Alkaline earth metals superoxides

The superoxides are ionic soHds containing the superoxide, O - A comprehensive review of the superoxides was pubHshed ia 1963 (109) they are described ia Reference 1. Superoxides of all of the alkaU metals have been prepared. Alkaline-earth metals, cadmium, and 2iac all form superoxides, but these have been observed only ia mixtures with the corresponding peroxides (110). The tendency to form superoxides ia the alkaU metal series iacreases with increasing size of the metal ion. 

In addition to the oxides MO, peroxides MO2 are known for the heavier alkaline earth metals and there is some evidence for yellow superoxides M(02)2 of Ca, Sr and Ba impure ozonides Ca(03)2 and Ba(03)2 have also been reported. As with the alkali metals, stability... 

Note from Table 20.1 that several different products are possible when an alkali or alkaline earth metal reacts with oxygen. The product may be a normal oxide (O2 ion), a peroxide (022- ion), or superoxide (02 ion). 

Superoxides, and Ozonides of Alkali and Alkaline Earth Metals , Plenum Press, NY (1966)... 

Vol nov, I. I. Peroxides, superoxides, and ozonides of alkali and alkaline earth metals. New York Plenum Press 1966. 

I. I. Vol nov, Peroxides, Superoxides, and O nides, ofMlkali and Alkaline Earth Metals, Plenum Publishers Corp., New York (1966). 

Alkali- (and alkaline-earth) metal solutions of liquid ammonia display some bizarre properties that can be accounted for in terms of solvated electrons. The solvated electron is an excellent one-electron reducing agent and can be used to produce peroxides, superoxides, and metals with negative oxidation states. Compounds involving crown ethers and cryptands of the alkali metals in ammonia and related solvents yield the very rare electrides and alkalides. 

VoTnov, II (1964) Woroncow J (trans) Petrocelh AW (ed) (1966) Peroxides, superoxides and ozonides of alkah and alkaline earth metals. Plenum, New York Edwards JO (ed) (1962) Peroxide reaction mecharrisms. Wiley, New York Machu W (1951) Das Wasserstoffperoxyd und die Perverbindrmgen. Springer, Berlin Heidelberg New York... 

A systematic study of oxygen compounds is generally done in conjunction with the study of the other elements. Thus, the oxides of boron were considered in the discussion of boron chemistry in Chapter 21 the oxides of carbon were also considered there. The survey of the chemistry of the alkali and alkaline earth metals in Chapter 21 provided an opportunity to describe normal oxides, peroxides, and superoxides and the important oxides of sulfur, nitrogen, and phosphorus are discussed in this chapter. 

Lattice energies, alkali metal salt values, amides and, 196 azides and, 198-199 bifluorides and, 199 borofluorides and, 203 borohydrides and, 197 chalcogenides and, 192,193 cyanates and, 199-200 cyanides and, 196-197 halides and, 189, 190 hydrides and, 189, 191, 192 hydrosulfides and, 195-196 hydroxides and, 192,194, 195 nitrates and, 201 superoxides and, 197-198 thiocyanates and, 200 alkaline earth salt values, acetylides and, 198 carbonates and, 202-203 chalcogenides and, 192, 193 imides and, 196 peroxides and, 198 calculation uses, absolute enthalpies and, 206 electron affinity determination and, 203-204... 

Superoxides. The action of oxygen at pressures near atmospheric on K, Rb or Cs gives yellow to orange crystalline solids of formula MOz. Na02 can be obtained only by reaction of Na202 with 02 at 300 atm and 500°. Li02 cannot be isolated and the only evidence for it is the similarity in the absorption spectra of the pale yellow solutions of Li, Na and K on rapid oxidation of the metals in liquid ammonia at —78° by oxygen. Alkaline-earth, Mg, Zn and Cd superoxides occur only in small concentrations as solid solutions in the peroxides. Tetramethylammonium superoxide has been obtained as a yellow solid (m.p. 97°), which dissolves in water with evolution of 02. There is clearly a direct correlation between superoxide stability and electropositivity of the metal concerned. 

Of course, once the ore is obtained from its deposit, the actual work of extracting the desired metal has yet to be accomplished. In addition to metals, a variety of other substances comprise natural minerals. Since aluminum and silicon are the most prevalent elements in the Earth s crust, most of the metals exist naturally as aluminates, silicates, or aluminosilicates. The most common minerals are feldspars and clays. These materials have been used since ancient times for the production of materials such as pottery, brick, and china. An example of a feldspar is K2Al2Si60i6, which corresponds to a mixture of potassium superoxide, alumina, and silica (K20-Al203 6Si02). Upon contact with water and carbon dioxide, a weathering reaction results in kaolinite, an aluminosilicate clay (Eq. 1). However, in addition to these oxidized sources of metals, there are substances such as alkaline carbonates, sulfates, phosphates, as well as organic matter that need to be removed to yield the desired metal. As you would expect, the yield for this process is quite low ores typically possess less than 1 % of the desired metal ... 

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