Oxides of Tin

This oxide is prepared by adding an alkaline carbonate to a solution of protochloride of tin, when a bulky white precipitate is formed of hydrated protoxide of tin. This is washed with warm water and dried at a heat not above 196 . The dry hydrate is now heated to redness in a current of carbonic acid gas, and the anhydrous protoxide is left. 

When moist hydrated peroxide of iron is mixed with a neutral solution of protochloride of tin, an exchange takes place, and a bulky precipitate of a grey colour is formed, which is a hydrate of sesquioxide of tin. Fe Oj -p 2 SnCl = Sn, 0,-1-2 FeCl. The sesquioxide is soluble in acids and in ammonia, the latter character distinguishing it from the protoxide. Its solution in hydrochloric add forms, with chloride of gold, the purple of Cassius and seems, indeed, better adapted for making it than the protoxide. 

This oxide exists in two distinct modifications. 1. If made by the action of nitric acid on tin, which is very violent, it appears as a dense white opaque powder, which is a hydrate, insoluble in water or acids. 2. If prepared by adding potash to perchloride of tin, it forms a very bulky hydrate, readily soluble in acids and also in alkalies. It seems rather to possess the characters of a weak acid than of a base. It is recognised in its solution in acids, by forming with alkalies, a bulky white hydrate, readily dissolved by excess of potash or soda, and by yielding, with sulphuretted hydrogen, a dirty yellow precipitate of bisul-phuret of tin. When melted with glass, peroxide of tin renders it opaque, forming a white enamel. 

The protoiqdide of tin is a brownish-red fusible solid, dissolving in water the periodide forms silky yellow crystals. 

This compound is formed by pouring melted tin on its own weight of sulphur, and stirring well. The mass is then powdered, mixed with more sulphur, and thrown by degrees into a red-hot crucible, by which means the whole of the tin is sulphurised. It forms a bluish black brittle solid, having metallic lustre. It is also formed when sulphuretted hydrogen acts on solutions of protoxide or protochloride of tin. 

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Fig. 5.2 The n-Cd(Se,Te)/aqueous Cs2Sx/SnS solar cell. P, S, and L indicate the direction of electron flow through the photoelectrode, tin electrode, and external load, respectively (a) in an illuminated cell and (b) in the dark. For electrolytes, m represents molal. Electron transfer is driven both through an external load and also into electrochemical storage by reduction of SnS to metaUic tin. In the dark, the potential drop below that of tin sulfide reduction induces spontaneous oxidation of tin and electron flow through the external load. Independent of illumination conditions, electrons are driven through the load in the same direction, ensuring continuous power output. (Reproduced with permission from Macmillan Publishers Ltd [Nature] [60], Copyright 2009)...

The formation of tin(III) intermediate during the oxidation of tin(II) has been postulated earlier in some cases, although direct evidence has not been quoted. Recently a couple of cobalt(III) complexes were supposed by Higginson et u/." to demonstrate the presence of tin(III). 

The method proposed is appropriate to show the presence of a strongly reducing intermediate. However, it is usually not possible to identify this entity as tin(III) merely on the evidence of the consumption of cobalt(III) complex present. To this end additional (kinetic) evidence is necessary. Nevertheless, the investigation of the induced reduction of cobalt(III) complexes is useful as a simple means of deciding whether the oxidation of tin(II) involves 1- or 2-equivalent steps. 

During oxidation of tin(II) ions by hydrogen peroxide, iodine, bromine, mercury(ir) and thallium(III) the induced reduction of cobalt(in) complexes cannot be observed. Therefore, it was concluded that these reactions proceed by 2-equivalent changes in the oxidation states of the reactants. 

FIGURE 40 Patina. Patina is a colored (usually green) layer of corrosion products that frequently develops naturally on the surface of copper and copper alloys exposed to the environment. Since it is sometimes appreciated aesthetically and as a proof of age, patina is also developed artificially, by chemical means, as a simulated product of aging. Copper patina generally includes such compounds as copper oxides, carbonates, and chlorides. In bronze and brass patinas, these compounds are mixed with the oxides of tin and lead resulting from the corrosion of the other components of the alloys. In any particular patina there may be many layers, not necessarily in the order shown in the illustration. 

Addition of an aqueous solution of the fluoride to one of the nitrate unexpectedly gave no precipitate of magnesium fluoride, and the solution was allowed to evaporate, first at ambient temperature, and then in a warm place, giving a wet white solid. While being manipulated with a spatula, this exploded with some violence, brown fumes were evolved and the solid was transformed into a dry tan-coloured powder. It was thought that oxidation of tin(II) to (IV) had occurred, the nitrate being reduced to nitrogen oxide. 

