Alkalis vapour pressure

In the case of atoms UPS is unlikely to produce information which is not available from other sources. In addition many materials have such low vapour pressures that their UPS spectra may be recorded only at high temperatures. The noble gases, mercury and, to some extent, the alkali metals are exceptions but we will consider here only the specttum of argon. 

Rowley, A. T. et al., Inorg. Chem. Acta, 1993, 211(1), 77 Preparation of metal oxides by fusing metal halides with lithium oxide in a sealed tube leads to explosions if halide hydrates are employed, particularly lanthanide trihalide hydrates. The preparation succeeds with anhydrous halides. This will be purely a question of vapour pressure above an exothermic reaction the question is whether the vapour is water, or metal halide, and the reaction oxide formation, or hydration of lithium oxide. Like other alkali metal oxides, hydration is extremely energetic. 

Table XX.-—Vapour Pressure of Solid Alkali Polyiodides (Iodine Unity).

Krause et a/.123-125 have recently reported a series of measurements of the spin-orbit relaxation of the alkali metals in their first excited states (2P). The technique, for example for atomic caesium with AE = 554 cm-1, consists of irradiating the metal vapour with light from a monochromator to excite only one of the 2P states. The vapour pressure of the metal is controlled at 10-6 torr to avoid imprisonment of the resonance radiation. The components of the fluorescence light are measured with a photomultiplier by isolating the 2P - 2S lines with interference filters. In the presence of added gases which cause the transitions... 

By measuring the intensity of the beam transmitted through the cell when it was hot, and therefore with alkali vapour present, and also when it was cold, when the vapour pressure was negligible, aT was deduced using... 

Van Wijk and Seeder s viscosity equation, 91 vapour, density of saturated, 324 specific heat of saturated, 336, 346-7, 359 vapour pressure 226 alignment chart, 271 of aliphatic esters, 286 of alkali halides, 237,243 of benzene, 267 boiling-point method for, 235 in capillary tubes, 367 of carbon, 246 centri fugal force, effect of, on 292 constant, 335, 341 over curved surface, 366 determination of, 227-47 dew-point method, 241 of dibasic acids, 243 dynamical method, 235 effusion method, 241. electrification, effect of on, 238, 375 of elements 257 of esters, 250 f., 286 of fusible metal, 230 in... 

Hot phosphoric acid has been successfully used to digest ion-based alloys when HCl would have volatilized specific trace constituents. Phosphoric acid can also digest a wide range of aluminium slags, iron ores, chromium and alkali metals. The temperature and pressure profiles for H,POj indicate that temperatures of 240°C can be attained with just 3 atm. Because of its low vapour pressure, relatively high temperatures can be reached without disrupting the digestion. 

It should be noted that the materials are synthesized under non-equilibrium conditions as the experiments are performed in a dynamic vacuum, and the local vapour pressure of the alkali metal is unknown. The rate and extent of reaction will depend on the nature of the alkali metal, the temperature of the film and the presence of residual ambient gas impurities, which are not controlled in these preliminary experiments. At present, the effect of these variables on the conductivities cannot be assessed. Synthesis in a closed system will be required to determine the relevant thermodynamic parameters. 

The carbonates of group Ila elements and carbonates of alkali metals (Na, K and Li) are very common raw materials for glass and ceramics. Whereas carbonates of divalent metals decompose spontaneously at elevated temperatures producing solid oxides, alkali carbonates are comparatively stable with the exception of Li2C03 they melt without decomposition and show considerable vapour pressure. 

The rate of alkali-metal sulphate deposition will decrease when the temperature of collecting target surface exceeds 1075 K as shown in Figure 2. The decrease in the deposition of alkali-metal sulphates is related to the concentration of the volatile alkali-metals in the flue gas and the saturation vapour pressure of sodium and potassium sulphates ( ). The initial deposit on cooled surfaces contains a small amount of chloride as shown in Figure 2. 

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