Acid-consuming reactions

It can be seen, therefore, that ferrous iron and chalcopyrite oxidation are acid-consuming reactions, while pyrite oxidation and iron hydrolysis are acid-producing reactions. Thus, whether the overall reaction in a dump is acid producing or acid-consuming depends on the relative proportions of chalcopyrite and pyrite and on the pH conditions. In practice, sulfuric acid additions to the leach solution applied to the dump are usually required to overcome the acid consuming reactions of the gangue minerals and to keep the pH in a suitable range, typically 2 to 2.4, to optimize bacterial activity and minimize iron hydrolysis. 

Many gangue mineral reactions ate acid consuming, resulting in a dynamic steady-state pH suitable to support bacteria and maintain open poiceity. Important acid consuming reactions are ... 

Table 8.3. Acid-consuming reactions in solution, at soil-water interface, and used by microorganisms carbonate buffering (Eqs. 7-9), ion exchange (Eq. 10), silicate weathering (Eqs. 11-12), gibbsite dissolution (Eq. 13), goethite dissolution (Eq. 14), denitrification (Eq. 15) and desulfurication (Eq. 16 Stumm and Morgan 1981, MattheB 1990)...

Alkali Meta.IPhospha.tes, A significant proportion of the phosphoric acid consumed in the manufacture of industrial, food, and pharmaceutical phosphates in the United States is used for the production of sodium salts. Alkali metal orthophosphates generally exhibit congment solubility and are therefore usually manufactured by either crystallisation from solution or drying of the entire reaction mass. Alkaline-earth and other phosphate salts of polyvalent cations typically exhibit incongment solubility and are prepared either by precipitation from solution having a metal oxide/P20 ratio considerably lower than that of the product, or by drying a solution or slurry with the proper metal oxide/P20 ratio. 

The manufacture of alkyd resins (qv), which are obtained by the reactions of polybasic acids or anhydrides, polyhydric alcohols, and fatty oils and acids, consumes about 17% of the phthahc anhydride demand. While materials such as maleic anhydride, isophthahc acid, and fumaric acid can also be used, phthahc anhydride is the most important. The resin provides a binder for coatings that are apphed for either protection or decoration. Ak quahty concerns have put alkyd resins under pressure from water-based coatings which do not emit organic vapors upon drying. 

However, as HOX is consumed, hydrolysis is retarded because of build-up of free amine. Consumption of hypohalous acid through reaction with HX can result in formation of elemental halogen HOX + + X X2 + H2 O (1—3). The tendency for halogen formation is much greater for HOBr and... 

Dichlorine monoxide can be quantitatively determined alone or in admixture with CI2, by iodometry the acid consumed is a direct measure of CI2O (65). The reactions involved are... 

Large-Scale Industrial Production. Large amounts of chlorine dioxide ate used in pulp bleaching and smaller quantities ate used for the manufacture of sodium chlorite. In these appHcations, sodium chlorate is the only commercially available taw material. Chlorine dioxide production from sodium chlorate is achieved by the reduction of the chlorate ion in the presence of strong acid. The reaction consumes acid, so that acid and reducing agents must be constantly added to maintain the reaction. 

Diaziridines are also very strong oxidizing agents, even liberating chlorine from hydrochloric acid. The reaction with iodide in acidic solution proceeds almost quantitatively in most cases. The two equivalents of iodine obtained from a diaziridine (151) are of analytical value together with the number of acid equivalents consumed (B-67MI50800). 

In the direct method, a solution of the ammonium salt is treated with a solution of a strong base (e.g. sodium hydroxide) and the mixture distilled. Ammonia is quantitatively expelled, and is absorbed in an excess of standard acid. The excess of acid is back-titrated in the presence of methyl red (or methyl orange, methyl orange-indigo carmine, bromophenol blue, or bromocresol green). Each millilitre of 1M monoprotic acid consumed in the reaction is equivalent to 0.017032 g NH3 ... 

C06-0021. Determine the energy change per mole of NH3 consumed for the first step in nitric acid formation, reaction of ammonia with oxygen ... 

In addition to the sulfuric acid required for pH adjustment, some amount of acid is consumed by the reduction reaction (Equation 8.15). If sulfur dioxide is used as the reducing agent, it will provide all the acid consumed by this reaction, and additional acid will not be required. However, if sodium bisulfite or sodium metabisulfite is used, additional acid must be supplied to satisfy the acid demand. This acid requirement is stoichiometric and can be calculated from Equations 6.19 to 6.22. 

Malaprade explored the application of this reaction to compounds in which n was varied from zero to four. He carried out analyses for the periodic acid consumed and for the formaldehyde and formic acid formed. Using these methods, he worked out the details of the desired analysis for periodic acid and, as a corollary, an analysis for the polyhydric alcohols employed. 

The kinetics of the ionic hydrogenation of isobutyraldehyde were studied using [CpMo(CO)3H] as the hydride and CF3C02H as the acid [41]. The apparent rate decreases as the reaction proceeds, since the acid is consumed. However, when the acidity is held constant by a buffered solution in the presence of excess metal hydride, the reaction is first-order in acid. The reaction is also first-order in metal hydride concentration. A mechanism consistent with these kinetics results is shown in Scheme 7.8. Pre-equilibrium protonation of the aldehyde is followed by rate-determining hydride transfer. 

O-acylisourea generates peptide, the theoretical yield of peptide is one equivalent and one equivalent of A,/V -dialkylurea is liberated. However, a fourth and undesirable course of action is possible because of the nature the (9-acylisourea. The latter contains a basic nitrogen atom (C=NR3) in proximity to the activated carbonyl. This atom can act as a nucleophile, giving rise to a rearrangement (path J) that produces the. V-acylurea (see Section 1.12) that is a stable inert form of the acid. This reaction is irreversible and consumes starting acid without generating peptide. The exact fate of the O-acylisourea in any synthesis depends on a multitude of factors this is addressed in Section 2.3. 

The amount of ammonia volatilized was determined from the amount of standard sulfuric acid consumed in the traps. Ethylenediamine was determined by the salicylaldehyde method (14). The sample for cobalt(II) determination was made slightly acidic with hydrochloric acid immediately upon removal of the sample from the reaction flask, in order to prevent further oxidation of the cobalt (18). The carbon was removed by filtration, and the cobalt (II) concentration was determined spectrophotometrically as the cobalt-ammonium thiocyanate complex, (NH4)2Co(NCS)4 (28). 

Oxidation of Bis (1 -methyl-2-acetoxypropyl) selenide with Peracetic Acid. The reaction produced 0.75 mole of 3-acetoxy-l-butene per mole of peracetic acid consumed, and a new organoselenium compound was isolated from the reaction solution. NMR analysis of this compound led us to suggest that it was a substituted alkylselenenyl acetate of the following structure ... 

Oxidation of Bis (1-methyl-2-acetoxypropyl) selenide in the Presence of 2-Butene. The only product of the reaction was 3-acetoxy-l-butene. No epoxides and only traces of diols were detected in the reaction product. Approximately 0.85 mole of 3-acetoxy-l-butene was produced per mole of peracetic acid consumed, and approximately 90% of the original selenide was recovered unchanged. 

In highly polluted environment (several hundreds pptv of NO), 03 production is reduced because 03 is consumed by NO via reaction (8) which competes with reactions (4) and (5). Then NOz reacts with OH to form nitric acid (HN03). Reaction (8) is at the origin of low 03 mixing ratios under very high NOx conditions (Figure 1 adopted from [1]). 

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