Oxygen metal reacting with

Beryllium Nitride. BeryUium nitride [1304-54-7], Be N2, is prepared by the reaction of metaUic beryUium and ammonia gas at 1100°C. It is a white crystalline material melting at 2200°C with decomposition. The sublimation rate becomes appreciable in a vacuum at 2000°C. Be2N2 is rapidly oxidized by air at 600°C and like the carbide is hydrolyzed by moisture. The oxide forms on beryllium metal in air at elevated temperatures, but in the absence of oxygen, beryllium reacts with nitrogen to form the nitride. When hot pressing mixtures of beryUium nitride and sUicon nitride, Si N, at 1700°C, beryllium sUicon nitride [12265-44-0], BeSiN2, is obtained. BeSiN2 may have appHcation as a ceramic material. 

Cobalt metal is significantly less reactive than iron and exhibits limited reactivity with molecular oxygen in air at room temperature. Upon heating, the black, mixed valence cobalt oxide [1308-06-17, Co O, forms at temperatures above 900°C the oHve green simple cobalt(II) oxide [1307-96-6] CoO, is obtained. Cobalt metal reacts with carbon dioxide at temperatures greater than 700°C to give cobalt(II) oxide and carbon monoxide. 

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). 

Table 20.2 lists the formulas of the oxides formed when the more common transition metals react with oxygen. With one exception (Cu20), the transition metal is present as a +2 and/or a +3 ion. In Co304 and in other oxides of general formula M304, there are two different types of cations +2 and +3. To be specific, there are twice as many +3 as +2 cations we might show the composition of Co304 as... 

The alkali metals are extremely reactive. Thus, there is a dramatic change in chemistry as we pass from the inert gases to the next column in the periodic table. The chemistry of the alkali metals is interesting and often spectacular. Thus, these metals react with chlorine, water, and oxygen, always forming a +1 ion that is stable in contact with most substances. The chemistry of these +1 ions, on the other hand, is drab, reflecting the stabilities of the inert gas electron arrangements that they have acquired. 

Competing reactions often consume some of the starting materials. For example, sodium metal reacts with water to produce sodium hydroxide. If a sample of oxygen is contaminated with water vapor, both O2 and H2 O will react with the sodium metal. The more water present in the gas mixture, the less Na2 O2 will be formed. 

Most corrosion processes in copper and copper alloys generally start at the surface layer of the metal or alloy. When exposed to the atmosphere at ambient temperature, the surface reacts with oxygen, water, carbon dioxide, and air pollutants in buried objects the surface layer reacts with the components of the soil and with soil pollutants. In either case it gradually acquires a more or less thick patina under which the metallic core of an object may remain substantially unchanged. At particular sites, however, the corrosion processes may penetrate beyond the surface, and buried objects in particular may become severely corroded. At times, only extremely small remains of the original metal or alloy may be left underneath the corrosion layers. Very small amounts of active ions in the soil, such as chloride and nitrate under moist conditions, for example, may result, first in the corrosion of the surface layer and eventually, of the entire object. The process usually starts when surface atoms of the metal react with, say, chloride ions in the groundwater and form compounds of copper and chlorine, mainly cuprous chloride, cupric chloride, and/or hydrated cupric chloride. 

Although it has been known since 19051 that very pure chromium metal reacts with acids, under oxygen-free conditions, to produce large quantities of chromium (II), this approach to the preparation of chromium(II) compounds has not been developed. Rather, syntheses generally involved (1) reduction of chro-mium(III), either by electrolytic means or by chemical agents (for example Zn/Hg), or (2) metathetical procedures. Both methods are inefficient and often lead to impure products. Recently2-8 extensive use of reactions between electrolytic chromium and various acids has led to the synthesis of a wide variety of chromium (II) complexes which would be considerably more difficult to prepare by other methods.9-11... 

When the oxygen compounds of group IA and IIA metals react with water, strongly basic solutions are produced regardless of whether an oxide, peroxide, or superoxide is involved. 

Although most metals react with oxygen to form oxides, the reactions of the group IA metals do not always give the expected products, as shown by the following equations ... 

The systems where this type of reaction is produced may be metal-, heme- or flavin-dependent. In flavin-dependent monooxygenases, a flavin-oxygen intermediate reacts with the substrate, producing water in a second step and requiring cofactors for regeneration of the flavin moiety. The non-heme-dependent oxygenases include the... 

The remaining alkali metals react with oxygen to form superoxides. 

The Law of Conservation of Mass states that the total mass remains unchanged. This means that the total mass of the atoms of each element represented in the reactants must appear as products. In order to indicate this, we must balance the reaction. When balancing chemical equations, it is important to realize that you cannot change the formulas of the reactants and products the only things you may change are the coefficients in front of the reactants and products. The coefficients indicate how many of each chemical species react or form. A balanced equation has the same number of each type of atom present on both sides of the equation and the coefficients are present in the lowest whole number ratio. For example, iron metal reacts with oxygen gas to form rust, iron(III) oxide. We may represent this reaction by the following balanced equation ... 

Metals react with nonmetals. These reactions are oxidation-reduction reactions. (See Chapters 4 and 18). Oxidation of the metal occurs in conjunction with reduction of the nonmetal. In most cases, only simple compounds will form. For example, oxygen, 02, reacts with nearly all metals to form oxides (compounds containing O2-). Exceptions are the reaction with sodium where sodium peroxide, Na202, forms and the reaction with potassium, rubidium, and cesium where the superoxides, K02, Rb02, and Cs02 form. 

Investigations of the generation of super base sites on alkaline earth metal oxides by doping with alkali metals (246,247,253) led to the inference that when zero-valent alkali metals react with a metal oxide surface, the electron donated by the alkali metal to the oxide lattice resides in a defect site, such as an oxygen vacancy, generating a one-electron donor site (F center) (254,255) (Scheme 40). 

The oxygen radicals get adsorbed on the catalyst surfaces and either combine to form oxygen or react with metal surfaces. This favors the decomposition reaction of H2O and enhances the hydrogen yield. To date the hydrogen yield and efficiencies are not high enough for practical application. 

Oxygen difluoride reacts with many common metals forming fluorides. The reaction stops when the metal surface is covered with a protective layer of fluoride ... 

Mention has already been made of the uciion of oxygen and oxidants on metal. It should be noted that metals react with sulfides, such as hydrogen sulfide, and are subsequently subject to additional slow attack by oxygen and oxidants. Thus, copper reacts to form sulfide and then the basic copper sulfate. 

Alkaline earth metals react with halogens to yield ionic halide salts, MX2, and with oxygen to form oxides, MO ... 

Chromium metal reacts with aqueous acids in the absence of oxygen to give Cr2+(aq), the beautiful blue chromium(II) (chromous) ion, in which Cr2+ is bound to six water molecules, Cr(H20)62+ (Figure 20.7a) ... 

---