Acid-base behavior

Acid-Base Behavior. The relative acidity-basicity of the filler, generally determined by measuring the pH value of a slurry of a specific mass of filler in 100 mL of deionized water, can influence the behavior of a filler in some systems. For example, the curing behavior of some elastomers is sensitive to the pH value of carbon black. 

A further important concept related to electronegativity and polarity is that of acidity and basicity. We ll see, in fact, that much of the chemistry of organic molecules can be explained by their acid-base behavior. You may recall from a course in general chemistry that there are two frequently used definitions of acidity the Brtfnsted-Lowry definition and the Lewis definition. We ll look at the... 

Walden, Paul, 360 Walden inversion. 359-360 Wang resin, solid-phase peptide synthesis and. 1037 Water, acid-base behavior of, 50 dipole moment of, 39 electrostatic potential map of. 53 nucleophilic addition reactions of, 705-706 pKaof, 51-52... 

This designation of the species H (aq) in terms of hydronium ion, H30+, is not necessitated by experimental evidence that proves the unique existence of this molecule, H30+, in dilute aqueous solutions (see Section 11-2.5). Nevertheless, the convenience of this assumption, as an aid in correlating acid-base behavior, amply justifies its use. 

Both our original prediction about the effect of ionization energy on acid-base behavior and the trend which we have observed in the first three elements lead us to expect that the hydroxide or oxide of silicon should not be basic, but perhaps should be weakly acidic. This is in fact observed. Silicon dioxide, Si02, can exist as a hydrated solid containing variable amounts of water,... 

The problem with the Arrhenius definitions is that they are specific to one particular solvent, water. When chemists studied nonaqueous solvents, such as liquid ammonia, they found that a number of substances showed the same pattern of acid-base behavior, but plainly the Arrhenius definitions could not be used. A major advance in our understanding of what it means to be an acid or a base came in 1923, when two chemists working independently, Thomas Lowry in England and Johannes Bronsted in Denmark, came up with the same idea. Their insight was to realize that the key process responsible for the properties of acids and bases was the transfer of a proton (a hydrogen ion) from one substance to another. The Bronsted-Lowry definition of acids and bases is as follows ... 

The pattern of oxidation states correlates with the pattern of acid-base behavior of d-metal oxides. Although most d-metal oxides are basic, the oxides of a given element show a shift toward acidic character with increasing oxidation number, just as the oxoacids do (recall Section 10.10). The family of chromium oxides is a good... 

Lewis Acid-Base Behavior in Aqueous Solution Some Implications for Metal Ions in Biology Robert D. Hancock and Arthur E. Martell... 

Hydronium cations, neutral water molecules, and hydroxide anions illustrate the effect of charge on acid-base behavior. 

LEWIS ACID-BASE BEHAVIOR IN AQUEOUS SOLUTION SOME IMPLICATIONS FOR METAL IONS... 

Thermodynamics of complex formation of silver with several ligands such amines,368 hindered pyridine bases,369 nitrogen donor solvents,370 and azoles371 have been carried out. Other studies include the secondary-ion mass spectra of nonvolatile silver complexes,372 the relationship between Lewis acid-base behavior in the gas phase and the aqueous solution,373 or the rates of hydride abstraction from amines via reactions with ground-state Ag+.374... 

The carboxyl functions in the new structures are buried within the clefts in a manner that discourages the formation of the intermolecular hydrogen bonded dimers which are usually observed in the solution and solid phases. Unusual acid-base behavior is one consequence. In the smallest system 11 (represented by the benzene spacer) a tremendous difference in pKa s (6 units) can be observed for the two ionizations 14). 

An early attempt to provide a framework to observations on the chemistry of substances that react in water to produce acids or bases was provided by S. A. Arrhenius. At that time, the approach was limited to aqueous solutions, and the definitions of an acid and a base were given in these terms. Of course we now know that acid-base behavior is not limited to these cases, but it applies much more broadly. If we consider the reaction between gaseous HC1 and water,... 

Acid-base behavior according to the Lewis theory has many of the same aspects as does acid-base theory according to the Bronsted-Lowry theory. 

The usual concerns about acid-base behavior (other than knowing in your soul that it really can t be very important) are where protons go if they re given a choice, how buffers work, and logarithms. Your professor s job is to try to convince you that acid-base behavior has a place in biochemistry. Your job is to learn it—just in case your professor is right. 

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