Acidity of oxyacids

More important for inorganic oxyacids is the number of oxygen atoms surrounding the central atom. Thus in the series of chlorine oxyacids. acid strength increases in the order HOCI < HOClO < H0C102 <- HOClOj. The trends in acidity of oxyacids, and even reasonably accurate predictions of their pKu values, can be obtained from 19... 

The acidity of oxyacids increases with increasing eiectronegativity of the haiogen atom... 

HCIO, is a stronger acid than iodic(i) acid, HIO (Figure 18.5). The acidity of oxyacids increases... 

The chemist is much concerned with the relationship between the structure and reactivity of substances. A knowledge of such a relationship enables the chemist to make new compounds which have certain desired properties. The Brdnsted acid-base reaction is a common and relatively simple reaction we therefore use it to discuss the relationship of structure and reactivity. We here restrict our discussion to the oxyacids and oxyanions. We will first present the facts about reactivity, and then we will present a broad concept to rationalize the relative reactivities. The acidity of oxyacids follows periodic patterns and is also influenced by the oxidation number of the central atom. 

Chlorine forms a number of oxyacids. Which of the following is the correct order of increasing acid strength ... 

The literature on metal complexes of carbohydrates through 1965 has been fully reviewed by Rendleman (I), and we shall therefore only discuss recent work. We shall not discuss the complexes formed with strong bases, such as calcium and barium oxide these are salts in which the sugar acts as a weak acid, losing one or several protons. Nor shall we discuss the complexes formed with anions of oxyacids—e.g., borate, stannate, periodate, etc. ions all these are compounds formed by covalent bonds in alkaline solution. We are concerned only with complexes formed with cations in neutral aqueous solution there is no evidence for the formation of complexes between sugars and simple anions in neutral aqueous solution. (For an example of complex formation between a sugar derivative and chloride ion in chloroform solution, see Reference 3.)... 

It is generally true that for a series of oxyacids of the same element (e.g., HCIO4, HCIO3, HC102, and HOC1), the acid containing the element in the highest oxidation state will be the... 

Sulfur, selenium, and tellurium form a variety of oxyacids. Certain of these compounds and their derivatives are of great importance, with the most important of all these compounds being sulfuric acid. Because of the extraordinary significance of that compound, it will be described in more detail in a separate section. The major oxyacids of sulfur are shown in Table 15.6. Differences between the sulfur oxyacids and those of selenium and tellurium will be discussed later. 

Silicic acid. Any oxyacid of silicon, such as orthosilicic acid, H4SK>4, meta-silicic acid, H2Si03. These substances are hypothetical compounds inferred from their metallic or organic derivatives. 

Platinum and gold are regarded as unattackable metals because they are nearly always in the passive state. A gold anode dissolves in neutral or acid chloride solutions at very low c.d. s to form Au " + ions at a potential of about + 1.2 volts as the current is increased, however, the potential rises rapidly to + 1.7 volts, the electrode ceases to dissolve and chlorine is evolved instead. Platinum is actually less noble than gold, but it is rendered passive much more easily, especially in solutions of oxyacids if the electrolyte contains ammonia or hydrochloric acid, however, platinum suffers appreciable anodic attack, particularly if the metal is in a finely-divided form. 

A wide range of oxyacids is possible with more than one sulfur atom. Although the acids are not always very stable, the oxyanions are often more easily prepared. Many of these are likely intermediates in the oxidation of aqueous sulfites and occur at low concentration in water droplets in the atmosphere. Higher concentrations of sulfur oxyanions such as 8406, SsO , and S Ol can be found in mineralized acid-sulfate waters of volcanic crater lakes (e.g., Sriwana et al, 2000). 

In the series of oxyacids of chlorine, the acid strength in aqueous solution is in the order HCIO4 > HCIO3 > HCIO2 > HOCl... 

Water solutions of some molecules are acidic and are named as acids. Acids are important compounds with specific properties that will be discussed at length in Chapter 19. If the compound produces hydrogen ions (H+) in solution, it is an acid. For example, HCl produces H+ in solution and is an acid. Two common types of acids exist— binary acids and oxyacids. 

According to the Bronsted—Lowry deHnition (Section 2.7), an cicid is any substance that donates H. Altiioi h we usually think of oxyacids (H2SOJ, HNOj) or halogen acid.s (HC1, HBr) in this context, any compound containing a hydrc en atom can be an add under the ri t circumstances. By measuring dissociation constants of dilFerent adds and expressii the results as pX, values, an acidity order can be established. Recall from Section 2.8 that a low pK corresponds to a strong add, and a high pK corresponds to a weak acid. 

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