Separation calcium

Sulphuric and Oxalic Acids, and Calcium. — Separate 20 cc. portions of the aqueous (1 10) solution of the acid should show no change with barium chloride nor ammonium oxalate solutions nor, when lowered to slight acidity by adding ammonia water, should a precipitate be obtained on adding calcium sulphate solution. 

Calcium separation. Caution. This operation should be conducted in a hood. The calcium isolation equipment consists of a 2-1. three-necked flask equipped with an aircooled condenser, mechanical stirrer, and nitrogen inlet. To the flask is added 11. of methanol and 16 ml. of water, J and a slow nitrogen purge is started. The pieces of calcium-embedded sodium are drained free of mineral oil, washed with kerosine, and added to the methanol at such a rate that only two or three pieces are present in the reaction vessel at one time i.e., the sodium in all but two pieces is permitted to react with the methanol before addition of the next piece of the calcium-embedded sodium. The finely divided calcium is liberated and falls to the bottom as shiny platelets as the sodium matrix reacts with the hydrous... 

An example of calcium separation is the Odda process, in which, depending on the temperature reached, a small part or a large part of the calcium nitrate crystallizes out as its tetrahydrate. The calcium-depleted mother liquor is then neutralized with ammonia. The calcium nitrate separated can, for example, be converted into calcium carbonate and ammonium nitrate by reacting with ammonia and carbon dioxide and then after filtering off the calcium carbonate, worked up to ammonium nitrate ... 

Heavy metals often can be removed effectively by chemical precipitation in the form of carbonates, hydroxides, or sulfides. Sodium carbonate, sodium bisulfite, sodium hydroxide, and calcium oxide are all used as precipitation agents. The solids precipitate as a floe containing a large amount of water in the structure. The precipitated solids need to be separated by thickening or filtration and recycled if possible. If recycling is not possible, then the solids are usually disposed of to a landfill. 

Pu (86 years) is formed from Np. Pu is separated by selective oxidation and solvent extraction. The metal is formed by reduction of PuF with calcium there are six crystal forms. Pu is used in nuclear weapons and reactors Pu is used as a nuclear power source (e.g. in space exploration). The ionizing radiation of plutonium can be a health hazard if the material is inhaled. 

X-ray fluorescence A method of analysis used to identify and measure heavy elements in the presence of each other in any matrix. The sample is irradiated with a beam of primary X-rays of greater energy than the characteristic X-radiation of the elements in the sample. This results in the excitation of the heavy elements present and the emission of characteristic X-ray energies, which can be separated into individual wavelengths and measured. The technique is not suitable for use with elements of lower atomic number than calcium. 

Lead formate separates from aqueous solution without water of crystallisation. It can therefore be used for the preparation of anhydrous formic acid. For this purpose, the powdered lead formate is placed in the inner tube of an ordinary jacketed cond ser, and there held loosely in position by plugs of glass-wool. The condenser is then clamped in an oblique position and the lower end fitted into a receiver closed with a calcium chloride tube. A current of dry hydrogen sulphide is passed down the inner tube of the condenser, whilst steam is passed through the jacket. The formic acid which is liberated... 

Place the distillate in a separating-funnel and extract the benzonitrile twice, using about 30 ml. of ether for each extraction. Return the united ethereal extracts to the funnel and shake with 10% sodium hydroxide solution to eliminate traces of phenol formed by decomposition of the benzenediazonium chloride. Then run off the lower aqueous layer, and shake the ethereal solution with about an equal volume of dilute sulphuric acid to remove traces of foul-smelling phenyl isocyanide (CaHjNC) which are always present. Finally separate the sulphuric acid as completely as possible, and shake the ether with water to ensure absence of acid. Run off the water and dry the benzonitrile solution over granular calcium chloride for about 20 minutes. 

During this period hydrogen chloride continues to be liberally evolved, and the product darkens considerably in colour. Now pour the product cautiously into 500 ml. of dilute hydrochloric acid and 100 g. of chipped ice in a separating-funnel, and shake the mixture thoroughly this operation removes the dark colour, and the toluene solution becomes yellow. Run off the lower acid layer, and extract the toluene three times with water. Finally dry the toluene solution over calcium chloride. 

Dissolve 13 g. of sodium in 30 ml. of absolute ethanol in a 250 ml. flask carrying a reflux condenser, then add 10 g. (9 5 ml.) of redistilled ethyl malonate, and place the flask on a boiling water-bath. Without delay, add a solution of 5 3 g. of thiourea in a minimum of boiling absolute ethanol (about 100 ml.). The sodium salt of thiobarbituric acid rapidly begins to separate. Fit the water-condenser with a calcium chloride guard-tube (Fig. 61, p. 105), and boil the mixture on the water-bath for 1 hour. Cool the mixture, filter off the sodium salt at the pump and wash it with a small quantity of cold acetone. Dissolve the salt in warm water and liberate the acid by the addition of 30 ml. of concentrated hydrochloric acid diluted with 30 ml. of water. Cool the mixture, filter off the thiobarbituric acid, and recrystallise it from hot water. Colourless crystals, m.p. 245 with decomposition (immersed at 230°). Yield, 3 5 -4 0 g. 

Nitrobenzene. Nitrobenzene, of analytical reagent quality, is satisfactory for most purposes. The technical product may contain dinitrobenzene and other impurities, whilst the recovered solvent may be contaminated with aniline. Most of the impurities may be removed by steam distillation after the addition of dilute sulphuric acid the nitrobenzene in the distillate is separated, dried with calcium chloride and distilled. The pure substance has b.p. 210°/760 mm. and m.p. 5 -7°. 

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