Chemical equations base dissociation constants

We recall that all sodium salts are soluble and that all soluble ionic salts are completely dissociated in H2O. We recognize that both NaCHsCOO and NaCN are salts of strong bases (which provide the cation) and weak acids (which provide the anion). The anions in such salts hydrolyze to give basic solutions. In the preceding text we determined that for CH3COO = 5.6 X 10" , and in Example 18-19 we determined that K, for CN" = 2.5 X 10 . As we have done before, we first write the appropriate chemical equation and equilibrium constant expression. Then we complete the reaction siunmary, substitute the algebraic representations of equilibriiun concentrations into the equilibrium constant expression, and solve for the desired concentration(s). 

First, the pyridine ring is protonated (Equation 1.25) the base dissociation constant of pyridine is K, = 1.49 x 10 . Next, the pyridinium ion undergoes a one-electron transfer to form the pyridinium radical (Equation 1.26). The reduction is coupled to a catalytic reaction of hydrogen generation (Equation 1.27). Hence, steps 2 and 3 constitute an EC sequence (where EC stands for an electrochemical step followed by a chemical step). A competing process, the inner-sphere interaction between the catalyst and the CO2 substrate, yields a radical pyridinium-C02 complex intermediate (Equation 1.28), which cleaves into a hydroxyformyl radical (Equation 1.29). When Pt and Pd electrodes are used, this anion radical can undergo a one-electron... 

At this point, we had to conclude that the wrong slope must have a mysterious reason outside our calculation methods, either in the experimental pKa scale or in the theoretical interpretation of pKa, although both alternatives seem equally strange and unlikely. Nevertheless, from a practical point of view, Eq. (10.3) is the most widely applicable and most accurate quantum chemically based pKa equation presently available, and it may be of great practical value in predicting the dissociation constants of... 

Whenever an organic acid contains two or more chemically identical (i.e., stereochemically equivalent) functional groups, statistical factors that originate in the entropy of formation of the acid and/or its conjugate base contribute to the variation of thermodynamic dissociation constants with the degree of dissociation of the acid. Such statistical effects are implicitly included in equations that are often used to describe acid-base equilibria in synthetic and natural polymers. Because those equations have frequently been applied to proton binding by humic substances, a brief discussion of statistical ef-... 

As mentioned in Section 3.7.1.2, there is a considerable scatter of solubility product values obtained in the molten KCl-NaCl eutectic using different methods of solubility determination. This disagreement in the solubility parameters may be explained by differences in the sizes of oxide particles whose solubility is to be determined. The difference in size causes the scatter of the solubility data according to the Ostwald-Freundlich equation and the employment of the isothermal saturation method, which implies the use of commercial powders (often pressed and sintered), leads to values which are considerably lower than those obtained by the potentiometric titration technique where the metal-oxides are formed in situ. Owing to this fact, the regularities connected with the effect of physico-chemical parameters of the oxides or the oxide cations should be derived only from solubility data obtained under the same or similar experimental conditions. However, this does not concern the dissociation constants of the oxides, since homogeneous acid-base equilibria are not sensitive to the properties of the solid phase of... 

The question about the relation between the reactivity of reactants and their structure is one of the fundamental problems of chemistry. This problem as one of the main directions of chemical kinetics was formulated in the general form about 100 years ago by N.A. Menshutkin in his works on hydrolysis of esters. One of the most important directions in this area is correlation equations relating the reaction rate constant to thermodynamic and structural parameters of reactants. The first correlation was proposed by Ch. Taylor (1914) who noticed a proportionality between the ionization rate constant of the catalyst and rate constant of the catalyzed reaction. The systematic work on correlations in chemical kinetics started from the works of J. BrSnsted and K. Pedersen who, using the results of their study of the reactions catalyzed by acids ( ha) and bases ( a), proposed the equations relating the rate constants of catalytic reactions to the dissociation constants of acids ituA (1924)... 

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