Hydroxides and oxides

Although all of the Group IA and HA metals will react with oxygen, there is considerable variation in the ease of the reactions and the nature of the products. Chapter 4 described how the reaction of oxygen with the Group LA metals produces a normal oxide only in 

Sodium reacts with oxygen to produce a peroxide, 

To some extent, the products can be mixtures of oxides with the composition depending on the reaction conditions. 

At least part of the stabilization of the compounds containing the diatomic anions 022- and 02 comes from the fact that crystal lattices are most stable when the cations and anions have similar sizes (see Chapter 5). The Group IIA metals give normal oxides except for barium and radium, which give peroxides when they react with oxygen  

Oxides of metallic elements typically react with water to produce hydroxides. In the case of the oxides of the Group IA elements, the reactions are 

The chloride can be crystallized but the bromide disproportionates. On the basis of mol wt and infrared spectroscopic evidence the proposed structure is  

The oxides MO are best obtained by calcining the carbonates (pp. 114 and 122) dehydration of the hydroxides at red heat offers an alternative route. BeO (like the other Be chalcogenides) 

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 

COODENOUOH and V. A. Stenoer, Magnesium, calcium, sironiium, barium and radium, Comprehen.uve inorganic Chemistry., Vol. 1, pp. 591 -664 (197.3). 

Beryllium, Magnesium, Calcium, Strontium, Barium and Radium 

In the vapour state, alkali metal halides are present mainly as ion-pairs, but measurements of M—X bond distances and electric dipole moments suggest that covalent contributions to the bonding, particularly in the lithium halides, are important. 

Magnetic studies on the co-precipitated hydroxides of Cd , Fe , and Ni have been performed, the ferrites Cd Fei.. [Nii Fei +, ]04, showing characteristic properties in which the primary ferromagnetism is due to 7-Fe203.3  

What is the composition of litharge, massicot, lead(IV) oxide, and minium Under what conditions do they form What is their structure What are the oxidation states of lead in these oxides  

Put a small amount of lead(II) oxide into one test tube, of lead IV) oxide into a second one, and of minium into a third one. Pour 

3-5 ml of concentrated hydrochloric acid into each of the tubes. Stir their contents and heat them. What do you observe What gas evolves. Write the equations of the reactions. What properties do lead(IV) oxide and minium exhibit in this reaction  

Perform a similar experiment, using a 10% nitric acid solution instead of the hydrochloric acid. Write the equations of the reactions. 

Introduce 0,5 g of lead(IV) oxide into a 0.1 N manganese sulphate solution acidified with a 10 % sulphuric acid solution and heat it. Let the precipitate settle. What is the change in the solution s colour due to Write the equation of the reaction. Will a similar reaction proceed with lead(II) oxide and minium  

In many inorganic pigments, lanthanides and transition elements are responsible for color. Metal oxides and oxide hydroxides are, however, also important as colored pigments because of their optical properties, low price, and ready availability. Colored pigments based on oxides and oxide hydroxides are either composed of a single component or mixed phases. In the latter, color is obtained by incorporation of appropriate cations. 

The continually increasing importance of iron oxide pigments is based on their nontoxicity, chemical stability, wide variety of colors ranging from yellow, orange, red, brown, to black, and good performance/price ratio. Natural and synthetic iron oxide pigments consist of well-defined compounds with known crystal structures (Table 3.1) [3.1, 3.2]. 

Industrial Inorganic Pigments. Edited by G. Buxbaum and G. Pfaff Copyright 2005 WILEY-VGH Verlag GmbH Co. KGaA, Weinheim ISBN 3-527-30363-4 

Y-FeOOH lepidocrocite 12022-37-6 boehmite color changes with increasing particle size from yellow to orange 

Y-Fe203 maghemite 12134-66-6 ordered spinel ferrimagnetic color brown 

What shape for the gas-phase molecule SrF2 is consistent with VSEPR theory  

The valence shell of Sr in Srp2 contains two bonding pairs of electrons and no lone pairs, therefore, by VSEPR theory Srp2 should be a linear molecule. 

For which of the following gas-phase species is VSEPR theory 

Magnesium chloride, bromide and iodide crystallize from aqueous solution as hydrates which undergo partial hydrolysis when heated. The anhydrous salts are, therefore, prepared by reaction 11.18. 

A hygroscopic solid absorbs water from the surrounding air but does not become a liquid. 

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Boron trioxide is not particularly soluble in water but it slowly dissolves to form both dioxo(HB02)(meta) and trioxo(H3B03) (ortho) boric acids. It is a dimorphous oxide and exists as either a glassy or a crystalline solid. Boron trioxide is an acidic oxide and combines with metal oxides and hydroxides to form borates, some of which have characteristic colours—a fact utilised in analysis as the "borax bead test , cf alumina p. 150. Boric acid. H3BO3. properly called trioxoboric acid, may be prepared by adding excess hydrochloric or sulphuric acid to a hot saturated solution of borax, sodium heptaoxotetraborate, Na2B407, when the only moderately soluble boric acid separates as white flaky crystals on cooling. Boric acid is a very weak monobasic acid it is, in fact, a Lewis acid since its acidity is due to an initial acceptance of a lone pair of electrons from water rather than direct proton donation as in the case of Lowry-Bronsted acids, i.e. 

Salts containing and HO anions are named oxide and hydroxide, respectively. Anions are cited in alphabetical order which may be different in formulas and names. 

