Alkali metals melting points

TABLE 6.4 Properties of Alkali Metals Melting Boiling Point (°C) Point (°C) Density (g/cm3) First Ionization Energy (kj/mol) Abundance on Earth (%) Atomic Radius (pm) Ionic (M+) Radius (pm)... 

Table Properties of alkali metals melting and boiling points, atomisation and ionisation enthalpies, ionic and standard electrode potentials...

TABLE 2.1 ALKALI METALS BOILING POINTS AND MELTING POINTS ... 

The thennal evaporation source was the earliest used to produce metal clusters in the gas phase [H, 12 and 13], mostly for clusters of the alkalis and other low melting point materials. In this technique, a bulk sample is simply... 

Sulphonic acids. The aromatic sulphonic acids and their alkali metal salts are soluble in water, but insoluble in ether (Solubility Group II). They are best characterised by conversion into crystalline S-benzyl-iso-thiuronium salts (see Section IV,33,2 and 111,85,5), which possess characteristic melting points. A more time-consuming procedure is to treat the well-dried acid or... 

Tantalum is a gray, heavy, and very hard metal. When pure, it is ductile and can be drawn into fine wire, which is used as a filament for evaporating metals such as aluminum. Tantalum is almost completely immune to chemical attack at temperatures below ISOoC, and is attacked only by hydrofluoric acid, acidic solutions containing the fluoride ion, and free sulfur trioxide. Alkalis attack it only slowly. At high temperatures, tantalum becomes much more reactive. The element has a melting point exceeded only by tungsten and rhenium. Tantalum is used to make a variety... 

Metals do not generally react with vitreous siUca below 1000°C or their melting point, whichever is lower. Exceptions are alurninum, magnesium, and alkah metals. Aluminum readily reduces siUca at 700—800°C. Alkali metal vapors attack at temperatures as low as 200°C. Sodium vapor attack involves a diffusion of sodium into the glass, followed by a reduction of the siUca. 

Excess sodium hydroxide present can also be troublesome as the alkali reacts with the SO3 present in the gas stream to form a range of alkali sulfates which in themselves are highly corrosive to metallic components. In addition, the combination of alkali sulfate -l- V2O5 can result in compounds having melting points as low as 600°E. This situation is only encountered when alkali is present in amounts in excess of that which can react stoichiometrically with V2O5, since the formation of alkali vanadates is favored over that of alkali sulfates. 

Group IIA metals inelude Be, Mg, Ca, Sr, Ba and Ra whieh are grey, moderately-hard, high melting-point substanees. Like the alkali metals they attaek water to liberate hydrogen but with less vigour. The salts of the alkaline earths are generally less stable towards heat and water than those of alkali metals, and less water soluble. 

The chemical resistance of PTFE is almost universal It resists attack by aqua regia, hot fummg nitnc acid, hot caustic, chlorine, chlorosulfonic acid, and all solvents. Despite this broad chemical resistance, PTFE is attacked by molten alkali metals, ammonia solutions of such metals, chlorine trifluoride, and gaseous fluonne at elevated temperature and pressure PTFE swells or dissolves m certam highly fluonnated oils near its melting point. Specific lists of chemicals compatible with PTFE are available [/.8]... 

Figure 4.3 Melting point and boiling point of alkali metal halides.

All the alkalies are metals in their elementary states. When the metal surfaces are clean, they have a bright, silvery luster. The metals are excellent conductors of electricity and heat. They are soft and malleable, and have low melting points (compared with almost all other elementary metals). 

Zinc phthalocyanine (PcZn) is prepared from phthalonitrile in solvents with a boiling point higher than 200 C, e.g. quinoline277,278 or 1-bromonaphthalene,137 or without solvent in a melt of phthalonitrile.83,116 The zinc compound normally used is zinc(ll) acetate or zinc powder. The reaction of zinc(II) acetate with phthalic acid anhydride, urea and ammonium mo-lybdate(VI) is also successful.262 The metal insertion into a metal-free phthalocyanine is carried out in an alcohol (e.g.. butan-l-ol).127,141,290 This reaction can be catalyzed by an alkali metal alkoxide.112,129... 

The ionic conductivity of alkali-metal chloroaluminates was also investigated by Weppner and Huggins [37] but also only in the temperature range between room temperature and just above the melting point. At room temperature the ionic conductivity... 

B.20 List the names, symbols, and atomic numbers of the alkali metals. Characterize their reactions with water and describe their trend in melting points. 

The saline hydrides are white, high-melting-point solids with crystal structures that resemble those of the corresponding halides. The alkali metal hydrides, for instance, have the rock-salt structure (Fig. 5.39). 

FIGURE 14.12 The melting points of the alkali metals decrease down the group. The numerical values shown here are degrees Celsius. 

Salt-inclusion solids described herein were synthesized at high temperature (>500°C) in the presence of reactive alkali and alkaline-earth metal halide salt media. For single crystal growth, an extra amount of molten salt is used, typically 3 5 times by weight of oxides. The reaction mixtures were placed in a carbon-coated silica ampoule, which was then sealed under vacuum. The reaction temperature was typically set at 100-150 °C above the melting point of employed salt. As shown in the schematic drawing in Fig. 16.2, the corresponding metal oxides were first dissolved conceivably via decomposition because of cor-... 

Many electrochemical devices and plants (chemical power sources, electrolyzers, and others) contain electrolytes which are melts of various metal halides (particularly chlorides), also nitrates, carbonates, and certain other salts with melting points between 150 and 1500°C. The salt melts can be single- (neat) or multicomponent (i.e., consist of mixtures of several salts, for their lower melting points in the eutectic region). Melts are highly valuable as electrolytes, since processes can be realized in them at high temperatures that would be too slow at ordinary temperatures or which yield products that are unstable in aqueous solutions (e.g., electrolytic production of the alkali metals). 

Primary aromatic amides are crystalline solids with definite melting points. Upon boiling with 10-20 per cent, sodium or potassium hydroxide solution, they are hydrolysed with the evolution of ammonia (vapour turns red litmus paper blue and mercurous nitrate paper black) and the formation of the alkali metal salt of the acid ... 

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