Sulfuric acid solution stoichiometry

Dibutyl phosphoric acid (HDBP) also dimerizes in nonpolar solvents and solutions of HDBP in kerosene contacting aqueous nitric acid equilibrate to produce (HDBP)2, HDBP-H2 0 and HDBP-HNOs in both phases. In addition, the organic phase contains (HDBP)2-H20 and the aqueous phase (Bu"0)2P02 (DBP ) in equilibrium with HOBR " Such equilibria complicate the stoichiometry of extraction from aqueous sulfuric acid solutions. Thus the extraction of... 

Attempts to measure the rates of S02 evolution from sulfuric acid solutions of hydrocarbons were without success due to the large solubility of the gas. The stoichiometry of these reactions, determined by freezing out the S02 from the solutions after the reactions were completed (Table VI), agreed closely with that predicted for alkenyl carbonium ion formation according to Eq. (12). 

If precursor complexes are formed in sulfuric acid solutions, they will almost certainly be mixed sulfate-carboxylate complexes, and the thermodynamic data will be of only peripheral use. In nitrate and especially perchlorate media, the thermodynamic data should be directly comparable as Ce(IV)-N03 complexes are weak and perchlorate complexes are unknown in aqueous solutions. It should be possible to compare the calculated constants with the kinetically derived data to gain further insight into the nature of the precursor complexes, and to assess the validity of authors claims with respect to complex stability and stoichiometry. 

It is apparent that Cr(C2C>4)3 3, m-Cr(OH2)2(0204)2 , and Cr(0H2)4C2044 react smoothly with cerium(IV) in acidic-sulfate media, 1 mole of oxalate being oxidized for each 2 moles of cerium(IV) consumed. The observations made are consistent with the view that the three reactions proceed, at least initially, according to the stoichiometries represented by the respective Reactions 3,1, and 2. The initial absorbances of reactant solutions (values obtained by extrapolation of measured absorbances to zero time) agree well with the values calculated, on the basis of Beer s law, from the absorptivity coefficients of the components. Further, as the reactions in 1.83Af sulfuric acid proceed, the absorbances of the solutions move toward the values expected for the assumed products at rates which demonstrate the reactions are first order in cerium(IV) and complex—see, for example, Figure 2. We thus find no indication that reaction intermediates contribute measurably to the absorbances of reactant solutions, or that reaction conditions cause the rapid equilibration of any of the oxalato complexes with other species... 

Oxidation of CS-> by H->Oo CS2 is fairly stable in acidic solutions but is quantitively oxidized to sulfuric acid by H202 in alkaline solutions (72,73). The overall stoichiometry for the reaction can be written as ... 

Oxidation of H>S by H>0-> H202 oxidizes H2S to sulfur in acidic and neutral conditions and to sulfate in alkaline conditions (83). The stoichiometry in acidic solution can be represented by ... 

The first evidence for the existence of a stable iodine cation was obtained by Masson (2) in 1938. He postulated the presence of Ig" and Ig in solutions of iodine and iodic acid in sulfuric acid in order to explain the stoichiometry of the reaction of such solutions with chlorobenzene to form both iodo and iodoso derivatives. Later, Symons and co-workers (6) gave conductometric evidence for I3 formed from iodic acid and iodine in 100% sulfuric acid and suggested that Ig" " may be formed on the basis of changes in the UV and visible spectra when iodine is added to la solutions. Gillespie and co-workers (7) on the basis of detailed conductometric and cryoscopic measurements confirmed that Ig is formed from HlOg and Ig in 100% sulfuric acid according to Eq. (1). The Ig cation may also be prepared in fluoro-... 

Determination of the total oxidizing power gives the amount of Xe(VIII) and may best be effected by dissolving the perxenate in a sodium iodide solution, acidifying with dilute perchloric or sulfuric acid, and titrating the liberated triiodide with thiosulfate. The reaction proceeds according to the overall stoichiometry ... 

