Rubidium hydroxide

Rubidium-alaun, m. rubidium alum, -chlorid, n. rubidium chloride, -jodid, n. rubidium iodide, -oxydhydrat, n. rubidium hydroxide, -platinchlorid, n. rubidium chloroplatinate. 

Rubidium hydroxide, 27 821-822 Rubidium iodide, 27 823 Rubidium metal alloys, 27 816 Rubidium metal, pure, 27 818 Rubidium oxides, 27 816, 823 Rubidium ozonide, 78 417 Rubidium silicates, 22 452 Rubidium sulfate, 27 821 Rubidium superoxide, 78 417 Rubidium tetrahydroborate physical properties of, 4 194t Ruby, 2 405 color, 7 329 Ruby glass, 7 344... 

Rubidium hydroxide (RbOH) is very hygj-oscopic (absorbs large amounts of water for its weight). It is also an excellent absorber of carbon dioxide. Rubidium hydroxide can be used to etch glass and as an electrolyte in low-temperature electric storage batteries for use in vehicles in the subarctic. 

The carbonate salt also may be obtained by passing carbon dioxide through a solution of rubidium hydroxide in a fluorocarbon or nickel container. The solution is evaporated to yield the product carbonate. 

Also, the salt may be prepared by adding ammonium carbonate to a solution of rubidium hydroxide. The solution is evaporated to dryness to expel ammonia. 

Rubidium hydroxide is used as a catalyst in oxidative chlorination. It also may be used as a powerful base, stronger than caustic potash, in many preparative reactions. The compound holds promising apphcations as an electrolyte in storage batteries for use at low temperatures. 

Rubidium hydroxide may be obtained as an intermediate in recovering rubidium metal from mineral lepidohte (see Rubidium). In the laboratory it may be prepared by adding barium hydroxide to a solution of rubidium sulfate. The insoluble barium sulfate is separated by filtration ... 

Preparation should be in nickel or silver containers because rubidium hydroxide attacks glass. The solution is concentrated by partial evaporation. The commercial product is usually a 50% aqueous solution. 

Rubidium hydroxide is a stronger base than caustic soda or caustic potash. Its reactions are similar to theirs. Neutralization occurs with acids. Rubidium hydroxide absorbs carbon dioxide forming rubidium carbonate. 

Rubidium sulfate can be prepared by neutralization of a solution of rubidium hydroxide or carbonate with sulfuric acid ... 

Rubidium acid salts are usually prepared from rubidium carbonate or hydroxide and the appropriate acid in aqueous solution, followed by precipitation of the crystals or evaporation to dryness. Rubidium sulfate is also prepared by the addition of a hot solution of barium hydroxide to a boiling solution of rubidium alum until all the aluminum is precipitated. The pH of the solution is 7.6 when the reaction is complete. Aluminum hydroxide and barium sulfate are removed by filtration, and rubidium sulfate is obtained by concentration and crystallization from the filtrate. Rubidium aluminum sulfate dodecahydrate [7488-54-2] (alum), RbA SO 12H20, is formed by sulfuric acid leaching of lepidolite ore. Rubidium alum is more soluble than cesium alum and less soluble than the other alkali alums. Fractional crystallization of Rb alum removes K, Na, and Li values, but concentrates the cesium value. Rubidium hydroxide, RbOH, is prepared by the reaction of rubidium sulfate and barium hydroxide in solution. The insoluble barium sulfate is removed by filtration. The solution of rubidium hydroxide can be evaporated partially in pure nickel or silver containers. Rubidium hydroxide is usually supplied as a 50% aqueous solution. Rubidium carbonate, Rb2C03, is readily formed by bubbling carbon dioxide through a solution of rubidium hydroxide, followed by evaporation to dryness in a fluorocarbon container. Other rubidium compounds can be formed in the laboratory by means of anion-exchange techniques. Table 4 lists some properties of common rubidium compounds. 

Nitric acid HNO3 Rubidium hydroxide RbOH... 

E. Muller made potassium iodate by electrolyzing the iodide. H. L. Wheeler 44 made rubidium iodate, RbI03, by the action of a mol. of iodine pentoxide on one of rubidium carbonate by treating a hot dil. soln. of iodine trichloride with rubidium hydroxide or carbonate by the action of iodic acid on a hot cone. soln. of rubidium chloride, RbCl. T. V. Barker obtained a good yield by passing chlorine into a hot cone. soln. of a mixture of rubidium iodide and hydroxide whereby the sparingly soluble iodate is precipitated. Caesium iodate, CsI03, was made in a similar way. 

