Acid and base strength

Control of the ionic properties of the polyelectrolyte, e.g. charge density and acid-base strength, is possible by simple proton adsorption because the charge carriers, commonly -NH3+X groups, are directly located along the polymer backbone. For numerous inorganic oxides, for example the silica or titania used, the adsorption of the PVAm can be carried out under condi-... 

The contents of this section should serve to show the versatility of the nitramide reaction for the study of catalysis by bases, and it will be quoted widely in the next chapter as a tool for investigating the relations between catalytic power and the structure and acid-base strength of catalysts. However, much of the work in non-aqueous media refers to solvents in which acid-base equilibria have not been adequately investigated, and it would certainly be of interest to extend kinetic measurements to solvents which have been the subject of modem equilibrium studies, for example the dipolar aprotic solvents mentioned in Chapter 4. 

In the overview to this chapter we noted that the experimentally determined end point should coincide with the titration s equivalence point. For an acid-base titration, the equivalence point is characterized by a pH level that is a function of the acid-base strengths and concentrations of the analyte and titrant. The pH at the end point, however, may or may not correspond to the pH at the equivalence point. To understand the relationship between end points and equivalence points we must know how the pH changes during a titration. In this section we will learn how to construct titration curves for several important types of acid-base titrations. Our... 

To use the above expression for measuring the strength of an acid, a standard acid-base pair, say A2-B2, must be chosen, and it is usually convenient to refer acid-base strength to the solvent. In water the acid-base pair H30 + -H20 is taken as the standard. The equilibrium defining acids is therefore ... 

For reviews of the relationship between hydrogen bond strength and acid-base properties, see Pogorelyi, V.K. Vishnyakova, T.B. Russ. Chem. Rev, 1984, 53, 1154 Epshtein, L.M. Russ. Chem. Rev, 1979, 48, 854. 

Flood, H., Forland, T. Roald, B. (1947). The acidic and basic properties of oxides. III. Relative acid-base strengths of some polyacids. Acta Chemica Scandinavica, 1, 790-8. 

Using the multisite complexation model (MUSIC), ° the surface of palladium oxide has been modeled providing useful data on the nature, number, and the acid-base strength of the hydroxyl groups present on the different faces (111) and (10 0) of... 

An inner-sphere complex is formed between Lewis acids and bases, while an outer-sphere complex involves a water molecule interposed between the acid and the base. A hard Lewis acid is a molecular unit of small size, high oxidation state, high electronegativity, and low polarizability whereas a soft Lewis acid is a molecular unit of relatively large size, characterized by low oxidation state, low electronegativity, and high polarizability. Based on this characterization, hard bases prefer to complex hard acids, and soft bases prefer to complex soft acids, under similar conditions of acid-base strength. 

In this chapter, a brief summary of studies that made use of calorimetry to characterize compounds comprising group IIIA elements (zeolites, nitrides, and oxides catalysts) was presented. It was demonstrated that adsorption microcalorimetry can be used as an efficient technique to characterize the acid-base strength of different types of materials and to provide information consistent with the catalytic data. 

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