Silver carbonate, decomposition, crystal

A mixture of 150 parts of oxalic acid, 40 of potassium chlorate, and 20 of water is heated to 60°, and the soln. cone, in vacuo at 50° until it begins to crystallize. The cold liquid i3 then treated with 3 volumes of absolute alcohol, when potassium carbonate is precipitated. Fine deliquescent needles of potassium chlorite can be obtained by fractional crystallization in vacuo. The residue gives a further crop of crystals of the chlorite by treatment with 95 per cent, alcohol. Small yellow crystals of silver or lead chlorites can be obtained by double decomposition. 

This production of a peculiar degree of instability in the silver bromide, close to the atoms of sulphur in the sulphide, seems closely analogous to the other cases of promoter action, and the effects of a one-dimensional interface in a solid surface, which were considered in 3. It may be an effect of the same nature as the increased ease of decomposition of the calcium carbonate group, when this has calcium oxide groups adjacent to it. There is some evidence that the silver sulphide crystal lattice is rather more easily disorientated than the silver bromide, but since silver sulphide is, alone, not particularly sensitive to light, it seems certain that the sensitizing action of the sulphide speck must be due to a boundary action between the sulphide and the bromide.8... 

Many kinetic studies of the thermal decomposition of silver oxalate have been reported. Some ar-time data have been satisfactorily described by the cube law during the acceleratory period ascribed to the three-dimensional growth of nuclei. Other results were fitted by the exponential law which was taken as evidence of a chain-branching reaction. Results of both types are mentioned in a report [64] which attempted to resolve some of the differences through consideration of the ionic and photoconductivities of silver oxalate. Conductivity measurements ruled out the growth of discrete silver nuclei by a cationic transport mechanism and this was accepted as evidence that the interface reaction is the more probable. A mobile exciton in the crystal is trapped at an anion vacancy (see barium azide. Chapter 11) and if this is further excited by light absorption before decay, then decomposition yields two molecules of carbon dioxide ... 

Chloral hydrate—Chloral (U. S.)—is a white, crystalline solid fuses at 57° fl84°.6 F.) boils at 98° (203°.4 F.), at which temperature it suffers partial decomposition into chloral and H.O volatilizes slowly at ordinary temperatures is very soluble in HjO neutral in reaction has an ethereal odor, and a sharp, pungent taste. Concentrated HjSO. decomposes it with formation of chloral and chloralid. H NO. converts it into trichloracetic acid. When pure it gives no precipitate with silver nitrate solution, and is not browned by contact with concentrated H,SO.. Under-the influence of sunlight it is violently decomposed by potassium chlorate. Chlorin, phosgene gas, carbon dioxid, and chloroform are given off, and after a time, crystals of potassium trichlor-acetate separate from the cooled mixture. 

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