Acid-base dependent

Mamantov G., Osteryoung R. A., Acid-Base Dependent Redox Chemistry in Molten Chloroaluminates in Characterization of Solutes in Nonaqueous Solvents, G. Mamantov, ed., Plenum Press, New York, 1978, p. 223. 

The yellow solution on the left, containing 004 (chromate ion), was made acidic producing the reddish brown solution on the right. The principal component in solution is now Cr207 . Addition of base to this solution removes H ions and regenerates the yellow Cr04 . This is an example of an acid-base dependent chemical equilibrium. 

The usefulness of Frost diagrams becomes more apparent as the complexity of the different oxidation numbers increases. Consider the Frost diagram for Mn shown in Figure 5.1 I. Manganese can take a wide variety of oxidation states and its derivatives also have an acid-base dependence. 

ACID-BASE)-DEPENDENT GLOBULAR STRUCTURES OF PARTIALLY N-ALKYLATED POLY(TERTIARY AMINES)... 

As the term propping implies, the agent functions to prop or hold the fracture open. The fluid must have the proper viscosity and low friction pressure when pumped, it must break down and clean up rapidly when treatment is over, and it must provide good fluid-loss control (not dissipate). The fluid chemistry may be water, oil, or acid based, depending on the properties of the formation. Water-based fluids (slickwater) are the most widely used in shale formations because of their low cost, high performance, and ease of handling. 

If an acid is added to water, Eq. 5.5 describes the reaction, because the base in solution is water. Further, if a base is added to water, Eq. 5.6 describes the reaction, because now water is the acid. These acid-base reactions are critical to life itself, since nature s solvent is water. Having a good understanding of the thermodynamics of these reactions is not only important for understanding organic reactions in water, but is of the upper most importance in understanding biochemical reactions, almost all of which have acid-base dependencies. The factors that control the thermodynamics of acid-base reactions are the strengths of the acids or bases and the pH of the solution, so these measurements of acidity need to be examined in detail. 

Acids and bases can be classified as strong and/or weak acids/bases depending on their tendency to ionize. Strong acids completely ionize into H+, whereas weak acids only partially ionize or dissociate in water. 

Mills JD and Mitchell P (1982) Thiol modulation of CFo-CFi stimulates acid/base-dependent phosphorylation of ADP by broken pea chloroplasts, FEBS Lett. 144, 63-67. 

Jagendorf AT and Uribe E (1966) ATP formation caused by acid-base transition of spinach chloroplasts, Proc. Natl. Acad. Sci. JJSh 55, 170-177 Mills JD and Mitchell P (1982) Thiol modulation of CF -CF, stimulates acid-base dependent phosphorylation of ADP by broken a ailoroplasts, lEBS Lett. 144, 63-67... 

Mills JD and Mitchell P (1982) Thiol modulation of CF -CFj stimulates acid/ base-dependent phosphorylation by pea chloroplasts, FEBS Letters 144,63-67. Mills JD and Mitchell P (1983) Thiol modulation of the chloroplast ATPase and its effect on photophosphorylation, Biochim. Biophys. Acta, in press. Mitchell P (1981) Biochemical mechanism of protonmotivated phosphorylation in Fq-Fj ATPase molecules. In Lee CP et al, eds. Mitochondria and microsomes, pp 427-457. Boston,Mass Addison-Wesley. 

The chloroplasts H -ATP synthase, CFq-CF complex, has been isolated from spinach and reconstituted into liposomes. Such proteoliposomes were previously shown to catalyse ATP hydrolysis, Pi-ATP exchange, acid-base dependent ATP synthesis (Pick, Packer, 1979), light-dependent ATP synthesis (when reconstituted with bacteriorhodopsin (Dewey, Hammes, 1981) or with PSI (Hauska et al., 1980) and ATP-induced Ai formation (Shahak et al., 1982). 

These effects can be illustrated more quantitatively. The drop in the magnitude of the potential of mica with increasing salt is illustrated in Fig. V-7 here yp is reduced in the immobile layer by ion adsorption and specific ion effects are evident. In Fig. V-8, the pH is potential determining and alters the electrophoretic mobility. Carbon blacks are industrially important materials having various acid-base surface impurities depending on their source and heat treatment. 

Individual ammo acids differ m their acid-base properties This is important m peptides and proteins where the properties of the substance depend on its ammo acid constituents especially on the nature of the side chains It is also important m analyses m which a complex mixture of ammo acids is separated into its components by taking advantage of the differences m their proton donating and accepting power... 

The accuracy of a standardization depends on the quality of the reagents and glassware used to prepare standards. For example, in an acid-base titration, the amount of analyte is related to the absolute amount of titrant used in the analysis by the stoichiometry of the chemical reaction between the analyte and the titrant. The amount of titrant used is the product of the signal (which is the volume of titrant) and the titrant s concentration. Thus, the accuracy of a titrimetric analysis can be no better than the accuracy to which the titrant s concentration is known. 

