Solid oxidizing agents

Other factors have been identified as rate controlling in other types of solid—solid interaction, and some of these are described in subsequent sections. These include, for example, the decomposition of a solid catalyzed by a (different) solid and rate processes in which one reactant is volatilized, e.g. reaction of carbon (-> C02) with a solid oxidizing agent. 

Strontium Hydride. SrH2 mw 89.64 hygr white cryst solid mp 675° (decompn) bp, sublimes at 1000° (in Hj) d 3.27g/cc. The hydride is vigorously decompd by hot and cold w and moderately so by ethanol to liberate H2. Prepn is by hydrogenation of oxide-free Sr at 200-1000°. Mixts of SrHj with solid oxidizing agents, such as chlorates, perchlorates or chromates, will react explosively if heated slowly Refs 1) Gmelin, Syst Nr 9 (1960), 150-51... 

Mixing of flammable materials and combustible solids with strong oxidizing agents ... 

Isoindoles are reactive toward oxidizing agents, and precautions usually advocated in the preparation of these compounds to prevent their oxidation merit careful consideration. The end products of oxidation are most often colored, resinous materials of indeterminate structure. The oxidative reactions appear to be accelerated by light and occur much more rapidly in solution than in the solid state. In a separate but possibly related process, certain isoindoles undergo polymerization in the solid state to give resins which, according to... 

Fig. 1.40 Schematic anodic polarisation curve for a passivatable metal (solid line), shown together with three alternative cathodic reactions (broken line). Open-circuit corrosion potentials are determined by the intersection between the anodic and cathodic reaction rates. Cathode a intersects the anodic curve in the active region and the metal corrodes. Cathode b intersects at three possible points for which the metal may actively corrode or passivate, but passivity could be unstable. Only cathode c provides stable passivity. The lines a, b and c respectively could represent different cathodic reactions of increasing oxidizing power, or they could represent the same oxidizing agent at increasing concentration.

The Cr2072- ion can act as an oxidizing agent in the solid state as well as in water solution. In particular, it can oxidize the NH ion to molecular nitrogen. When a pile of ammonium dichromate is ignited, a spectacular reaction occurs (Figure 20.12). 

Of the four halogens, iodine is the weakest oxidizing agent. Tincture of iodine, a 10% solution of I2 in alcohol, is sometimes used as an antiseptic. Hospitals most often use a product called povidone-iodine, a quite powerful iodine-containing antiseptic and disinfectant, which can be diluted with water to the desired strength. These applications of molecular iodine should not delude you into thinking that the solid is harmless. On the contrary, if I2(s) is allowed to remain in contact with your skin, it can cause painful bums that are slow to heal. 

These reactions show sulfur in the role of an oxidizing agent. The properties of compounds such as ZnS suggest they contain the sulfide ion, S-2. The formation of this ion again can be expected on the basis of the fact that the neutral sulfur atom has two electrons less than enough to fill the valence orbitals. Acquisition of two electrons completely fills the low energy valence orbitals and solid ionic compounds can be formed. 

In most of its compounds nickel has a +2 oxidation number, but it is possible to get a higher state by heating Ni(OH)2 with hypochlorite ion in basic solution. Hypochlorite ion, CIO-, is one of the stronger oxidizing agents at our disposal in basic solution. There is considerable argument about the formula of the black solid that is formed, but we shall label it as Ni208 and write the equation... 

Acid or base hydrolysis with rate decreasing with mw increase dil NaOH decomposes acids yielding 02 dimeric as solids H-bonded hr soln pure liq and vap state most powerful oxidizing agents of all peroxides, decompd by irradiation... 

It is a powerful oxid agent which reacts vigorously with reducing matls Tests. It absorbs infrared radiation in so In at 3270—3250cm"1 and as a solid at 3260— 3232cm"1 (Ref 7)... 

HGURE 15.16 Sulfuric acid is an oxidizing agent. When some concentrated acid is poured on solid sodium bromide, NaBr, the bromide ions are oxidized to elemental bromine, which colors the mixture red-brown. 

One spectacular example of the oxidizing ability of perchlorates is their use in the booster rockets of space shuttles. The solid propellant consists of aluminum powder (the fuel), ammonium perchlorate (the oxidizing agent as well as a fuel), and iron(III) oxide (the catalyst). These reactants are mixed into a liquid polymer, which sets to a solid inside the rocket shell. A variety of products can form when the mixture is ignited. One of the reactions is... 

Cross-hnked polyacrylamides are a group of hydrophihc solid supports introduced primarily for preparation of biopolymers (Fig. 4). Unhke PS resins, polyacrylamides have excellent swelling capacity in both protic (water, alcohols) and aprotic (dichloromethane, dimethylformamide) solvents [88]. These beads are stable towards bases, acids, and weak reducing and oxidizing agents [89]. Predictably, conditions under which amide bonds are cleaved (i.e., sodium in liquid ammonia) [90] lead to rapid decomposition of the polymer. 

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