Barium metal Subject

Molybdenum salts used as catalysts include cobalt molybdate for hydrogen treatment of petroleum stocks for desulfurization, and phospho-molybdates to promote oxidation. Compounds used for dyes are sodium, potassium, and ammonium molybdates. With basic dyes, phosphomolyb-dic acid is employed. The pigment known as molybdenum orange is a mixed crystal of lead chromate and lead molybdate. Sodium molybdate, or molybdic oxide, is added to fertilizers as a beneficial trace element. Zinc and calcium molybdate serve as inhibitory pigments in protective coatings arid paint for metals subjected to a corrosive atmosphere. Compounds used to produce better adherence of enamels are molybdenum trioxide and ammonium, sodium, calcium, barium, and lead molybdates. 

When we read however, that an alloy of copper, zinc, and barium metal is described as pyrophoric, stable in air we realize that a second meaning, that of producing sparks when ground or abraded, is attached to the word pyrophoric, causing a need for clarification where the word pyrophoric is used without further ampliflcation. Metals and metal alloys of the spark-producing category—borderline cases both of pyrophoric behavior and of pyrotechnic interest—are the subject of this chapter. 

I have found that a mixture of citral and acetone, if it is subjected, in the presence of water, for a suffieiently long time to the action of hydrates of alkaline earths or of hydrates of alkali metals, or of other alkaline agents, is eondensed to a ketone of the formula CjjH pO. This substanee, which I term Pseudo-ionone," may be produced lor instance in shaking together for several days equal parts of citral and acetone with a solution of hydrate of barium, and in dissolving the products of this reaction in ether. 

Greases are also made from soaps of strontium, barium and aluminum. Of these, aluminum-based grease is the most widely used. It is insoluble in water and very adhesive to metal. Its widest application is in the lubrication of vehicle chassis. In industry, it is used for rolling-mill applications and for the lubrication of cams and other equipment subject to violent oscillation and vibration, where its adhesiveness is an asset. 

Metal Halogenates. Dry, finely divided mixtures of red or white phosphorus and chlorates, bromates, or iodates of barium, calcium, magnesium, potassium, sodium, or zinc explode when subjected to friction, impact, or heat. Mixtures of potassium iodate with white or red phosphorus react violently or explosively on addition of a small quantity of water.16... 

This effect mostly occurs with alkali and alkaline earth metals. The low ionisation potentials of these elements cause them to be readily ionised in the flame with a resultant lowering of the population of ground state atoms and a suppression of sensitivity. The technique used to overcome this is to add an easily ionised salt such as potassium chloride to samples and standards. This ionises in preference to the analyte in the flame and enhances sensitivity. As an example, strontium, barium and aluminium are subject to ionisation in the flame. In water analyses, this is suppressed by adding potassium to the samples and standards so that the solution contains 2 000 mg l-1 potassium. 

In 1807, Davy made an important discovery when he subjected slightly moistened potash (potassium carbonate) to electrolysis. He noticed that a silvery matter was deposited at the negative pole, while at the positive pole oxygen was liberated. Davy surmised that the silvery matter observed at the negative pole was of a metallic nature and called it potassium. In similar experiments with sodium hydroxide he also characterized the metal sodium. He then went on to electrolyze the so-called alkaline earths, which led to the isolation of magnesium, calcium, strontium and barium. Davy announced his remarkable discoveries in a series of Bakerian Lectures (he gave all in all no less than five such lectures) and his fame... 

Perchlorates are powerful oxidizing substances. These compounds explode when mixed with combustible, organic, or other easily oxidizable compounds and subjected to heat or friction. Perchlorates explode violently at ambient temperatures when mixed with mineral acids, finely divided metals, phosphorus, trimethylphosphite, ammonia, or ethylenediamine. Explosions may occur when perchlorates are mixed with sulfur, or hydride of calcium, strontium, or barium and are subjected to impact or ground in a mortar. Perchlorates react with fluorine to form fluorine perchlorate, an unstable gas that explodes spontaneously. Heating perchlorates to about 200°C (392°F) with charcoal or hydrocarbons can produce violent explosions. Metal perchlorates from complexes with many organic solvents, which include benzene, toluene, xylenes, aniline, diozane, pyridine, and acetonitrile. These complexes are unstable and explode when dry. Many metal perchlorates explode spontaneously when recrystaUized from ethanol. Saturated solution of lead perchlorate in mathanol is shock sensitive. 

Cowper-Coles found that a soln. of 100 parts of chrome-alum in 100 parts of water with 12 parts of barium sulphate does not yield a deposit of chromium metal on electrolysis. E. Placet found that when a soln. of chrome-alum and an alkali sulphate acidified with sulphuric acid, is electrolyzed, chromium is deposited at the cathode as a hard, bluish-white, lustrous metal, which, under certain conditions, crystallizes in groups resembling the branching of firs. Other metals and alloys— bronze, copper, iron, brass, etc.—may be plated with chromium, and a surface can be obtained to resemble oxidized silver. E. Placet and J. Bonnet have a number of patents on this subject. 

Ionization interferences may be suppressed in two ways. First, a cooler flame may be employed, for example, the alkali metals are little ionized in the cooler air-hydrogen flame. However, this approach is not suitable for the majority of the elements since they are either not determined in cool flames (e.g., the lanthanoids) or subject to solute-volatilization interferences (e.g., barium). The second approach is to shift the ionization equilibrium on the basis of the law of mass action by producing a large excess of electrons in the flame or by charge transfer. In practice, this is simply achieved by adding a large excess of an easily ionized element (e.g., potassium) to both the sample and reference solutions. The effect of this... 

The rare earths (except Eu and Yb) and actinides exhibit strong interactions with many metallic elements, Be and Mg, the late transition elements (columns headed by Mn, Fe, Co and Ni), and with the elements of columns IB to VB. The corresponding phase diagrams exhibit intermetallic compounds. With elements of column lA and column IIA from calcium to barium, comparison of rare earth and actinide thermodynamic behavior is difficult because many phase diagrams are unknown or subject to caution. With early transition metals, rare earths exhibit positive deviations from ideality, characterized in the phase diagram by a miscibility gap in the liquid phase, while actinides are completely miscible in these elements in the liquid state. 

Compotmds of the heavy metals lead, barium, and cadmium are particularly well suited as stabilizers, but are nowadays subject to environmental concerns due to their heavy metal content (1). 

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