Metal with hydrogen

Potassium Hydride. Potassium hydride [7693-26-7] KH, made from reaction of molten potassium metal with hydrogen at ca 200°C, is suppHed in an oil dispersion. Pressure Chemical Company (U.S.) is a principal suppHer. KH is much more effective than NaH or LiH for enolization reactions (63,64). Use of KH as a base and nucleophile has been reviewed (65). 

Barium is a member of the aLkaline-earth group of elements in Group 2 (IIA) of the period table. Calcium [7440-70-2], Ca, strontium [7440-24-6], Sr, and barium form a closely aUied series in which the chemical and physical properties of the elements and thek compounds vary systematically with increa sing size, the ionic and electropositive nature being greatest for barium (see Calcium AND CALCIUM ALLOYS Calcium compounds Strontium and STRONTIUM compounds). As size increases, hydration tendencies of the crystalline salts increase solubiUties of sulfates, nitrates, chlorides, etc, decrease (except duorides) solubiUties of haUdes in ethanol decrease thermal stabiUties of carbonates, nitrates, and peroxides increase and the rates of reaction of the metals with hydrogen increase. 

Other hydrides with interstitial or metallic properties are formed by V, Nb and Ta they are, however, very much less stable than the compounds we have been considering and have extensive ranges of composition. Chromium also forms a hydride, CrH, though this must be prepared electrolytically rather than by direct reaction of the metal with hydrogen. It has the anti-NiAs structure (p.. 555). Most other elements... 

The catalytic activity of the pure /3-palladium hydride has been studied under the appropriate temperature and pressure conditions. The palladium sample was converted into the hydride in a manner which bypassed the area of coexistence of the phases. This was achieved by suitably saturating the metal with hydrogen at 35 atm above the critical temperature and then subsequently cooling the sample to the required temperature and reducing the hydrogen pressure. This method of sample prepare tion allowed one to avoid cracking the palladium crystallites, which would... 

Pauling, L. (1977) "The nature of bonds formed by the transition metals with hydrogen, carbon, and phosphorus," Acta Crystal-logr., in press. 

Pauling, L. Nature of the Bonds Formed by the Transition Metals with Hydrogen, Carbon, and Phosphorus Acta Crystallogr. 1978, B34, 746-754. 

During the traditional qualitative inorganic analytical procedure, samples containing the lead and salicylate radicals can lead to the formation and possible detonation of lead picrate. This arises dining evaporation of the filtrate with nitric acid, after precipitation of the copper-tin group metals with hydrogen sulfide. Salicylic acid is converted under these conditions to picric acid, which in presence of lead gives explosive lead picrate. An alternative (MAQA) scheme is described which avoids this possibility. 

Lithium hydride is prepared by heating lithium metal with hydrogen above 440°C. The reaction is exothermic and can be controlled once it is initiated, without external heating. The heat of formation is greater than that of sodium hydride ... 

Also, the hydride may be prepared by heating tianium metal with hydrogen at elevated temperatures. 

Uranium forms two stable fluorides, UF4 and UFe. When metal is heated with fluorine gas, hexafluoride, UFe, is produced. Heating powdered metal with hydrogen fluoride gas at 350°C yields tetrafluoride, UF4. Powdered metal is obtained by thermal decomposition of trihydride, UH3. Uranium combines with chlorine at elevated temperature (at about 500°C) to form a mixture of various chlorides namely, the tetrachloride, UCI4, pentachloride, UCI5, and hexachloride,UCl6. Heating the metal with bromine vapor at 650°C forms tetrabromide, UBr4. Uranium also forms tri-and pentabromides. With... 

Hydride also may be obtained by combining zirconium metal with hydrogen... 

The element is obtained primarily from the two commercially important ores, scheelite (CaW04) and wolframite [(Fe,Mn)W04]. W03 is produced from these ores and then reduced to the metal with hydrogen.5... 

All of die halides except tile hexafluoride and the triiodide may be prepared by the hydrohalogenation of rhe dioxide or of the oxalate of plutonium(lll) at a temperature of about 700°C. With hydrogen fluoride the reaction product is PUF4, unless hydrogen is added to the gas stream, in which case the trifluoride is produced. With hydrogen iodide the reaction product is PuOi, and the other oxyhalides may be formed by the addition of appropriate quantities of water vapor to the hydrogen halide gas. Plutonium triiodide is produced by the reaction of the metal with hydrogen iodide at about 400°C. The hexafluoride is produced by direct combination of the... 

To reduce the number of unknown parameters of the model, it was assumed [203] that the dependence (Jmm( h) can be determined from existing experimental data [200,212]. Fig. 8.13 compares the shear modulus for two limiting states of the membrane matrix equilibrium (rj) and nonequilibrium (77 ). The model proposed qualitatively agrees with few reliable experimental data on the effect of dissolved hydrogen on the mechanical modules. It correctly predicts the decrease in both Young s modulus and sheer modulus during the saturation of the metal with hydrogen in a wide... 

They are usually produced by the reaction of metal with hydrogen. Besides the formation of true hydride phases, hydrogen also dissolves in the metal to give a solid solution. 

Lithium hydride is formed by first reducing a lithium compound to lithium and then contacting liquid lithium metal with hydrogen above the melting point of lithium hydride... 

Extraction of manganese, like other redox metals, with hydrogen peroxide is pH dependent. Hydrogen peroxide acts as a reductant in acid but oxidant in alkali, whereas Caro s acid shows oxidizing behaviour throughout the pH range (Figure 6.10). 

The nickel-cobalt sulfides as a suspension in dilute sulfuric acid are oxidized in agitated, spherical autoclaves at 350°F in the presence of air at 500 psig and excess sulfides. The unleached solids in the thickener overflow are recycled back to the autoclave and the liquor, containing 50 gm/liter Ni, 5 gm/liter Co as sulfates and small amounts of iron, aluminum, chromium, copper, zinc, and lead, is purified. The iron, aluminum, and chromium are precipitated as the hydroxides by adjusting the pH to 5.5 with ammonia and the copper, lead, and most of the zinc are removed by subsequent addition of sulfuric acid to lower the pH to 1.5 and precipitation of the metals with hydrogen sulfide. 

In a rather formal way the hydrides of thorium and uranium fall within the scope of this review. The thorium hydrides have been known for many years. They are obtained by the direct reaction of the metal with hydrogen. 

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