Potassium reaction with oxygen

A number of chemiluminescent reactions may proceed through unstable dioxetane intermediates (12,43). For example, the classical chemiluminescent reactions of lophine [484-47-9] (18), lucigenin [2315-97-7] (20), and transannular peroxide decomposition. Classical chemiluminescence from lophine (18), where R = CgH, is derived from its reaction with oxygen in aqueous alkaline dimethyl sulfoxide or by reaction with hydrogen peroxide and a cooxidant such as sodium hypochlorite or potassium ferricyanide (44). The hydroperoxide (19) has been isolated and independentiy emits light in basic ethanol (45). 

Oxychlorination of Ethylene to Dichloroethane. Ethylene (qv) is converted to dichloroethane in very high yield in fixed-bed, multitubular reactors and fluid-bed reactors by reaction with oxygen and hydrogen chloride over potassium-promoted copper(II) chloride supported on high surface area, porous alumina (84) ... 

This reaction of an ionic hydride with water is a redox reaction because the hydride reduces the water (4-1 oxidation state for H) to H2 (0 oxidation state). In turn, the hydride (—1 oxidation state for H) is oxidized to H2. In general, ionic hydrides are good reducing agents. Some, such as potassium hydride, catch fire in air because of a rapid redox reaction with oxygen ... 

Keeping in mind the way sodium and potassium react with oxygen and air, predict the reaction of sodium and potassium with dilute acids Which metals do not react with dilute or concentrated acids ... 

Effects of Potassium on Ammonia Synthesis Kinetics Extensive research has been completed in which the effects of potassium on ammonia synthesis over iron single-crystal surfaces of (111), (100), and (110) orientations [59] have been determined. The apparent order of ammonia and hydrogen for ammonia synthesis over iron and K/Fe surfaces has been determined in addition to the effect of potassium on the apparent activation energy Ef) for the reaction. In all the experiments, potassium was coadsorbed with oxygen because only about 0.15 ML of potassium coadsorbed with oxygen is stable under ammonia synthesis conditions (20... 

In most formulas for potassium nitrate-based flitter effects, the sulfur content of the stars will be found to be below the stoichiometric requirements for the formation of sulfide from all of the potassium nitrate. In most of the formulas of this type there is insufficient carbon to perform the total reduction of the potassium nitrate to form sulfides. Potassium nitrate can react with sulfur to produce sulfate directly and this is common in flitter effects. In all cases flitter effects will be found to have insufficient molten sulfide melts to protect the aluminum from direct reaction with oxygen from air. A thin layer of potassium sulfide at the melting point is quickly oxidized and thus there is rapid loss of the sulfur content. A thin layer of potassium sulfide on aluminum is insufficient to cause delay. The oxidation of the aluminum takes place first through a rate moderating oxygen transport system liquid layer covering the aluminum and then must later take place within the solid jacket of potassium aluminate that forms over the aluminum. This explains the observation that most flitter sparks lose incandescence in a smooth decent of temperatures at the end of their burn. This can also explain why some formulas appear to produce sparks at more than one temperature. Adjustment of flitter effects is easily made with an understanding of the phenomenon involved. 

In this chapter we have seen that the reaction of potassium metal with oxygen leads to a product that we might not expect, namely, potassimn superoxide, K02(s). Let s design some experiments to learn more about this unusual product. 

Write balanced equation(s) for the reaction of potassium metal with oxygen gas. 

Reactions of the Hydroxyl Group. The hydroxyl proton of hydroxybenzaldehydes is acidic and reacts with alkahes to form salts. The lithium, sodium, potassium, and copper salts of sahcylaldehyde exist as chelates. The cobalt salt is the most simple oxygen-carrying synthetic chelate compound (33). The stabiUty constants of numerous sahcylaldehyde—metal ion coordination compounds have been measured (34). Both sahcylaldehyde and 4-hydroxybenzaldehyde are readily converted to the corresponding anisaldehyde by reaction with a methyl hahde, methyl sulfate (35—37), or methyl carbonate (38). The reaction shown produces -anisaldehyde [123-11-5] in 93.3% yield. Other ethers can also be made by the use of the appropriate reagent. 

Potassium superoxide is produced commercially by spraying molten potassium iato an air stream, which may be enriched with oxygen. Excess air is used to dissipate the heat of reaction and to maintain the temperature at ca 300°C. It can also be prepared ia a highly pure state by oxidizing potassium metal that is dissolved ia Hquid ammonia at —50° C. 

Thallic oxide can be prepared by reaction of thallium with oxygen or hydrogen peroxide and an alkaline thallium(I) solution. However, it is more easily made from the oxidation of thaHous nitrate by chlorine ia aqueous potassium hydroxide solution. It is insoluble in water but dissolves in carboxyUc acids to give carboxylates. 

The concentration dependence of iron corrosion in potassium chloride [7447-40-7] sodium chloride [7647-14-5] and lithium chloride [7447-44-8] solutions is shown in Figure 5 (21). In all three cases there is a maximum in corrosion rate. For NaCl this maximum is at approximately 0.5 Ai (about 3 wt %). Oxygen solubiUty decreases with increasing salt concentration, thus the lower corrosion rate at higher salt concentrations. The initial iacrease in the iron corrosion rate is related to the action of the chloride ion in concert with oxygen. The corrosion rate of iron reaches a maximum at ca 70°C. As for salt concentration, the increased rate of chemical reaction achieved with increased temperature is balanced by a decrease in oxygen solubiUty. 

Chemical Properties. Potassium cyanide is readily oxidized to potassium cyanate [590-28-3] by heating in the presence of oxygen or easily reduced oxides, such as those of lead or tin or manganese dioxide, and in aqueous solution by reaction with hypochlorites or hydrogen peroxide. 

Beryllium, calcium, boron, and aluminum act in a similar manner. Malonic acid is made from monochloroacetic acid by reaction with potassium cyanide followed by hydrolysis. The acid and the intermediate cyanoacetic acid are used for the synthesis of polymethine dyes, synthetic caffeine, and for the manufacture of diethyl malonate, which is used in the synthesis of barbiturates. Most metals dissolve in aqueous potassium cyanide solutions in the presence of oxygen to form complex cyanides (see Coordination compounds). 

The principal product of the reaction of the alkali metals with oxygen varies systematically down the group (Fig. 14.15). Ionic compounds formed from cations and anions of similar radius are commonly found to he more stable than those formed from ions with markedly different radii. Such is the case here. Lithium forms mainly the oxide, Li20. Sodium, which has a larger cation, forms predominantly the very pale yellow sodium peroxide, Na202. Potassium, with an even bigger cation, forms mainly the superoxide, K02, which contains the superoxide ion, O,. ... 

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