Lithium vapor pressure

For p(Ar) >0.7 mbar (0.5 torr) the argon begins to diffuse into the central part, if the temperature and thus the lithium vapor pressure remains constant while / (Ar) increases. The slope of the curve Aco(p) yields for p > 0.7 mbar the cross section for LiJ + Ar collisions. For the example depicted in Fig. 8.5 the cross sections for line broadening are (LiJ + Li) = 60 nm and (Li + Ar) =41 nm, whereas the line shifts are dvjdp — —26 MHz/mbar for Li + Ar collisions [981]. Similar measurements have been performed on Sr Rydberg atoms [982], where the pressure shift and broadenings of Rydberg levels R n) for the principle quantum numbers n in the range S [Pg.435]

Anionic polymerization of vinyl monomers can be effected with a variety of organometaUic compounds alkyllithium compounds are the most useful class (1,33—35). A variety of simple alkyllithium compounds are available commercially. Most simple alkyllithium compounds are soluble in hydrocarbon solvents such as hexane and cyclohexane and they can be prepared by reaction of the corresponding alkyl chlorides with lithium metal. Methyllithium [917-54-4] and phenyllithium [591-51-5] are available in diethyl ether and cyclohexane—ether solutions, respectively, because they are not soluble in hydrocarbon solvents vinyllithium [917-57-7] and allyllithium [3052-45-7] are also insoluble in hydrocarbon solutions and can only be prepared in ether solutions (38,39). Hydrocarbon-soluble alkyllithium initiators are used directiy to initiate polymerization of styrene and diene monomers quantitatively one unique aspect of hthium-based initiators in hydrocarbon solution is that elastomeric polydienes with high 1,4-microstmcture are obtained (1,24,33—37). Certain alkyllithium compounds can be purified by recrystallization (ethyllithium), sublimation (ethyllithium, /-butyUithium [594-19-4] isopropyllithium [2417-93-8] or distillation (j -butyUithium) (40,41). Unfortunately, / -butyUithium is noncrystaUine and too high boiling to be purified by distiUation (38). Since methyllithium and phenyllithium are crystalline soUds which are insoluble in hydrocarbon solution, they can be precipitated into these solutions and then redissolved in appropriate polar solvents (42,43). OrganometaUic compounds of other alkaU metals are insoluble in hydrocarbon solution and possess negligible vapor pressures as expected for salt-like compounds. 

More extensive vapor pressure data for lithium and other metals are given ia Ref. 43. To convert kPa to mm Hg, multiply by 7.5. 

Lithium carbonate addition to HaH-Heroult aluminum ceU electrolyte lowers the melting point of the eutectic electrolyte. The lower operating temperatures decrease the solubiHty of elemental metals in the melt, allowing higher current efficiencies and lower energy consumption (55). The presence of Hthium also decreases the vapor pressure of fluoride salts. 

The high solubility of the salt and resultant low water vapor pressure (58) of its aqueous solutions ate usehil ia absorption air conditioning (qv) systems. Lithium bromide absorption air conditioning technology efficiencies can surpass that of reciprocal technology usiag fluorochlorocarbon refrigerants. 

Lithium Iodide. Lithium iodide [10377-51 -2/, Lil, is the most difficult lithium halide to prepare and has few appHcations. Aqueous solutions of the salt can be prepared by carehil neutralization of hydroiodic acid with lithium carbonate or lithium hydroxide. Concentration of the aqueous solution leads successively to the trihydrate [7790-22-9] dihydrate [17023-25-5] and monohydrate [17023-24 ] which melt congmendy at 75, 79, and 130°C, respectively. The anhydrous salt can be obtained by carehil removal of water under vacuum, but because of the strong tendency to oxidize and eliminate iodine which occurs on heating the salt ia air, it is often prepared from reactions of lithium metal or lithium hydride with iodine ia organic solvents. The salt is extremely soluble ia water (62.6 wt % at 25°C) (59) and the solutions have extremely low vapor pressures (60). Lithium iodide is used as an electrolyte ia selected lithium battery appHcations, where it is formed in situ from reaction of lithium metal with iodine. It can also be a component of low melting molten salts and as a catalyst ia aldol condensations. 

The reaction involves two electrons per thionyl chloride [7719-09-7] molecule (40). Also, one of the products, SO2, is a Hquid under the internal pressure of the cell, facihtating a more complete use of the reactant. Finally, no cosolvent is required for the solution, because thionyl chloride is a Hquid having only a modest vapor pressure at room temperature. The electrolyte salt most commonly used is lithium aluminum chloride [14024-11-4] LiAlCl. Initially, the sulfur product is also soluble in the electrolyte, but as the composition changes to a higher SO2 concentration and sulfur [7704-34-9] huA.ds up, a saturation point is reached and the sulfur precipitates. 

