Aqueous solutions oxidations

Fig. 12.1 Oxidation states of the actinide elements most stable ions in aqueous solutions ++ oxidation states observed in aqueous solutions +, unstable ions observed only as transient species. In solids precipitated from alkaline solutions.

The salt in aqueous solution oxidizes to cyanate when treated with sodium... 

This is probably the most important radical species in aqueous solution. Oxidative reactions of the hydroxyl radical, ( OH), with inorganic and organic compounds have been well documented [8]. Compilations of bimolecular (second-order) rate constants have been published [3,8]. The OH- can undergo several types of reactions with species in aqueous solution, including addition, hydrogen abstraction, and electron transfer. 

The majority of titanium (III) compounds are rather easily oxidized and must be handled in an inert atmosphere. However, the titanium(III) urea derivative is relatively stable and can be kept in dry air for several weeks without suffering any apparent oxidation. In moist air or aqueous solution oxidation is much more rapid. Hexaureatita-nium(III) perchlorate has been prepared by the reduction of titanium (IV) compounds and subsequent reaction of the titanium (III) ion with urea in the presence of sodium perchlorate. The following procedure is a modification of this method. 

Anhydrides Some oxides can become acids or bases by adding the elements contained in water. These compounds are called anhydrides. Oxides of nonmetalUc elements, such as carbon, sulfur, or nitrogen, produce an acid in aqueous solution. Oxides of metallic elements usually form basic solutions. For example, carbon dioxide, an oxide of a nonmetal, forms a solution of carbonic acid, whereas, calcium oxide (CaO) forms a basic solution of calcium hydroxide. 

Light, especially ultraviolet irradiation from a low-pressure mercury lamp, activates the browning, with results similar to those obtained by thermal activation.It has also been found that ultraviolet irradiation of starch in aqueous solution oxidizes it to carbon dioxide in 98% yield, but does not produce any mono- and oligo-saccharides. 

Concentrated nitric acid has been used to obtain nickel(III) complexes like [Ni L(N03)2]CI04 starting from [NPL](C104)2 (L = cyclam, Megcyclam) in aqueous solutions. Oxidation of the parent nickel(II) with nitric acid complexes also afforded the nickel(IV) species [Ni L] ( 104)2 where L is the amine-imine-oxime ligand (415) or... 

Formula weight 804.24. Small, dark-green tablets, yellow in transmitted light. Soluble in water, giving a dark-green color very slightly soluble in alcohol. The aqueous solution oxidizes in air the crystalline compound also oxidizes but more slowly. 

The only oxidation state of importance In aqueous solution Is the +2 state. Compounds of the +4 plumbic Ion are well known but are Invariably unstable or Insoluble in aqueous solution. Due to the dominant stability of the +2 state In aqueous solution oxidation -reduction reactions are of minor Importance In lead separations and determinations. The notable exceptions are anodic oj ldatlon to the dioxide and reduction to the metal either cathodloally or by Internal electrodeposltlon. 111000 reactions have been used for the separation and determination of lead and are dlsoussed In detail In section IV-10 of this report. 

The chlorine in an aqueous solution oxidizes the arsenous acid in a quantitative reaction as it follows ... 

Both tin and lead form divalent and tetravalent cations in aqueous solution. Oxide phases are known for all four metal ions, including blue-black tetragonal SnO(s), cassiterite (Sn02(s)), massicot (yellow PbO(s)), litharge (red PbO(s)) and plattner-ite (Pb02(s)). In alkaline solutions, the tin(IV) and lead(IV) ions react with hydroxide to produce the stannate (SnOj " or Sn(OH)g ) and plumbate (PbOj " or Pb(OH)5 ) ions. 

While incineration is the preferred method of disposal for wastes containing high concentrations of organics, it becomes expensive for aqueous wastes with low concentrations of organics because auxiliary fuel is required, making the treatment expensive. Weak aqueous solutions of organics are better treated by wet oxidation (see Sec. 11.5). 

The -t-4 stale is stabilized in aqueous solution by fluoride ions. Cm02 and Cmp4 are formed by strong oxidation or the action of fluorine. 

FenCon s reagent An aqueous solution of FeSO4 0rotherFe saltandhydrogen peroxide used for oxidizing polyhydric alcohols. 

Colourless crystals m.p. I25°C, soluble in water and alcohol. In aqueous solution forms equilibrium with its lactones. Gluconic acid is made by the oxidation of glucose by halogens, by electrolysis, by various moulds or by bacteria of the Acetobacter groups. 

Sodium sulphide, NajS, formed by reduction Na2S04 with CO or H2- Aqueous solutions are oxidized to sodium thiosulphate. 

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