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. 

The latent heat ol fusion of sodium hydroxide per gram is 400 cals. potassium hydroxide, 28-6 cals. rubidium hydroxide, 15 8 cals. and csesium hydroxide, 107 cals. The corresponding values in calories per mol. are 1602, 1606, 1614, and 1609 cals, respectively. The heat of transformation of sodium hydroxide per gram is 24 7 cals. potassium hydroxide, 27T cals. rubidium hydroxide, 16 8 cals. and csesium hydroxide, 11 8 cals. The corresponding values in calories per mol. are 990,1522,1702, and 1763 cals, respectively. 

Molten sodium and potassium hydroxides are completely miscible in all proportions, and the f.p. curve has a minimum at 187° with a mixture containing 38 7 atomic percent, of KOH, that is, 48 97 per cent, of KOH by weight. The transformation temp, of the cooling solid alloys furnish a curve similar in form to the f.p. curve, and the solid eutectic has a transformation point at 181°., Mixtures of potassium and rubidium hydroxides are completely miscible, and they give a curve with two maxima-, one rises from the m.p. of potassium hydroxide 360-4° up to 399° with 87 atomic per cent, of KOH, and the other from the m.p. of rubidium hydroxide... 

The rubidium hydroxide of commerce 31 is a monohydrated rubidium hydroxide, RbOH.H20, which melts at 145°, and at 350° it is completely dehydrated to RbOH. At a higher temp, it begins to peroxidize and attack the crucible. The heat of soln. of the monohydrate is 3 702 Cals, at 15°. The commercial csesium hydroxide is likewise a monohydrated csesium hydroxide, Cs0H.H20 it melts at 180°, and is completely dehydrated between 400° and 500°, and at the same time the mass begins to peroxidize. To prepare the pure hydroxide, it must be dehydrated in a current of dry hydrogen at 500°. The heat of soln. of the monohydrate is 4-317 at 15°. 

According to F. A. H. Schreinemakers and A. Filippo,32 100 grms. of an aq. soln. of rubidium hydroxide contain 63 39 grms. RbOH at 30° the corresponding numbers for potassium, sodium, and lithium hydroxides are respectively 55, 76, 54 3, and 11 27. Consequently, the solubilities of the alkali hydroxides increase as the at. wt. of the alkali metal increases. 

Rb2HP04, by the interaction of eq. quantities of rubidium hydroxide and ortho-phosphoric acid in cone, aqua ammonia. The resulting precipitate of ammonia rubidium phosphate loses all its combined ammonia in vacuo over sulphuric acid. E. von Berg prepared hydrated dicsesium hydrophosphate, Cs2HP04.H20, in a similar manner. 

Rubidium Arsenates.8—Rubidium Orthoarsenate, Rb3As04, is prepared by adding a solution of rubidium hydroxide to aqueous arsenic acid until the former is in excess. Very hygroscopic white lamellae of the dihydrate, Rb3As04.2H20, are deposited on evaporation. The salt absorbs carbon dioxide from the air and its solution is alkaline in reaction. When heated, the water of crystallisation is lost at 100° C. 

Less attention has been paid to the reaction of cellulose with rubidium hydroxide and with cesium hydroxide. Heuser and Bartunek101 isolated adducts of rubidium hydroxide and of cesium hydroxide that had the general formula MOH 3 C Hi0Ot. Their studies showed that the concentration, in weight percent, of alkali metal hydroxide required for forming a stable adduct of the lowest alkali content increases with increase in the atomic weight of the metal Li < Na < K < Rb < Cs. However, on a molar basis, this relationship does not hold. No simple relationship exists between the size of cation and the concentration of hydroxide necessary for the formation of a stable adduct. 

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 hydroxide, [CAS 1310-82-3]. RbOH, is the strongest except for cesium hydroxide. CsOH (and francium hydroxide, FrOH), of the alkali hydroxides, as would be expected from its position in the periodic table. For the same reason, it has the next smallest lattice energy (146.6 kilocalories per mole). 

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