A species that can serve as both a proton donor and a proton acceptor is called amphiprotic. Whether an amphiprotic species behaves as an acid or as a base depends on the equilibrium constants for the two competing reactions. For bicarbonate, the acid dissociation constant for reaction 6.8... 

Since the position of an acid-base equilibrium depends on the pH, the distribution ratio must also be pH-dependent. To derive an equation for D showing this dependency, we begin with the acid dissociation constant for HA. 

Two possible explanations for the effect of pH on the sensitivity of this analysis are the acid-base chemistry of NH4+, and, the acid-base chemistry of the enzyme. Given that the pfQ for NH4+ is 9.244, explain the source of this pH-dependent sensitivity. 

DNA polymerase enzymes all synthesize DNA by adding deoxynucleotides to the free 3 -OH group of an RNA or DNA primer sequence. The identity of the inserted nucleotide is deterrnined by its abiHty to base-pair with the template nucleic acid. The dependence of synthesis on a primer oligonucleotide means that synthesis of DNA proceeds only in a 5%o V direction if only one primer is available, all newly synthesized DNA sequences begin at the same point. 

Oxides and hydroxides react with HCl to form a salt and water as in a simple acid—base reaction. However, reactions with low solubiHty or insoluble oxides and hydroxides is complex and the rate is dependent on many factors similar to those for reactions with metals. Oxidizing agents such as H2O2, H2SeO, and V2O3 react with aqueous hydrochloric acid, forming water and chlorine. 

The susceptibihty of dialkyl peroxides to acids and bases depends on peroxide stmcture and the type and strength of the acid or base. In dilute aqueous sulfuric acid (<50%) di-Z fZ-butyl peroxide is resistant to reaction whereas in concentrated sulfuric acid this peroxide gradually forms polyisobutylene. In 50 wt % methanolic sulfuric acid, Z fZ-butyl methyl ether is produced in high yield (66). In acidic environments, unsymmetrical acychc alkyl aralkyl peroxides undergo carbon—oxygen fission, forming acychc alkyl hydroperoxides and aralkyl carbonium ions. The latter react with nucleophiles,... 

The relative contributions from these processes strongly depend on the reaction conditions, such as type of solvent, substrate and water concentration, and acidity of catalyst (78,79). It was also discovered that in acid—base inert solvents, such as methylene chloride, the basic assistance requited for the condensation process is provided by another silanol group. This phenomena, called intra—inter catalysis, controls the linear-to-cyclic products ratio, which is constant at a wide range of substrate concentrations. 

Prevention of Soil Crusting. Acid-based fertilizers such as Unocal s N/Furic (a mixture of urea with sulfuric acid), acidic polymers such as FMC s Spersal (a poly(maleic acid) derivative originally developed to treat boiler scale) (58), the anionic polyacrylamides described previously, as weU as lower molecular weight analogues such as Cytec s Aerotil L Soil Conditioner, have all been used successfully in at least some circumstances to prevent the formation of soil cmsts. It is difficult to prove benefits in the laboratory, and field tests may give variable results depending on local weather conditions. 

Fig. 9. Genesis of acid tain (13). From the oxidation of C, S, and N during the combustion of fossil fuels, there is a buildup in the atmosphere (gas phase, aerosol particles, raindrops, snowflakes, and fog) of CO2 and the oxides of S and N, which leads to acid—base interaction. The importance of absorption of gases into the various phases of gas, aerosol, and atmospheric water depends on a number of factors. The genesis of acid rain is shown on the upper right as an acid—base titration. The data given are representative of the environment in the vicinity of Zurich, Switzedand.

The thia2ides are actively secreted into the proximal tubules, where they exert their action on the luminal side of the tubules. The diuretic effect occurs within 1 h after oral adininistration, and the duration of action varies from 4 to 24 h depending on which thia2ide-type diuretic is used. The diuretic effects of the thia2ides are not influenced by acid—base conditions of the blood or urine. Probenecid, which also is secreted into the proximal tubules, may block the diuretic effects of the thia2ides. 

It turns out that in low-viscosity blending the acdual result does depend upon the measuring technique used to measure blend time. Two common techniques, wliich do not exhaust the possibilities in reported studies, are to use an acid-base indicator and inject an acid or base into the system that will result in a color change. One can also put a dye into the tank and measure the time for color to arrive at uniformity. Another system is to put in a conductivity probe and injecl a salt or other electrolyte into the system. With any given impeller type at constant power, the circulation time will increase with the D/T ratio of the impeller. Figure 18-18 shows that both circulation time and blend time decrease as D/T increases. The same is true for impeller speed. As impeller speed is increased with any impeller, blend time and circulation time are decreased (Fig. 18-19). 

A prototype of such phenomena can be seen in even the simplest carboxylic acid, acetic acid (CH3CHOOH). Acidity is determined by the energy or free energy difference between the dissociated and nondissociated forms, whose energetics usually depend significantly on their conformation, e.g., the syn/anti conformational change of the carboxyl-ate group in the compound substantially affects the acid-base equilibrium. The coupled conformation and solvent effects on acidity is treated in Ref. 20. 

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