Beryllium alkaline solutions

The standard reduction potential for Be2+ is the least negative of the elements in the group and by the same token beryllium is the least electropositive and has the greatest tendency to form covalent bonds. The bulk metal is relatively inert at room temperature and is not attacked by air or water at high temperatures. Beryllium powder is somewhat more reactive. The metal is passivated by cold concentrated nitric acid but dissolves in both dilute acid and alkaline solutions with the evolution of dihydrogen. The metal reacts with halogens at 600°C to form the corresponding dihalides. 

Between pH values of ca. 6 and 12 aqueous solutions hold very little dissolved beryllium because of the low solubility of Be(OH)2. When the pH is raised above 12, the hydroxide begins to dissolve with the formation of, first, Be(OH)3 and then, at even higher pH values, Be(OH) (52). The presence of these species in strongly alkaline solutions was confirmed by means of solvent extraction experiments (90) and infrared spectroscopy (31). A speciation diagram is shown in Fig. 7, which was constructed using the values of log /33 = 18.8 and log /34 = 18.6 critically selected from Table III. The diagram illustrates clearly the precipitation and dissolution of Be(OH)2. 

Beryllium hydroxide is prepared by treating basic beryllium acetate, Be40(C2H302)e with caustic soda solution or by precipitation from a strongly alkaline solution of sodium beryllate. The precipitate is dried at 100°C. 

Arfwedson fused the chrysoberyl three times with caustic potash in a silver crucible. Since a portion of the melt corresponding to about 18 per cent of the mineral failed to dissolve in hydrochloric acid, he reported this residue as silica. It is now known that beryllium hydroxide, when freshly precipitated, dissolves readily in hydrochloric acid, but becomes after a time almost completely insoluble in it (17). Therefore, it is probable that Arfwedson s silica was really the beryllium hydroxide. He then precipitated the alumina by adding ammonium hydroxide to the acid filtrate. To satisfy himself of the purity of his alumina, he saturated the alkaline solution with hydrochloric acid until the precipitate dissolved, and added a large excess of ammonium carbonate. Had any glucina [beryllia] or yttria existed in the matter, said Arfwedson, it would have been dissolved by this excess of carbonate of ammonia, and would have fallen when the filtered liquid was boiled till the excess of ammonia was driven off but the liquid stood this test without any precipitate appearing. Arfwedson was evidently unable to detect beryllia here because he had already filtered it off and reported it as silica. When American chemist Henry Seybert analyzed the same mineral in 1824 he found it to contain 15 to 16 per cent of beryllia (22). 

Quinalizarin reagent cornflower-blue colouration with faintly alkaline solutions of beryllium salts. The reagent alone gives a characteristic violet colour with dilute alkali but this is quite distinct from the blue of the berryllium complex a blank test will render the difference clearly apparent. 

Medieval alchemists classified solids that did not melt in their fires as earths. Group 2A elements form compounds with oxygen, called oxides, that qualify as earths by this definition. Except for beryllium oxide, these oxides produce alkaline solutions when they react with water. The label alkaline earth reflects these two properties. 

Beryllium oxide (BeO) is an extremely hard substance, much more so than the oxides of the other alkaline earths. Beryllium hydroxide (Be(OH)2) is an amphoteric compound, meaning that it is soluble in both acidic and basic solutions. In hydrochloric acid, the following reaction takes place ... 

The Group 2A(2) elements are called alkaline earth metals because their oxides give basic (alkaline) solutions and melt at such high temperatures that they remained as solids ( earths ) in the alchemists fires. The group includes rare beryllium (Be), common magnesium (Mg) and calcium (Ca), less familiar strontium (Sr) and barium (Ba), and radioactive radium (Ra). The Group 2A(2) Family Portrait presents an overview of these elements. 

The addition of soluble carbonates to beryllium salt solutions gives only basic carbonates. Beryllium salt solutions also have the property of dissolving additional amounts of the oxide or hydroxide. This behavior is attributable to the formation of complex species with Be—OH—Be or Be—O—Be bridges. The rapidly established equilibria9 involved in the hydrolysis of the [Be(H20)4]2+ ion are very complicated and depend on the nature of the anion, the concentration, the temperature, and the pH. The main species, which will achieve 4-coordination by additional water molecules, are considered to be Be2(OH)3+, Be3(OH)3+ (probably cyclic) and possibly Bes(OH)3+. Various crystalline hydroxo complexes have been isolated.6 In concentrated alkaline solution the main species is [Be(OH)4]2. ... 

In Fig. 9.13, the heat treatments are necessary to improve the efficiency of the sulphation step. The latter can be engineered in several alternative types of plant. Alternatives are available for the subsequent steps to pure oxide, but usually based upon precipitation and crystallization, as is the one shown in Fig. 9.13. The precipitation of beryllium hydroxide by boiling an alkaline solution of sodium beryllate, is a particularly valuable purification step, and is also used in Fig. 9.14. Chlorination of oxide mixed with carbon is a standard type of operation as used for the preparation of chloride intermediates of other metals. Molten salt electrolysis is one of the two alternative commercial routes to pure beryllium metal, the other being shown in Fig. 9.14. 

