Oxygen oxidisability

The four-electron change necessary for the quantitative conversion to nitrogen occurs only within certain limits of pH, concentration and temperature. Chlorine, bromine, iodine and iodates bring about this reaction quantitatively at pH 7. Dissolved molecular oxygen oxidises aqueous hydrazine to nitrogen in a series of stages, so hydrazine is an effective deoxidant for boiler-water. Several metal ions, particularly copper, catalyse the reaction. 

Finally oxygen oxidises the iron(ll) hydroxide to iron(lll) oxide (rust) ... 

What happens is that hydrogen peroxide, produced by the fungus s hyphae (from the partial reduction of oxygen) oxidises the ligninase heme to generate the 0=Fe(IV) porphyrin cation radical. This then extracts an... 

The electrode is very robust and can be used to determine the pH of solutions in the pH range 4-12 with an accuracy of 0.2 pH unit it does not contaminate the liquid under test, and since it has a low resistance, it can be used with a simple potentiometer. The electrode cannot, however, be used in the presence of dissolved oxygen, oxidising agents, hydrogen sulphide and heavy metal ions, or in highly acid or alkaline solutions. The E/pH conversion curve depends on the nature and concentration of the substances in the solution under test. The electrode is very susceptible to change of temperature. 

If this reaction is carried out at 273 K some unstable lead(IV) chloride is initially formed (p. 200). Other oxidising reactions of lead(lV) oxide include the evolution of oxygen when heated with concentrated sulphuric acid ... 

All carbon compounds, if oxidised by either oxygen or an oxide (such... 

In the presence of catalyst, usually platinum, ammonia is oxidised by oxygen (and air) to nitrogen oxide. NO. This reaction, used to obtain nitric acid from ammonia (p. 238), can be demonstrated in the laboratory using the apparatus shown in Figure 9.4 the oxygen rate should be slow. 

Phosphorus(III) oxide reacts slowly with oxygen at ordinary temperatures to give the pentoxide, P40,g. The reaction is rapid if the oxide is heated in air. It is oxidised vigorously by chlorine and bromine which form the oxidehalides, POX3. 

Antimony(V) oxide can be prepared by treating antimony with concentrated nitric acid. It is an oxidising agent and when gently heated loses oxygen to form the trioxide. (The change in oxidation state stability shown by antimony should be noted since it corresponds to increasing metallic character.)... 

Ozone is very much more reactive than oxygen and is a powerful oxidising agent especially in acid solution (the redox potential varies with conditions but can be as high as + 2.0 V). Some examples are 1. the conversion of black lead(ll) sulphide to white lead(II) sulphate (an example of oxidation by addition of oxygen) ... 

Oxygen is unaffected by aqueous acids unless they have powerful reducing properties when the acid is oxidised. For example... 

Evidence for the solvated electron e (aq) can be obtained reaction of sodium vapour with ice in the complete absence of air at 273 K gives a blue colour (cf. the reaction of sodium with liquid ammonia, p. 126). Magnesium, zinc and iron react with steam at elevated temperatures to yield hydrogen, and a few metals, in the presence of air, form a surface layer of oxide or hydroxide, for example iron, lead and aluminium. These reactions are more fully considered under the respective metals. Water is not easily oxidised but fluorine and chlorine are both capable of liberating oxygen ... 

Hydrogen peroxide has both oxidising properties (when it is converted to water) and reducing properties (when it is converted to oxygen) the half-reactions are (acid solution) ... 

It is a gas at room temperature with a boiling point of 128 K. It is a strong oxidising agent, some reactions occurring with explosive violence. Water hydrolyses it slowly at room temperature, but the reaction evolving oxygen is rapid in the presence of a base, and explosive with steam ... 

Unexpectedly we find that the bromate(V) ion in acid solution (i.e. effectively bromic(V) acid) is a more powerful oxidising agent than the chlorate(V) ion, CIO3. The halates(V) are thermally unstable and can evolve oxygen as one of the decomposition products. Potassium chlorate(V), when heated, first melts, then resolidifies due to the formation of potassium chlorate(VII) (perchlorate) ... 

Hydrated cobalt III) sulphate, Co2(S04)3. JSHjO is obtained when cobalt(II) sulphate is oxidised electrolytically in moderately concentrated sulphuric acid solution it is stable when dry but liberates oxygen from water. Some alums, for example KCo(S04)2.12H,0 can be obtained by crystallisation from sulphuric acid solutions. In these and the sulphate, the cation [CofHjO) ] may exist it is both acidic and strongly oxidising. 

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