Minimizing Spectral Interferences The most important spectral interference is a continuous source of background emission from the flame or plasma and emission bands from molecular species. This background emission is particularly severe for flames in which the temperature is insufficient to break down refractory compounds, such as oxides and hydroxides. Background corrections for flame emission are made by scanning over the emission line and drawing a baseline (Figure 10.51). Because the temperature of a plasma is... 

Gallium Oxides. The preparation conditions of gallium oxides and hydroxides are Hsted iu Table 6. 

Oxides and hydroxides react with HCl to form a salt and water as in a simple acid—base reaction. However, reactions with low solubiHty or insoluble oxides and hydroxides is complex and the rate is dependent on many factors similar to those for reactions with metals. Oxidizing agents such as H2O2, H2SeO, and V2O3 react with aqueous hydrochloric acid, forming water and chlorine. 

The mechanism and rate of hydrogen peroxide decomposition depend on many factors, including temperature, pH, presence or absence of a catalyst (7—10), such as metal ions, oxides, and hydroxides etc. Some common metal ions that actively support homogeneous catalysis of the decomposition include ferrous, ferric, cuprous, cupric, chromate, dichromate, molybdate, tungstate, and vanadate. For combinations, such as iron and... 

The coating composition is a combination of hydrated chromium and aluminum oxides and hydroxides, eg, Cr202 XH2O, x — 1, 2. 

Hydrolysis. The surfaces of metal oxides and hydroxides can take up or release or OH ions and become charged. Potentials as high as 100 mV may be sustained ia aqueous solutions. For aqueous solutions this is a function of the pH the zeta potential for the particle is positive if the solution pH is below the particle s isoelectric pH (pH ), and negative if the pH is above pH Isoelectric poiats for metal oxides are presented ia several pubheations (22,23). Reactions of hydroxyl groups at a surface, Q, with acid and base may be written as follows ... 

G. A. Parks, Chem. Revs. 65, 177—198 (1965). A comprehensive list of isoelectric points for soHd oxides and hydroxides. 

From Metal Oxides and Hydroxides This reaction is usually an equihbrium ia which the water must be removed by physical or chemical... 

K. Wefers and C. Misra, Oxides and Hydroxides ofMluminum, Mlcoa Technical Paper No. 19, revised, Alcoa Laboratories, Alcoa Division, Aluminum... 

Oxides and Hydroxides. ThaHous oxide is most readily obtained by dehydration of TlOH ia high vacuum at 50°C. It is black, crystalline, and hygroscopic. It reacts with water to form the hydroxide and dissolves ia ethanol to yield the ethoxide (9). 

Triorganotin oxides and hydroxides are moderately strong bases and react readily with a wide variety of acidic compounds ... 

Hydrous Oxides and Hydroxides. Hydroxide addition to aqueous zirconium solutions precipitates a white gel formerly called a hydroxide, but now commonly considered hydrous zirconium oxide hydrate [12164-98-6], 7 0 - 112 0. However, the behavior of this material changes with time and temperature. 

Cavity. A fluid-filled cavity is sometimes present beneath the core (Fig. 3.3). The cavity may be huge as in Fig. 3.8 or small as in Fig. 3.9. The cavity may result, in part, from acidic conditions internally. Acid conditions may prevent precipitation of oxides and hydroxides inside the tubercle. 

Oxygen corrosion only occurs on metal surfaces exposed to oxygenated waters. Many commonly used industrial alloys react with dissolved oxygen in water, forming a variety of oxides and hydroxides. However, alloys most seriously affected are cast irons, galvanized steel, and non-stainless steels. Attack occurs in locations where tuberculation also occurs (see Chap. 3). Often, oxygen corrosion is a precursor to tubercle development. 

Sulfides are intermixed with iron oxides and hydroxides on carbon steels and cast irons. The oxides are also produced in the corrosion process (Reaction 6.6). Although theoretical stoichiometry of 1 to 3 is often suggested between sulfide and ferrous hydroxide, empirically the ratio of iron sulfide to ferrous hydroxide is highly variable. Sulfide decomposes spontaneously upon exposure to moist air. Additionally, corrosion-product stratification is marked, with sulfide concentration being highest near metal surfaces. 

Normal mill coolant pH was near 5. The upset caused large amounts of iron corrosion products to be swept into the coolant. Settling of iron oxides and hydroxides fouled many mill components. 

The isocyanates are believed to aid wetting of metals by interacting with the metal oxides and hydroxides (M-OH) present on the surface. The isocyanates can then react with water to form a rigid polyurea network which interacts at the metal surface through hydrogen bonding. The isocyanates also react to form hard segments , which will be explained shortly. 

Steam), and oi er input from CORCON. It contains a library of thermodynamic properties je energies from bich vapor pressures are calculated) for chemical species (mostly elements, oxides, and hydroxide that might be formed by fission products and other melt constituents. 

Dehydrofluorination by primary and secondary aliphatic amines occurs at room temperature and is the basis of diamine cross linkmg, which occurs by dehydrofluonnation and subsequent nucleophihc substitution of the double bond The locus of dehydrofluonnation is a VDF unit flanked by two perfluoroolefin units This selectively base-sensitive methylene group also undergoes elimination as the first step in phase-transfer-catalyzed cross-hnking with quaternary ammo mum or phosphomum salts, bisphenols, and morganic oxides and hydroxides as HF acceptors [31, 32]... 

Hydrogen fluoride reacts witlr metal carbonates, oxides, and hydroxides. Accumulation of these fluoride compounds can render valves and other close-fitting moving parts inoperable in a process system, causing possible equipment or process failures. Hydrogen fluoride also attacks glass, silicate ceramics, leather, natural rubber, and wood, but does not promote their combustion. 

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