Rubidium exposure

The danger of rubidium exposure caused by geological or anthropogenic anomalies hardly exists. The occurrence of the naturally radioactive Rb isotope (27.8%) is interesting at least (Anke and Angelow 1995). 

Reactivity towards air or oxygen increases from lithium to caesium, and the intensity depends on state of subdivision and on presence or absence of moisture. Lithium normally ignites in air above its m.p., while potassium may ignite after exposure to atmosphere, unless it is unusually dry. Rubidium and caesium ignite immediately on exposure [1], It is reported that sodium and potassium may be distilled unchanged under perfectly dried oxygen [2],... 

Rubidium is a typical but very reactive member of the series of alkali metals.lt is appreciably more reactive than potassium, but less so than caesium, and so would be expected to react more violently with those materials that are hazardous with potassium or sodium. Rubidium ignites on exposure to air or dry oxygen, largely forming the oxide. 

In the series of air-sensitive title salts, the potassium, rubidium or caesium salts ignite on exposure to air, and the tetramethyl- or tetraethyl-ammonium salts ignite with violence. 

Properties oi the alkali hydroxides.—The alkali hydroxides are brittle, white, translucent solids with a more or less crystalline fracture, and fibrous texture. Sodium hydroxide deliquesces on exposure to the air, but it goes solid again owing to the formation of the carbonate by the absorption of carbon dioxide from the air. Lithium hydroxide is a little hygroscopic. Potassium hydroxide is even more deliquescent than the sodium compound but its carbonate is also deliquescent. The hydroxides are very solnble in water, and they also dissolve in alcohol. The reported numbers for the specific gravities22 of sodium hydroxide range from l-723 to 2T30 and for potassium hydroxide, from l-958 to 2 6. The best representative sp. gr. are 2"54 for lithium hydroxide 2130 for sodium hydroxide 2 044 for potassium hydroxide 3"203 (11°) for rubidium hydroxide and 3-675 (11°) for csesium hydroxide. 

Chemical properties.—Sodium chloride is necessary for the proper performance of the physiological functions of the body the other alkali chlorides are said to be poisonous 64 with small animals. According to C. Richet, the maximum dose per kilogram of animal, with subentaneous injections, is 01 grm. with lithium chloride 0 5 grm. with potassium chloride l O grm. with rubidium chloride and 0 5 grm. with caesium chloride. Lithium chloride is very hygroscopic sodium chloride is less hygroscopic, but it takes up O 5 to 0> 6 per cent, moisture on exposure... 

Anhydrous lithium nitrate is very deliquescent and sodium nitrate is also deliquescent. Since the last-named salt becomes damp on exposure to the air it cannot be used for some purposes for which potassium nitrate is applicable. Potassium, rubidium, and caesium nitrates do not deliquesce under the same conditions, although G. J. Mulder43 showed that if potassium nitrate be confined under a bell-jar over water at 14° to 20°, it does deliquesce and E. L. Kortright found the same salt at 20° to deliquesce when the partial press, of the water vapour exceeds 15 5-16 5 mm., and sodium nitrate when the partial press, of the water vapour exceeds 123-135 mm. A salt can be deliquescent only when the press, of the water vapour from its sat. soln. exceeds the partial press, of the water vapour in the surrounding air. If pi be the vap. press, of water, p, the vap. press, of a sat. soln. of the salt containing S grms. of salt pet 100 grms. of water, and k be the constant of proportion to be evaluated from the observed data, R. Emden has shown that Sk=(p—pi)/p, which enables p% to be computed from the values of p and S. The deliquescence press, of the water vapour for sodium nitrate at 0°, 10°, 20°, and 30° is then 3 5, 6 9, 12 8, and 22 6 mm. respectively, and for potassium nitrate, 4 4, 8 7, 16 0, and 28 3 mm. respectively. 

Rubidium Niobates.—When niobium pentoxide is fused with rubidium carbonate and the melt is extracted with water, fine, silky needles of composition 3Rb20.4Nb205.9 Ha0 are left behind. Concentration of the filtrate yields monoclinic crystals of 4Rb20.3Nba0B. 14H20, which are isomorphous with the corresponding tantalum salt and with the corresponding caesium niobate and tantalate. a b c= 0-8815 1 1-0491 j3=95° 53. It slowly loses some of its water on exposure to- air.3... 

Rubidium is a silver-white, very soft metal tarnishes instantly on exposure to air, soon ignites spontaneously with flame to form oxide best preserved in an atmosphere of hydrogen rather than in naphtha reacts vigorously with H2O forming rubidium hydroxide solution and hydrogen gas, Discovered by Bunsen and Kirchhoff m 1860 by means of the spectroscope. 

Rubidium is more electropositive than potassium (or the lower alkali metals) as is consistent with its position in main group 1. It reacts more vigorously with H O, and ignites on exposure ro oxygen. 

This accounts for 27% of xenon. It is activated by exposure to laser-stimulated rubidium atoms which transfer energy to the xenon atoms, thereby enabling them to be viewed by MRI. 

---