Alkali metal alloy, liquid

The lack of homopolyatomic anions for elements to the left of group IV In Table I is noteworthy. Zlntl reported no success with reactions of alkali metal alloys of the copper and zinc family elements and of thallium with liquid ammonia, and the generally stabilizing effect of crypt has not been evident In our own Investigations of alloys of mercury and thallium. On the other hand. It is possible to Isolate a white crypt-potassium gold compound from ammonia solutions at low temperatures which decomposes to elemental gold (+ ) above about -10°C (30). 

Fig. 355. Extraction of alkali metal alloys with liquid ammonia.

Rubidium can be liquid at room temperature. It is a soft, silvery-white metallic element of the alkali group and is the second most electropositive and alkaline element. It ignites spontaneously in air and reacts violently in water, setting fire to the liberated hydrogen. As with other alkali metals, it forms amalgams with mercury and it alloys with gold, cesium, sodium, and potassium. It colors a flame yellowish violet. Rubidium metal can be prepared by reducing rubidium chloride with calcium, and by a number of other methods. It must be kept under a dry mineral oil or in a vacuum or inert atmosphere. 

It is now well established that in lithium batteries (including lithium-ion batteries) containing either liquid or polymer electrolytes, the anode is always covered by a passivating layer called the SEI. However, the chemical and electrochemical formation reactions and properties of this layer are as yet not well understood. In this section we discuss the electrode surface and SEI characterizations, film formation reactions (chemical and electrochemical), and other phenomena taking place at the lithium or lithium-alloy anode, and at the Li. C6 anode/electrolyte interface in both liquid and polymer-electrolyte batteries. We focus on the lithium anode but the theoretical considerations are common to all alkali-metal anodes. We address also the initial electrochemical formation steps of the SEI, the role of the solvated-electron rate constant in the selection of SEI-building materials (precursors), and the correlation between SEI properties and battery quality and performance. 

Pure mercury does not easily wet steels and certain other structural alloys, thus it is an unwetted case. It causes the direct transition from liquid phase to film boiling heat transfer. The phenomenon has also, on occasion, been observed with alkali metals (Noyes and Lurie, 1966 Avksentyuk and Mamontova, 1973). Figure 2.42 shows experimental heat transfer results for pool boiling of pure mercury on... 

Bonilla, C. F., D. L. Sawhuey, and N. M. Makansi, 1962, Vapor Pressure of Alkali Metals III, Rubidium, Cesium, and Sodium-Potassium alloy up to 100 psia, Proc. 1962 High Temperature Liquid MetaI Heat Transfer Tech. Meeting, BNL-756, Brookhaven, NY. (3)... 

Polyatomic anions of tin can be prepared in solution, using alloys of tin with alkali metals which are remarkably soluble in liquid ammonia. The obtained colored solutions contain the cluster anion [Sng]4, 68a106. Upon treatment with a crown ether in ethylenediamine, crystalline compounds [Na(crypt)+]4[Sn9]4 could be prepared where crypt = N(CH2CH20CH2CH20CH2CH2)3N ... 

This cluster is prepared from the reaction of an alloy of Pb with an alkali metal, dissolved in liquid ammonia with the crown ether, crypt, dissolved in ethylenediamine. 

A comparison between the behaviour in the liquid and in the solid state is schematically presented in Fig. 3.3 for a number of alloys of the alkali metals with... 

In liquid alloys of alkali metals with lead there are peaks in the plot of the resistivity p against composition—in KPb p rises to 1000 jiD cm... 

A few of the relations of the alkali metals with one another have been investigated. Potassium with about 30 per cent, of sodium forms an alloy which is liquid at ordinary temp., and which has the appearance of mercury. This becomes pasty at 8°, and solidifies at a lower temp. If the alloy contains 77 per " /o" S>"x cent, of potassium, it remains liquid even... 

In a similar manner the so-called Zintl salts composed of alkali metal cations and clusters of metals as anions (see Chapter 16) were known in liquid ammonia solution but proved to be impossible to isolate Upon removal of the solvent they reverted to alloys. Stabilization of the cations by complexation with macrocyclic ligands allowed the isolation and determination of the structures of these compounds. 

It has been known for nearly 100 years that posttransilion metals dissolve in liquid ammonia in the presence of alkali metals to give highly colored anions.lw In the 1930s. polyatomic anions (Fig. 16.66a.b) such as Sni -, Pbj-, PbJ", Sb , and Bi were identified but not structurally characterized. Attempts at isolating crystals were unsuccessful because they decomposed in solution. This problem was overcome in 1975 by stabilizing the cation of the salt as a cryptate (see Chapter 12). e.g., [Na(crypt)J,Pb, and lNa(crypt)]4Sn9, which reduces the tendency of the salt to convert lo a metal alloy.166... 

Potassium, a soft, low density, silver-colored metal, has high thermal and electrical conductivities, and very low ionization energy. One useful physical property of potassium is that it forms liquid alloys with other alkali metals such as Na, Rb, and Cs. These alloys have very low vapor pressures and melting points. 

The explosion of chloroform in contact with an alkali metal may be demonstrated by means of the apparatus illustrated in Figure 92. About 0.3 gram of sodium or of potassium or of the liquid alloy of the two is introduced into a thin-wall glass tube, or, better yet, is sealed up in a small glass bulb, 6 to 8 mm. in diameter, which has a capillaiy 15 to 20 mm. in length. The tube or bulb containing the alkali metal is placed in the bottom of a narrow test tube into which 1 or 2 cc. of chloroform has already been introduced, and the apparatus is then... 

When metallic barium is dissolved in liquid sodium or K/Na alloy in an inert atmosphere of nitrogen, an extensive class of mixed alkali metal-barium... 

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