Halogen oxides and oxoacids

Most halogen oxides are liable to decompose, often explosively, on heating or under the influence of shock or impact. This is especially so in the case of chlorine and bromine oxides, all of which have positive values of AH and AGP at room temperature. 

V What does this tell you about their stability  

The structure, melting temperatures (Tn,) and boiling temperatures (Tb) of the three most important oxides of chlorine CI2O, CIO2 and CI2O7. 

1 Dichlorine monoxide, chiorine dioxide and dichiorine heptoxide 

The gas explodes on heating, giving chlorine and oxygen. An especially violent explosion occurs if the gas is mixed with ammonia, or if the liquid makes contact with rubber. 

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The Group 7A(17) elements form many ionic and covalent compounds metal and nonmetal halides, halogen oxides, and oxoacids. Like the alkali metals, the halogens have an electron configuration one electron away from that of a noble gas whereas a 1A metal atom must lose one electron, a 7A nonmetal atom must gain one. It fills its outer level in either of two ways ... 

Discuss key features of Group 7A(17), understand how inter-molecular forces and the ns np configuration account for physical and chemical properties, and describe the halogen oxides and oxoacids ( 14.8) (EPs 14.68-14.75)... 

Oxidation A half-reaction in which there is an increase in oxidation number, 88 chromium, 548 electrolysis and, 498 fluorine, 557 halogens, 557-558 oxoacids, 568-570 oxoanions, 568-570 species strength, 506-507q transition metals, 546t zinc, 86-87... 

The acid strengths and oxidizing abilities of the halogen oxoacids increase with the oxidation number of the halogen. The hypohalous acids, HXO (halogen oxidation number +1), are prepared by direct reaction of the halogen with water. For example, chlorine gas disproportionates in water to produce hypochlorous acid and hydrochloric acid ... 

A large number of binary halogen oxides are known, from shock-sensitive liquids to rather stable solids. Similarly, a large number of oxoacids and oxoacid salts are also known. 

Most halogen oxides are not very stable and decompose easily. This stems from the fact that the number of electrons in these molecules is an odd number. Therefore, the ions formed by the addition of an electron, whether in oxoacids or in oxoacid salts, are more stable. 

The oxoacids and their salts are very stable, in contrast to the lack of stability of the halogen oxides themselves. A large number of these acids exist at the representative oxidation states of the halogens, namely, +1, +3, +5, and +7. Even perbromic acid, HBr04, has been synthesized by fluorination ofbromates. 

Most halogen oxides are of low stability, but several oxoacids are known except for fluorine. Redox stability depends on pH, Cl2 and Br2 disproportionating in alkaline... 

Let s examine the compounds the halogens form with hydrogen and with each other, as well as their oxides, oxoanions, and oxoacids. 

Halogen Oxides, Oxoacids, and Oxoanions The Group 7A(17) elements form many oxides that are powerful oxidizing agents. Dichlorine monoxide (CI2O), chlorine dioxide (CIO2, with an unpaired electron and Cl in the unusual -t-4 oxidation state), and dichlorine heptaoxide (CLOy) are important examples. 

Halogen oxides are typically not very stable, and some oxygen compounds form as oxoacids instead (with the exception of fluorine there are no oxoac-... 

The halides of the elements have been surveyed throughout our tour of the representative elements. Common methods to prepare them include (1) direct reaction of the elements, (2) reactions of oxides or hydroxides with hydrogen halides, (3) reactions of oxides or lower halides with covalent fluorides, and (4) halogen exchange reactions. Nonmetal halides usually hydrolyze to form the corresponding hydroxide, oxide, or oxoacid. Pseudohalides are anions that resemble halides in their chemical behavior. 

For oxoacids with the same number of oxygen atoms, the oxidizing and acid strength both increase as the electronegativity value of the halogen increases. The general mles for the aeid strength of oxoacids are summarized in Section 12.10 of the text. 

More detailed consideration of these various equilibria and other redox reactions of the halogen oxoacids will be found under the separate headings below. As expected, the rates of redox reactions of the halogen oxyanions will depend, sometimes crucially, on the precise conditions used. However, as a very broad generalization, they tend to become progressively faster as the oxidation state of the halogen decreases, i.e. ... 

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. 

The acid strengths and oxidizing abilities of the halogen oxoacids (Table 15.8) increase with the oxidation number of the halogen. The... 

The greater the number of yf I oxygen atoms, the higher the oxidation state of the halogen and the stronger the oxoacid. 

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