Gallium dissolved

The presence of low-valent gallium, probably Ga1, species in aqueous solution has been proposed frequently. For example, some delayed reducing ability of gallium dissolved in HC1 has been observed, and gallium is one of the few reductants for perchloric acid, which may be due to the reactions... 

The electrochemical (or current) efficiency, EF, defined as moles of metal dissolved per Faraday, can be readily determined by recording the current, total time of electrolysis, and weight of gallium dissolved. For a more accurate determination, a silver voltammeter can be connected in series with the cell. Current efficiencies measured in this way are close to the theoretical value of 0.5 for the fundamental process Ga -> Ga2+ + 2e". The method given here for preparing gallium(11) compounds uses an electrolyte based on acetonitrile and is a marked improvement on earlier chemical or electrolytic routes to low-valent gallium compounds,1 from which mixed products, partially oxidized to the Ga(lll) state, were often obtained. 

The salt [Bu4N] [GaCl4] is precipitated from this electrochemically prepared solution by the addition of 2.8 g (0.5 mmole) of 50% aqueous solution of [Bu4N]C1. The precipitated solid (1.5 g) is subsequently dissolved in 10 mL of chloroform, from which a colorless crystalline product is obtained by the addition of 30 mL of diethyl ether (yield 1.40 g, ca. 72% based on gallium dissolved). 

In the case of the bromide, 1.61 g (0.5 mmole) of [Bu4N]Brin 5 mL of water is added. The copious precipitate is rinsed with water, collected, and air-dried, giving a crude yield of 2.50 g. Purification can be achieved by dissolving the solid in warm chloroform (20 mL), cooling, and adding diethyl ether (30 mL) to obtain 2.35 g of cream solid as small crystals (yield ca. 86%, based on gallium dissolved). 

Fig. 14. Solution formation by the triva-lent rare earth metals. Extensive solid solutions means that 5 at.% or more of R in M or M in R is found in most of the R-M (or R-R ) systems when M (or R ) is shaded, where R is a second rare earth element in an intra rare earth binary alloy system. For M = Ga there is some evidenee that gallium dissolves extensively in the high-temperature bee form of the rare earth metals.

Reduced halogens. Gallium dissolves slowly in either 1-M or 12-M HCl, producing [Ga2Cl6] ", i.c., [(-GaCl3)2], and H2. Rather similar are HBr and HI. The fresh [Ga2X6] " ions are quite strong rcductants. 

The hydrated nitrate, Ga(N02(3 9H20, is formed by dissolving gallium ia nitric acid. 

Hydrolysis. 1,1,1-Trichloroethane heated with water at 75—160°C under pressure and in the presence of sulfuric acid or a metal chloride catalyst decomposes to acetyl chloride, acetic acid, or acetic anhydride (54). However, hydrolysis under normal use conditions proceeds slowly. The hydrolysis is 100—1000 times faster with trichloroethane dissolved in the water phase than vice versa. Refluxing 1,1,1-trichloroethane with ferric and gallium chloride... 

The equilibrium levels of the reaction products are very small, but both can dissolve in liquid sodium, and sodium oxide can form compounds with silica. As a consequence, the reaction moves to the right, leading to further reduction of silica. Nevertheless, vitreous silica crucibles have been used sucessfully for containing molten antimony (850°C), copper (1 210°C), gallium (1 100°C), germanium (1 100°C), lead (500°C) and tin (900 C). 

For liquid electrode metals (mercury, gallium) the determination of the surface tension can be applied. From changes of the surface tension as a function of dissolved adsorbable species the surface coverage... 

A liquid metal alloy [36] containing gallium, indium, and tin has been proposed as an additive to Portland cement. A formulation is shown in Table 18-10. The liquid metal alloy has a melting point of 11° C. Its presence does not cause corrosion of stainless steel up to 250° C but causes corrosion of steel alloys at temperature above 35° C, and it dissolves aluminum at room temperature. The alloy is harmless to skin and mucous membranes. 

Al, Ga, In and T1 differ sharply from boron. They have greater chemical reactivity at lower temperatures, well-defined cationic chemistry in aqueous solutions they do not form numerous volatile hydrides and cluster compounds as boron. Aluminium readily oxidizes in air, but bulk samples of the metal form a coherent protective oxide film preventing appreciable reaction aluminium dissolves in dilute mineral acids, but it is passivated by concentrated HN03. It reacts with aqueous NaOH, while gallium, indium and thallium dissolve in most acids. 

By dissolving gallium hydroxide in caustic potash, and electrolyzing the solution with a current from five or six Bunsen cells, Boisbaudran prepared more than a gram of gallium metal. This was first prepared in November, 1875. On December 6th he presented 3.4 milligrams of solid gallium (14) to the Academy of Sciences, and three months later he... 

Potassium amidogaUate, K[Ga(NH2)4], is prepared by dissolving gallium in a solution of KOH in liquid ammonia. Heating this compound to 300 °C under vacuum removes two moles... 

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