Liquid Sorption. If a moist gas is passed through sprays of a liquid sorbent, such as lithium chloride or an ethylene glycol solution, moisture is removed from the air at a rate depending on the vapor pressure difference. This is a function of the absorbent concentration and is maintained at the required level by a regeneration cycle. The regeneration process is continuous and is achieved by allowing a percentage of the chemical into the exhaust-heated air. 

A piece of lithium metal was added to a flask of water on a day when the atmospheric pressure was 757.5 Torr. The lithium reacted completely with the water to produce 250,0 ml. of hydrogen gas, collected over the water at 23°C, at which temperature the vapor pressure of water is 21.07 Torr. (a) What is the partial pressure of hydrogen in the collection flask ... 

The following n/m values were obtained for the degrees of association n at molal concentration m, measured in ammonia by cryoscopy. Lithium phenolate (255a, 2.21 0.20/0.1530) is nearly dimeric in ammonia, while in pyridine and dioxolane it is tetrameric, as shown by vapor pressure and NMR measurements. The 2,6-dimethyl homologue (255b)... 

Lithium bromide is used in absorption, refrigeration and air-conditioning systems. A highly concentrated solution of the salt is an efficient absorbent of water vapor. The vapor pressure of such solution is very low. Other applications include the use of the salt as a swelling agent for wool, hair and other organic fibers as a catalyst in dehydrohalogenation reactions and as a sedative and hypnotic in medicine. 

This is an extremely complicated system for such a study, inasmuch as it is a three-component system consisting of an ionophore (lithium bromide) and an ionogen (bromosuccinic acid) in a smenogenic solvent (acetone). Further, the solvent has a high affinity for water and a comparatively high vapor pressure at 25°C. 

Limitations of saturaled sail sensors include (11 relatively slow response lime and (2) a lower limit to the mcasurcmenl range imposed by ihe nature of lithium chloride. The sensor cannot be used to measure dew points when the vapor pressure of waier is below- the saturation vapor pressure of lithium chloride, which occurs at about I 1% RH. In certain gases, ambient temperatures can he reduced, increasing the RH to above I 1% but the extra effort needed to cool the gas usually warrants selection of a different type of sensor. Fortunately, a large number of scienlilie and induslrial measurements fall above this limitation and are readily handled by the sensor. 

Colloidal potassium has recently been proved as a more active reducer than the same metal that has been conventionally powdered by means of shaking it in hot octane (Luche et al. 1984 Chou You 1987 Wang et al. 1994). In order to prepare colloidal potassium, a piece of this metal in dry toluene or xylene under an argon atmosphere is submitted to ultrasonic irradiation at ca. 10°C. A silvery blue color is rapidly developed, and in a few minutes the metal disappears. A common cleaning bath (e.g., Sonoclean, 35 kHz) filled with water and crushed ice can be used. A very fine suspension of potassium is thus obtained that settles very slowly on standing. In THF, the same method did not work. Attempts to disperse lithium in THF or toluene or xylene were unsuccessful, whereas sodium was dispersed in xylene but not in THF or toluene (Luche et al. 1984). Ultrasonic waves interact with the metal via their cavitational effects (see Section 5.2.4). These effects are closely related to the physical constants of the medium, such as vapor pressure, viscosity, and sur-... 

Vanadium oxytrichloride is a lemon-yellow liquid. Its boiling point is 124.5°C. at 736 mm. and 127.16°C. at 760 mm. It remains liquid at —77°. The vapor pressure at —77° is 4.1 mm. at 0°, 21 mm. and at 85°C., 270 mm. Its density in grams per milliliter is 1.854 at 0° and 1.811 at 32°C. At ordinary temperatures, it neither dissolves nor reacts with carbon, hydrogen, nitrogen, oxygen, silicon, tellurium, or metals except the alkali metals and antimony. The reactions with the alkali metals are explosive at characteristic temperatures, varying from 30°C. for cesium to 180°C. for sodium (lithium not determined). Small... 

A 0.205-g sample of contaminated LiH yielded 561 mL of gas measured over water at 22°C and a total pressure of 731 torr. Calculate the percent by weight of lithium metal in the sample. The vapor pressure of water at 22°C is 20 torr. 

Methyl Trimethylsilyl Tellurium1,5 2.3 g (15 mmol) of crude lithium methanetellurolate, prepared from methyl lithium and tellurium in tetrahydrofuran, are combined with 1.7 g (15.7 mmol) of chlorotrimethylsi-lane at 25°. The reaction is vigorous and exothermic. After 1 h, all volatile material is pumped from the reactor in through traps at — 45° and - 196°. The material in the - 45° trap is distilled through a series of traps at — 23°, — 45 , and — 196°. The pure product condenses in the — 45° trap yield 2.0 g (64%) vapor pressure 3 torr at 25". 

One serious constraint involved with the use of lithium as a plasma-facing material is its relatively high vapor pressure [21]. This restricted maximum permissible operating temperature coupled to its transition to a solid state below 181°C, means that lithium has a narrow temperature window in operational space. As will be discussed in the next section, enhanced erosion at elevated temperature will further restrict the size of this window. 

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