Europium II Chloride

The j8-form, unlike the a-form, is only sUghtly soluble in sulfuric acid solution. The mixture containing the dense white europium(II) sulfate is cooled and filtered. The precipitate is washed with dilute hydrochloric acid and then with a few nuUiliters of methyl alcohol containing hydrogen chloride. An atmosphere of carbon dioxide is not required during the filtration. The final product is dried in air at 75°. Yield 4.4 g. (90 per cent). Anal. 99.7 per cent purity (acid iron(III) sulfate-permanganate titration). 

To 300 ml. of a vigorously boiling solution that is normal with respect to sodium carbonate and 0.4 N in sodium hydroxide (12,6 g. NaHCOj -b 10.8 g. NaOH), about 5 g. of dry europium(II) sulfate as prepared above is added gradually. Shortly after the addition, the mixture becomes dark in color but on continued boiling the dark color disappears, and a lemon-yeUow, dense, crystalline precipitate of europium(II) carbonatef forms. The euro-pium(II) carbonate is filtered and dried in air at 75°. Yield 90 per cent. Anal. Nearly 100 per cent (iodine-thiosulfate titration). 

About 3 g. of dry europium(III) chloride in a quartz boatt is introduced into a vitrified quartz tube, and the 

Europium (II) sulfate is a white microcrystaUine salt of density 4.98 at 25°. It is isomorphous with strontium and barium sulfates and is only slightly soluble in water. 

Europium(II) carbonate is a lemon-yellow, dense granular salt that is insoluble in water but soluble in hydrochloric acid. This compound is important because practically any europium(II) compound may be obtained from it by reaction with the appropriate acid. 

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The reduction to the divalent state involves samarium, europium, and ytterbium. In 1906 C. Matignon and E. Gazes obtained samarium(II) chloride by reducing the trichloride with hydrogen. In 1911, G. Urbain and F. Bourion prepared europium(II) chloride by a comparable reduction involving gydrogen, and in 1929 ytterbium(II) chloride was similarly obtained by W. Klemm and W. Schuth. 

Europium (II) acetate, formation of, from europium amalgam, 2 68 Europium(III) acetate, 2 66 citrate solution of, 2 67 Europium amalgams, 2 65, 66, 68n. Europium (II) carbonate, 2 69, 71 Europium(II) chloride, 2 69, 71 formation of, from europium amalgam, 2 68 Europium (III) oxalate, 2 66 Europium (III) oxide, 2 66 Europium (II) salts, 2 69 Europium(II) sulfate, 2 69, 70... 

Purification of Europium. An acetate solution obtained from 20 g. of europium(III) oxide (>99% pure) was treated with 260 ml. of 0.3% sodium amalgam, added in three separate equal portions. The resulting amalgam contained all but 0.09 g. of the europium. Treatment of the amalgam with 100 ml. of 10 M hydrochloric acid caused complete precipitation of europium(II) chloride 2-hydrate. Removal of the product followed by washing with ice-cold 10 M hydrochloric acid and ultimate conversion to euro-pium(III) oxide gave a recovery of spectroscopically pure europium in excess of 90%. 

The purity of a europium preparation may also be checked iodometrically by titrating a europium(II) chloride solution prepared from a weighed portion of the oxide. 

The reduction of europium(III) to europium(II) may be accomplished simply with a Jones reductor or, more elaborately, by the action of hydrogen on the chloride at 700°. In the three procedures below the preparation of (1) europium(II) sulfate, (2) europium(II) carbonate, and (3) europium(II) chloride are described. Fortunately, these europium salts when dry are not appreciably oxidized by dry air and hence may be handled and stored conveniently. The first procedure is based on the preparation of insoluble europium(II) sulfate after reduction of europium(III) in... 

Europium(II) chloride is a white sohd having a bluish cast. Its density is 4.87 at 25°. 

Europium(II) chloride EuClj +26500 Iodine pentoxide I2O5 -79.4... 

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