hydrolysis with a solution of 0.03-0.05 M hydrochloric acid.142 There is a report143 that traces of metal salts affect the rate of hydrolysis but there are also contradicting findings144 145 that... 

The enthalpy of formation of barium ions is found to be -537.6 kJ/mol. We saw that these are to be formed from elements or hydrogen ions, and such a reaction is given by the complete equation ... 

A mixture of aqueous solutions of barium chloride and sodium sulfate contains the following ions Ba aq), Cl aq), Na aq), and S04 aq). According to solubility rules, most sulfate, sodium, and chloride salts are soluble. However, barium sulfate is insoluble. Since a barium ion and sulfate ion could combine to form insoluble barium sulfate, a reaction occurs. 

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