This test is affected by large amounts of ammonium salts they should be removed beforehand. Aluminum, in not too great excess, lead, zinc, and antimony salts do not interfere. Solutions of copper and nickel salts can be decolorized by adding potassium cyanide, whereas cobalt salts form the Light yellow soluble potassium cobalticyanide K3[Co(CN) ], which does not interfere with the recognition of the blue of the quinalizarin compound. Iron salts may be masked by means of tartrates. However, tartrates interfere if aluminum is present because a red color is formed in the caustic alkaline solution of quinalizarin. If both iron and aluminum are present, the test solution should be treated with 5 ml of 1 iV NaOH, cooled, diluted to 15 ml, and then filtered if necessary. The dear solution contains any beryllium as beryllate and can be tested as described below. 

Procedure. A drop of the test solution is mixed on the spot plate with a drop of freshly prepared alkaline solution of quinalizarin. For very small amounts of beryllium, an alcoholic solution of the dyestuff may be used. A drop of dilute ammonia or alkali is then added. A blue color (compared with a blank) indicates the presence of beryllium larger amounts yield a blue precipitate. 

Procedure, A drop of the alkaline solution of the dyestuff is placed on filter paper, and the tip of a capillary containing the test solution is touched to the middle of the yellow area so that the liquid runs slowly into the paper. The spot is then treated with a further drop of reagent. In the presence of beryllium. 

Feldman I, Neuman WF, Dankey KA, Havill JR (1951) The beryllium-citrate system. I. Dialysis studies in alkaline solution. J Am Chem Soc 73 4775-4777 Topolski A (2011) Insight into the degradation of a manganese(III)-citrate complex in aqueous solutions. Chem Papers 65 380-392... 

Aluminium and beryllium hydrides react with water in the same way as the salt-like hydrides, to give hydrogen and metal hydroxides. However, the hydroxides are insoluble, so alkaline solutions are not produced for example... 

Discussion. Some of the details of this method have already been given in Section 11.11(C), This procedure separates aluminium from beryllium, the alkaline earths, magnesium, and phosphate. For the gravimetric determination a 2 per cent or 5 per cent solution of oxine in 2M acetic add may be used 1 mL of the latter solution is suffident to predpitate 3 mg of aluminium. For practice in this determination, use about 0.40 g, accurately weighed, of aluminium ammonium sulphate. Dissolve it in 100 mL of water, heat to 70-80 °C, add the appropriate volume of the oxine reagent, and (if a precipitate has not already formed) slowly introduce 2M ammonium acetate solution until a precipitate just appears, heat to boiling, and then add 25 mL of 2M ammonium acetate solution dropwise and with constant stirring (to ensure complete predpitation). 

Discussion. Minute amounts of beryllium may be readily determined spectrophotometrically by reaction under alkaline conditions with 4-nitrobenzeneazo-orcinol. The reagent is yellow in a basic medium in the presence of beryllium the colour changes to reddish-brown. The zone of optimum alkalinity is rather critical and narrow buffering with boric acid increases the reproducibility. Aluminium, up to about 240 mg per 25 mL, has little influence provided an excess of 1 mole of sodium hydroxide is added for each mole of aluminium present. Other elements which might interfere are removed by preliminary treatment with sodium hydroxide solution, but the possible co-precipitation of beryllium must be considered. Zinc interferes very slightly but can be removed by precipitation as sulphide. Copper interferes seriously, even in such small amounts as are soluble in sodium hydroxide solution. The interference of small amounts of copper, nickel, iron and calcium can be prevented by complexing with EDTA and triethanolamine. 

Preparation and Properties of Beryllium Hydroxide. Add a 10% ammonia solution dropwise to 4-5 ml of a 3% beryllium sulphate solution up to the complete formation of a precipitate. See how beryllium hydroxide reacts with 10% solutions of sodium hydroxide (use a minimum amount of the alkali) and acids. Boil the alkaline... 

Solutions of alkali metals in ammonia have been the best studied, but other metals and other solvents give similar results. The alkaline earth metals except- beryllium form similar solutions readily, but upon evaporation a solid ammoniste. M(NHJ)jr, is formed. Lanthanide elements with stable +2 oxidation states (europium, ytterbium) also form solutions. Cathodic reduction of solutions of aluminum iodide, beryllium chloride, and teUraalkybmmonium halides yields blue solutions, presumably containing AP+, 3e Be2, 2e and R4N, e respectively. Other solvents such as various amines, ethers, and hexameihytphosphoramide have been investigated and show some propensity to form this type of solution. Although none does so as readily as ammonia, stabilization of the cation by complexation results in typical blue solutions... 

The salts of the alkali and alkaline earth metals, as well as of gold, magnesium, beryllium and yttrium, are soluble in water, the solutions being colourless or pale yellow. They gradually decompose, however, when kept, with deposition of sulphur, arsenic and arsenic pentasulphide. The following thioarsenates have been described. 

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