Caesium halides

The differences between the mol. vol. of the sodium and the potassium salts are markedly greater than between the members of each group. It will also be observed that replacing chlorine by bromine increases the mol. vol. of the halide salts by approximately the same unit this is also the case when bromine is replaced by iodine, but the substitution of bromine by iodine produces a larger increase than the substitution of chlorine by iodine. The mol. vol. of caesium halides is much smaller than would have been anticipated by analogy with the other members of the series. It is doubtful if ammonium belongs to the potassium group in spite of the crystal symmetry. 

The reported specific gravity of ammonium iodide 3 ranges from H. G. F. Schroder s 2 443 to H. Schifi and U. Monsacchi s 2"5168 (15°). The best representative value may be taken as 2-511. The molecular volumes of the ammonium halides come between those of rubidium and caesium halides for example, ammonium chloride, 34-01 ammonium bromide, 39 62 ammonium iodide, 57 51. W. Biltz has also studied the mol. vol. of this salt. 

Copper(i).—Halides and Pseudohalides. The enthalpies of mixing CuCl and CuBr with the corresponding caesium halides have been measured at 810 and 663 °C (CuCl). There are analogies between these systems and the LiX-CsX systems, and the... 

It is a remarkable feature that the experimental data obtained in Na+-based halides had led Smirnov to the conclusion that the minimum complexation ability takes place in chloride melts [81], but it is not so for potassium- and caesium-based halides. Therefore, the stability of alkali metal cation-halide ion is dependent not only on the anion properties but also on those of the cation. In the potassium and caesium halides this reason shifts the minimum of the complexation ability to the bromide melts, which makes these media more acidic than the corresponding chlorides and iodides. 

By analysing the E-pO dependences in molten caesium halides at 800 °C, it is easily seen that these dependences are two-sectional with the inflection points located at pO 3. Even at high pO values (low oxide-ion... 

In contrast to the potassium and caesium halide melts, a monotonous change of the dissociation constant of carbonate ion in the sequence of sodium halides was observed. This distinction has been explained on p. 147 by the different stabilities of the inner complexes formed by melt ions in individual molten alkali metal halides, and by the different character of their changes with the change in the melt anion. The stability of the complex changes greatly in the potassium and caesium chloride-bromide-iodide sequences (the minimum is observed in the bromide melts), whereas in the sodium halides the chloride complexes possess the lowest stability and the iodide... 

Experiments under the restrictions of classical thermoelectrochemistry in open cells with moderate temperature variation addressed, to some extent, also the conditions in the bulk electrolyte solution and the properties of ions. Potentiometric measurements in aqueous solutions of hydrogen and potassium bromides yielded the temperature dependence of activity coefficients of important ions [58]. As mentioned in Chap. 2, all electrolyte solutions tend to approach the ideal state with increasing temperature. The conductance of various electrolytes has been studied in dependence on temperature [59-66]. Solvents studied were propanol [59], propylene carbonate [60, 64], dimethoxyethane [65], primary alcohols and acetonitrile [62]. Conductance values were used to determine transference numbers of ions in non-aqueous solution [62]. Salt melts of sodium and caesium halides also have been studied [66]. Theoretical considerations were subject of [63]. 

Ammonium Dioxalato - diammino - chromium, [Cr(NH3)2 (C204)2]NH4.2H20, is obtained in red needles by acting upon dibromo-diaquo-diammino-chromic bromide with aqueous oxalic acid at a temperature of 60° C. The colour changes in solution to dark red and the salt separates. From the ammonium salt other salts may be prepared by treating an aqueous solution with metallic halide. The potassium salt crystallises in red needles containing two molecules of water the sodium salt crystallises in dark red prisms the lithium salt in red needles or leaflets and the caesium salt in dark red needles. These salts are very stable and may be reerystallised from water. 

The Group 1 halides have the NaCl structure (6 6 coordination) except for the chloride, bromide and iodide of caesium, which have the CsCl structure (8 8 coordination). The plots shown in Figure 3.3 show a general decrease in the negative value of as the cation radius... 

The electrical conductivities of soln. of a great many compounds in liquid hydrogen halides have been measured by E. H. Archibald and D. McIntosh. The conductivity is raised considerably by phosphoryl chloride. Sodium sodium sulphide, borate, phosphate, nitrate, thiosulphate, and arsenate chromic anhydride potassium nitrate, hydroxide, chromate, sulphide, bisulphate, and ferro- and ferri- cyanide ammonium fluoride and carbonate j rubidium and caesium chloride magnesium sulphate calcium fluoride ... 

Different metal chlorides unite with one another to form double lasts. Just as the acidic and basic oxides unite together to form oxy-salts, so do the halides of an electropositive element (or radicle) unite with a halide of a less positive element (heavy metal or metalloid) to form double halides. So far as is known the alkali chlorides do not unite with one another to form double salts, nor do the halides of the same natural group form compounds with one another, but compounds of the alkali chlorides with the chlorides of the more electronegative chlorides are known. A comparison of nearly 500 double halides has been made by H. L. Wells (1901).1 He calls the one component—e.g. the alkali halide—the positive halide, and the other the negative halide. A. Werner calls the halide which plays the role of the basic oxide, the basic halide, and the other, the acid halide. A great many of the simple types of the double salts predominate. Writing the number of molecules of the positive halide first, and the negative halide second, salts of the 2 1 and 1 1 ratios cover about 70 per cent, of the list of known double halides, and 4 1, 3 1, 3 2, 2 3, and 1 2 represent over 25 per cent. Two halides sometimes unite in several proportions—for instance, six caesium mercuric halides have been reported where... 

CsCl HgCl2=3 1, 2 1, 1 1, 2 3, 1 2, and 1 5 and five caesium antimonious fluorides where CsF SbF3=l 1, 3 4, 4 7, 1 2, and 1 3. According to I. Remsen s rale (1889) When a halide of any element combines with a halide of an alkali metal to form a double salt, the number of molecules of the alkali salt which are added to one molecule of the other halide is never greater, and is generally less than the number of halogen atoms contained in the latter—for instance, in the double fluoride of sodium and aluminium, where the negative halide has three fluorine atoms, no more than three molecules of sodium fluoride will be found united with one of aluminium fluoride. 

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