Molten rubidium chloride

Preparation. It is made by the reaction of metallic sodium with hot molten rubidium chloride. 

Mitchell EWJ, Poncet PFJ, Stewart RJ (1976) The ion pair distribution fimctions in molten rubidium chloride. Philos Mag B 34 721-732... 

Bunsen is remembered chiefly for his invention of die laboratory burner umned after him. He engaged in a wide range of industrial and chemical research, including blast-furnace firing, electrolytic cells, separation of metals by electric current, spectroscopic techniques (with Kirchhoff). and production of light metals by electrical decomposition of their molten chlorides. He also discovered two elements, rubidium and cesium. 

The wet oxide reacts explosively with molten aluminum-magnesium aUoys. Violent reaction when heated with powdered aluminum, calcium disilicide, magnesium, metal acetyKdes (e.g., calcium acetyKde + iron(III) chloride (on ignition), cesium acetyKde (incandescent reaction when warmed), rubidium acetyKde). Reacts violently with Al, Ca(OCl)2, N2H4, ethylene oxide. See also IRON and IRON COMPOUNDS. 

A common method for producing rubidium is to pass an electrical current through molten (melted) mbidium chloride ... 

The direct metallothermic reduction of pollucite ore with sodium metal is the primary commercial source of cesium metal. In the process, raw pollucite ore is reduced with sodium molten metal at ca. 650"C to form a sodium-cesium alloy containing some rubidium as impurity. Fractional distillation of this alloy in a distillation column at ca. 700"C produces 99.9 wt.% pure cesium metal. Cesium can also be obtained pyrometallurgiccdly reducing the chloride CsCl with calcium metal or the hydroxide CsOH with magnesium metal. Nevertheless, the electrolytic recovery of a cesium amalgam from an aqueous solution of cesium chloride can be achieved in a process similar to the chlor-alkali production with a mercury cathode. Afterwards, the cesium is removed from the amalgam by vacuum distillation. However, cesium metal is produced in rather limited amounts because of its relatively high cost (US 40,800 /kg)... 

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