When WTR are sufficiently acidified with sulfuric acid (H2SO4), insoluble aluminum hydroxide in the solution is converted to aluminum sulfate, which is soluble in the aqueous medium. The stoichiometry of this reaction can be written as follows ... 

The mechanism of U02 " extraction by monoalkyl phosphoric acid reagents appears to be a more complex process than for their dialkyl counterparts. This results from the polymerization of the monoalkyl phosphate in the organic phase and the hydration of the extracted uranyl species so that variable stoichiometries arise for the extractant/water/UO complex. The extraction of from sulfuric acid by mono-2,6,8-trimethylnonyl phosphoric acid (H2DDP) and mono-n-butyl phosphoric acid (H2MBP) as 0.05 M solutions in benzene was shown to follow equations (61) and (62) when an excess of extractant was present. When an excess of uranium was present, equations (63) and (64) applied where n, x, y and z were variable numbers which depended upon the extent of extractant polymerization and hydration of the extracted species. Synergistic effects may also be found with the monoalkyl phosphoric acid extractants and in one recent example the use of tri-n-octylphosphine ocxide (TOPO) as a synergist with H2MEHP allowed the extraction of U02 from phosphoric acid solutions. The uranium may be returned to the aqueous phase by contact with concentrated acid, which reverses the extraction process by protonation of the phosphate. 

Regeneration. The products formed by treating sulfur dioxide solutions with hydrogen sulfide depend in part on the pH. When hydrogen sulfide is added to a solution of sulfur dioxide in water, a complex mixture is formed that includes polythionic acids, thiosulfuric acid, and colloidal sulfur (in contrast to the crystalline sulfur obtained in the citrate process). This is known as Wackenroder s solution and has been extensively studied. The composition varies with the conditions used. With excess hydrogen sulfide the final product is ultimately approximately 100% sulfur (6). While the overall stoichiometry of the reaction is the same as the gas phase Claus reaction, the chemistry is more complex. 

The usefulness of the molarity concentration unit is readily apparent when dealing with reaction stoichiometry. For example, suppose that you want to know how many milliliters of 2.50 M sulfuric acid it t es to neutralize a solution containing 100.0 grams of sodium hydroxide. The first thing you must do is write the balanced chemical equation for the reaction ... 

At low chloride ion concentrations, the stoichiometry of the reaction corresponds to Eq. 69, but at high chloride ion concentrations, relatively more chlorine is formed (24, 99, 135, 193, 217, 226). Bray (24) observed that the ratio of chlorine to chlorine dioxide formed was 1.1 2 and that the ratio of chlorate ion that reacted to chloride ion that reacted was 1.12 1. He found that relatively more chlorine was formed at higher temperatures. Bray also reported that chloric acid reacted with concentrated hydrochloric acid at 60 C in the dark to produce essentially no chlorine dioxide. A solution that originally contained IN sulfuric acid, IM sodium chloride, and IM sodium chlorate yielded 1 part chlorine dioxide cUid 4000 parts chlorine as products. Hirschberg (94) found that the yield of chlorine dioxide could be increased markedly and the amount of chlorine produced correspondingly reduced by using small amounts of Ag" " and Mn catalysts. 

Another boron sulfide, of stoichiometry BS2, can be made by heating B2S3 and sulfur to 300°C under very carefully defined conditions. It is a colourless, moisture-sensitive material with a porphine-like molecular structure, BgSig, as shown in Fig. 6.29b. An alternative route to BgSie involves the reaction of dibromotrithiadiborolane with trithiocarbonic acid in an H2S generator in dilute CS2 solution ... 

Consistent with this, experiments using HS" labelled with radioactive (p. 661) show that acid hydrolysis of the 8203 produces elemental sulfur in which two-thirds of the activity is concentrated. Thiosulfates can also he made by boiling aqueous solutions of metal sulfites (or hydrogen sulfites) with elemental sulfur according to the stoichiometry... 

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