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Proton ionization constant

Peroxophosphoric Acids and Their Salts. In its usual impure form (H PO is the main contaminant), peroxomonophosphoric acid [13598-52-2] (5), is a viscous, coloress Hquid. The three ionization constants for peroxomonophosphoric acid are pifj = 1.1, P-A2 = 5.5, and pK (peroxide proton) = 12.8 (44). Oxidations comparable to those of peroxomonosulfuric acid, H2SO, occur in acid solutions of ca pH 2, but at higher pH values, H PO becomes less reactive as an oxidant and more unstable with respect to decomposition (44). The stmcture of H PO is probably similar to that of... [Pg.93]

The ionization constant of a typical heterocyclic compound (e.g., quinoline) designates the equilibrium involving a proton, a neutral molecule and its cation. With quinazoline, however, two distinct species (hydrated and anhydrous) are involved each of which is in equilibrium with its cation, and can be represented as in the reaction scheme, (7), (8), (3), and (4). [Pg.259]

Protonation of pyrazine A-oxides takes place at the unsubstituted ring nitrogen as revealed by examination of their UV spectra and ionization constants in water. The same holds for unsubstituted quinoxaline A-oxide and the 3-amino derivative. Pyrazine and quinoxaline di-A-oxides are protonated at one A-oxide oxygen atom (74KGS1554). [Pg.295]

One of the most important types of aqueous equilibrium involves proton transfer from an acid to a base. In aqueous soiutions, water can act as an acid or a base. In the presence of an acid, symbolized HA, water acts as a base by accepting a proton. The equilibrium constant for transfer of a proton from an acid to a water molecule is caiied the acid ionization constant (Zg) ... [Pg.1185]

In the presence of a base B, water acts as an acid by donating a proton, and the equiiibrium constant for the transfer of a proton from water to a base is caiied the base ionization constant (Zjj) ... [Pg.1185]

The ability of an acid to lose a proton (acid strength) is experimentally measured by its acid ionization constant the higher the value of this constant the higher is the concentration of H30+ ions, and the stronger the acid. [Pg.591]

Woolley, E. M. Hepler, L. G., Apparent ionization constants of water in aqueous organic mixtures and acid dissociation constants of protonated co-solvents in aqueous solution, Anal. Chem. 44, 1520-1523 (1972). [Pg.261]

Identify each of the following terms (a) hydronium ion, (h) Bronsted theory, (c) proton (Bronsted sense), (d) acid (Bronsted sense), (e) base (Bronstcd sense), (/) conjugate, (g) strong, (h) acid dissociation constant, (/) ionization constant, (/) base dissociation constant, (k) autoionization, (/) pH, and f/w) K .. [Pg.314]

Dissociation constant of silicic acid calculated according to the a + = [(Kacx Kw)/c]1/2fbrmula for dissociation of salts formed from weak acid and strong base a+ is the activity of protons (from pH), K w is the ionization constant of water, and c is the concentration of silicate solution. [Pg.38]

Most acid dissociation constants pKa exceed environmental pH values, the exceptions being the highly chlorinated phenols. As a result, these substances tend to have higher apparent solubilities in water because of dissociation. The structure-property relationships apply to the un-ionized or protonated species thus, experimental data should preferably be corrected to eliminate the effect of ionization, thus eliminating pH effects. [Pg.36]

The ionization and protonation equilibria for the doubly charged dimer have been determined in 3.0 M NaC104 medium but the values for these equilibrium constants can be expected to be affected by the great changes in ionic medium required (71)... [Pg.146]

The values for the ionization and protonation constants (0.21 and 0.24 respectively) indicate that [Mo205(OH2)6]2+ is the major dimeric species in 1.0 M acid with about equal concentrations of the other two dimers. The dimeric cationic species show a characteristic absorption band in the UV at —245 nm. [Pg.146]

The ionization constant. Kg, of the protonated betaine, Ci2H25N (CH3)(CH2C6H5)CH2C00H(BH+), was obtained by adding ml of... [Pg.62]

Catalysis by proton transfer is significant in the snbsnrface and associated environment and is common in homogeneous reactions. The strength of the acid or base is determined by the ionization constant, while its efficiency as a catalyst is controlled by the reaction rate. This relation, known as the Bronsted catalysis law, is expressed as... [Pg.296]

More important and more widely applicable criteria of protonation sites are available in the effects of more distant substituents, in particular meta and para in benzene derivatives, which are as a rule purely electronic in origin. Exceptionally, they may be complicated by steric effects (e.g., in polysubstituted derivatives). The most widely useful approach is that of Hammett (1940), who suggested that the effects of substituents on the ionization constants of benzoic acid may be taken as a measure of their effectiveness in other systems involving other reaction centres and in reactions other than acid-base equilibria. He thus defined substituent constants, a, by the equation... [Pg.281]

The basic ionization constants of a large number of 2,4-diaminopyrimidines and condensed pyrimidine derivatives have recently been measured and earlier values verified (Roth and Strelitz, 1969). The first protonation occurs at the N-1 ring atom (pAT = 7 40) and the effect of 5-substituents is correlated quite well with -constants for the -t-M substituents (p = 4 85). The —M substituents (—NO2, —CN) show an enhanced base-weakening effect, which may be accounted for in terms of the direct conjugation shown in [65]. This provides additional evidence for protonation at N-1. [Pg.317]

A graphical depiction of log(kjp) plotted as a function of log( Xa/p), where is the rate constant for general acid catalysis, is the acid ionization constant, p is the number of equivalent protons on the acid, and q is the number of equivalent positions where a proton can be... [Pg.99]

Tetramethylammonium 1,1,2,3,3-pentacyanopropenide is useful for preparation of pentacyanopropenide salts of other metal and quaternary ammonium cations by metathesis.8 The free acid, which may be obtained by use of an ion-exchange resin,3 has an ionization constant comparable to that of a strong mineral acid (pK < —8.5 the anion is not detectably protonated in 12M sulfuric acid).4... [Pg.51]


See other pages where Proton ionization constant is mentioned: [Pg.176]    [Pg.59]    [Pg.66]    [Pg.863]    [Pg.100]    [Pg.288]    [Pg.95]    [Pg.325]    [Pg.234]    [Pg.955]    [Pg.9]    [Pg.65]    [Pg.425]    [Pg.32]    [Pg.362]    [Pg.111]    [Pg.282]    [Pg.297]    [Pg.318]    [Pg.332]    [Pg.68]    [Pg.108]    [Pg.238]    [Pg.172]    [Pg.449]    [Pg.649]    [Pg.184]    [Pg.185]    [Pg.82]    [Pg.245]    [Pg.36]   
See also in sourсe #XX -- [ Pg.164 ]




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Constants protons

Ionization constant

Ionization constant constants

Proton ionizable

Protonation constant

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