Acid strength of oxoacids

The Dependence of Acid Strengths of Oxoacids on the Oxidation State of the Central Element... 

The acid strength of oxoacid salts in the solid state increases with the electronegativity of the metal ion, and hence catalytic activity increases with electronegativity. Figure 14 shows an example of selectivity, in which the selectivity of double bond isomerization of butene over metal sulfates changes with the electronegativity. ... 

The acid strength of nonmetal hydrides increases towards the right and to the bottom of the periodic table. Acid strengths of oxoacids can be predicted approximately from their formulae by Pauling s rules. Metal cations with polarizing character are acidic in water, and some form amphoteric oxides or hydroxides. 

All oxoacids have the acidic H atom bonded to an 0 atom, so bond strength (length) is not a factor in their acidity, as it is with the nonmetal hydrides. Rather, two factors determine the acid strength of oxoacids the electronegativity of the central nonmetal (E) and the number of 0 atoms. 

Oxoacid (continued) acid strength of, 567-568 oxidizing strength, 568-570 reducing strength of, 568-570 Oxoacids, 42... 

The interhalogens have properties intermediate between those of the constituent halogens. Nonmetals form covalent halides metals tend to form ionic halides. The oxoacids of chlorine are all oxidizing agents both acidity and oxidizing strength of oxoacids increase as the oxidation number of the halogen increases. 

Two comparisons are discussed in this section (a) the acid strengths of the oxoacids of the second period, H3B03, H2C03 and HN03, and (b) those of the oxoacids of the third period, H3P04, H2S04 and HC104. 

For oxoacids that contain the same number of OH groups and the same number of O atoms, acid strength increases as the electronegativity of Y increases. For example, the acid strength of the hypohalous acids HOY (Y = Cl, Br, or I) increases as the electronegativity of the halogen increases ... 

Likewise, carbonic acid CO(OH)2 is rather unstable with respect to C02 and water since the very strong bonds in COz are resistant to addition. But the CO3- and HCOf ions are stabilised by resonance. The relative strengths of oxoacids in aqueous solution are evidently dependent on the stabilities of their conjugate bases, in which resonance (electron de-localisation) appears to play some part. 

The acid strength of metallic salts of oxoacids in the solid state (and hence the catalytic activity by acid catalysis) increases with electronegativity of the metal ion. ... 

The strength of oxoacids with a given central element X increases with the number of lone oxygen atoms attached to the central atom. If the formula of these acids is written as XO (OH) the corresponding acid strengths fall into distinct classes according to the value of n, the number of lone oxygen atoms (see... 

Various trends have long been noted in the acid strengths of many binary hydrides and oxoacids. Values for some simple hydrides are given in Table 3.4 from which it is clear that acid strength increases with atomic number both in any one horizontal period and in any... 

The strength of an acid depends on its ability to donate a proton, which depends in turn on the strength of the bond to the acidic proton. In this section, we apply trends in atomic and bond properties to determine the trends in acid strength of nonmetal hydrides and oxoacids and discuss the acidity of hydrated metal ions. 

Figure 18.12 The relative strengths of oxoacids. A, Among these hypohalous acids, HOCl is the strongest and HOI the weakest Because Cl is the most electronegative of the halogens shown here, it withdraws electron density (indicated by thickness of green arrow) from the O—H bond most effectively, making that bond most polar in HOCl (indicated by the relative sizes of the 5 symbols). B, Among the chlorine oxoacids, the additional O atoms in HOCIO3 pull electron density from the O—H bond, making the bond much more polar than that in HOCl.

Understand how electronegativity and bond length, polarity, and strength affect the acid strength of nonmetal hydrides and oxoacids, and explain why certain metal ions form acidic solutions ( 18.6) (EPs 18.68-18.75)... 

Consider the adds where Y is Cl. The Cl atom becomes effectively more electronegative as more 0 atoms are attached to it. As a result, the 0 atom bonded to the H atom becomes effectively more electronegative, so attracts electrons more easily the H atom then becomes more acidic.Thus, HCIO4 has the greatest acid strength of this series of oxoacids. 

Our network of ideas can be applied to oxides, which divide into metal ionic and nonmetal covalent types. Ionic oxides are basic anhydrides that produce metal hydroxides and hydroxide ions in aqueous solution. Nonmetal oxides are acidic anhydrides that produce oxoacids and hydronium ions in solution. These correlations have become the sixth component of our network of ideas. The relative strengths of oxoacids and hydroacids can be rationalized by using other parts of the network. A systematic approach to the nomenclature of the oxoacids is based on the five representative -ic acids. 

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