The very active unstable tin(III) ion is supposed to play an important role in this chain mechanism of tin(II) oxidation. Cyclohexane, introduced in the system Sn(II) + dioxygen, is oxidized to cyclohexanol as the result of the coupled oxidation of tin and RH. Hydroxyl radicals, which are very strong hydrogen atom acceptors, attack cyclohexane (RH) with the formation of cyclohexyl radicals that participate in the following transformations ... 

Biodiesel is a mixture of methyl esters of fatty acids and is produced from vegetable oils by transesterification with methanol (Fig. 10.1). For every three moles of methyl esters one mole of glycerol is produced as a by-product, which is roughly 10 wt.% of the total product. Transesterification is usually catalyzed with base catalysts but there are also processes with acid catalysts. The base catalysts are the hydroxides and alkoxides of alkaline and alkaline earth metals. The acid catalysts are hydrochloride, sulfuric or sulfonic acid. Some metal-based catalysts can also be exploited, such as titanium alcoholates or oxides of tin, magnesium and zinc. All these catalyst acts as homogeneous catalysts and need to be removed from the product [16, 17]. The advantages of biodiesel as fuel are transportability, heat content (80% of diesel fuel), ready availability and renewability. The... 

In the first sweep, only the current for the oxidation of tin was observed. As tin was removed gradually by the repetition of sweeps, an oxidation peak grew. Although the potential of the oxidation peak was the same with the that of pure platinum, the starting potential was more cathodic, which resulted in the widening of the peak. After the 8 th cycle, this early oxidation current decreased and the shape of the peak became like pure platinum. 

For both the smooth and high area electrodes, the methanol oxidation current was small at first and most of the current was made up of the oxidation of tin. Then the methanol oxidation current increased. The high area Pt-Sn electrode maintained the constant oxidation cxirrent afrer that. In contrast, the smooth Pt-Sn electrode showed a decay although the final current (after 2 min.) was slightly larger than that of pure platimun. Somehow tin seems more easily desorbed from the surface of smooth platinum than of hi area platimun. 

The hydrous oxide of tin adsorbs undissociated alizarinic acid to give an orange lake. The yellow is due to undissociated alizarinic acid with probably just enough alizarin ion to account for the orange color. 

The hydrous oxide of tin adsorbs undissociated sodium alizarate to. give a purple lake. There may be some alizarin ion present. 

Colored glazes are made with the addition of nearly pure oxides of manganese, copper, iron, chromium, cobalt, et cetera ) opaque glasses, ot enamels, by the addition of oxide of tin, or phosphate of lime for which see Porcelain True and Earthenware, Some of the ordinary lead glazes for soft porcelain are given below —... 

Transparent anil opaque colors or enamels are used with equal effect upon a white and almost opaque ground, suck as porcelain. Transparent colors are rendered opaque, by the addition of oxide of tin and oxide of aino is used for enlivening tbo different tints, a proporty peculiar to the oxide of that metal, and the effect of which is greatly enhanced by tho fact that it imparts no color to the glass it also Improves the sulphur-yellow colors of the oxide of antimony. 

Before the blowpipe on charcoal it melts in a strong heat, turns white. on the surface, and deposits a fixed sublimate of binoxide of tin round the assay. After roasting, it affords, with the usual fluxes, the peculiar reactions of iron and copper, and a brittle globnleof the latter metal on fluxing, with soda and borax. Nitric acid decomposes it, dissolving the iron and copper, and leaving a deposit of sulphur and of bin-oxide of tin. The following analyses indicate the composition of a few samples of this ore samples A and b from Hucl Bock . 0 from St. Michael s Mount, and d from Zinnwald —... 

Oxides.—Amongst the simple oxides may be classed —oxide of chromium, oxide of iron, oxide of uranium, oxide of manganese, oxide of zinc, oxide of cobalt, oxide of antimony, oxide of copper, oxide of tin. 

Oxide of Tin—SaOj—may be prepared by treating the metal with nitric acid. In its most concentrated form the ooid does not immediately aot, but will violently effervesce with heat upon the addition of a few drops of wator. The peroxide of tin remains in tho form of a white insoluble powder, and is purified by washing with boiling distilled water, and drying at a dull-red beat.. ... 

The glaze or enamel is composed of quartz-sand, soda, common salt, and a mixture of calcined tin and lead. The two metals are more easily oxidizad when mixed the oxide of tin produced—Sn 0,—acting the part of nn acid to the oxide of lead—PbO. The mixture is prepared by placing tho lead with about one-fourth of tin in a special fumuoe, where it is exposed ta heat and a curroiit of air. A yellowish ash of tin and lead is formed, which is carefully calcined to oxidize thoroughly all the metallic particles. This metallic ash is mixed -to form tho enamel in the following proportions —. 

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