Preparation of Europium Amalgam

Europium amalgam is very easily prepared by this method. Simultaneously, some potassium amalgam is formed. After the electrolysis, the latter may be removed nearly completely by action of water, which scarcely attacks europium amalgam as long as any potassium amalgam remains. Ytterbium and samarium are the only other rare earth metals that yield amalgams by the electrolysis of their acetate-citrate solutions. The electrical efficiency is high for europium, considerably less for ytterbium, and small for samarium. 

A practical method for the separation of europium (as amalgam) from accompanying rare earths is given below after the description of the method in which the starting material is a pure europium compound. 

To prepare europium(III) acetate from a solution of a soluble europium salt, the oxalate is first precipitated from an acidified dilute solution of a soluble europium(III) salt at 50 to 70° by the slow addition of a 5 per cent solution of oxalic acid while the reaction mixture is stirred. The amorphous precipitate first formed soon becomes crystalline. It is filtered and washed with water and methanol. The product is converted to the oxide by ignition in a muffle furnace at 900°. 

Five grams of europium oxide is dissolved in a small excess (20 ml.) of boiling 25 per cent acetic acid. The con-centa ated acetate solution (which wiU deposit well-formed crystals if cooled) is neutralized with potassium carbonate. 

of citric acid in 64 ml. of water with 21.6 g. of anhydrous potassium carbonate. The solutions of acetate and citrate are mixed, and the resulting solution is made distinctly alkaline to litmus by adding 2.5 g. more of potassium carbonate. 

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