Solution aqueous cobalt chloride

Modras (51) reported spot test reactions to differentiate hydralazine from closely related drugs. Reagents used were aqueous copper (I) chloride, aqueous ammonium molybdate, iodine in potassium iodide solution, aqueous cobalt (II) nitrate, alcoholic ninhydrin, and alcoholic bromophenol blue. The tests were performed on paper or on Silica Gel G. 

Hexammino-cobaltous Chloride, [Co(NH3)6]C12, is the most stable of the three ammines of cobaltous chloride and may be prepared in aqueous solution. If ammonia gas be passed into a concentrated aqueous solution of cobaltous chloride the greenish precipitate at first formed dissolves in excess of ammonia in absence of air, giving a red solution. From the liquid, on standing, pale red octahedral crystals of pentammino-cobaltous chloride separate. The crystals are stable in absence of air but lose ammonia if kept over sulphuric acid. On heating to 120° C. the substance loses four molecules of ammonia and is transformed into diammino-cobaltous chloride. It is soluble in aqueous ammonia without decomposition and insoluble in alcohol. With platinous chloride it forms a double salt, [Co(NH3)3]PtCl4.3 Cobaltous... 

The acid chloride, [Co en2Cl2]Cl.HC1.2H20, is formed by mixing a solution of cobaltous chloride with an aqueous solution of ethylene-diamine monohydrate and oxidising the mixture with air. Concentrated hydrochloric acid is then added and the whole heated on a water-bath for one hour. The liquid is allowed to stand, when crystals separate, and are filtered and washed with concentrated hydrochloric acid.2 The salt crystallises in dark green rhombic plates. It is soluble in water, though less soluble than the normal salt, and on heating to 100° C. is transformed into the normal salt. 

Most authorities attribute the discovery of the first metal ammine to Tassaert, a Parisian chemist about whom virtually nothing is known — not even his first name. In his short article12 he is identified only as Citoyen Tassaert — Citizen Tassaert. Some chemists imply or even openly state that Tassaert was the first to prepare hexaamminecobalt(III) chloride, [Co(NH3)6]C13, the parent compound from which all cobalt ammines may be considered to be derived. Yet he merely observed the brownish mahogany color of the solution formed when excess aqueous ammonia is added to a solution of cobalt chloride or cobalt nitrate, and he failed to follow up his accidental discovery. 

The only definite borate hydrates of cobalt are the CoO - 3B203 - 8H20 and CoO 3B203 10H2O compounds. The octahydrate is prepared by evaporation of acetic acid from cobalt acetate-boric acid mixtures, or by mixing aqueous solutions of cobalt chloride, borax, and boric acid (206). The 1 3 7.5 borate can form as a solid solution and, in the presence of 3% boric acid, affords the decahydrate (117). The crystal structure determination of this 1 3 10 compound shows it to possess the hexaborate ion (380). The IR spectra (402) and thermal decomposition (396) of these compounds have been determined. 

The hemmmoniate, CoC12.6NH3, is produced by passing ammonia into a concentrated aqueous solution of cobalt chloride in the entire absence of air,3 or by passing it into a saturated solution of cobalt chloride in methyl acetate.4 It yields dark rose-red octahedral crystals. 

Cobalt Oxy-chloride is obtained as a blue precipitate turning red on pouring a hot solution of cobalt chloride into dilute ammonium hydroxide. The formula CoCl2.3Co0.3-5H20, has been attributed to it.1 Another basic salt, CoC.]2.Co(OH)2.5H20, is stated to result as a precipitate by the action of calcium carbonate upon aqueous solutions of cobalt chloride.2... 

Anisole treated with an aqueous solution of cobaltous chloride and potassium cyanide in the presence of oxygen gave negligible amounts of methoxyphenols. 

Another point that is demonstrated by Fig. 20 is that the sudden increase in absorbance (the solution becomes black) is the fastest in aqueous solution, slowest in the microemulsion sample, and of intermediate rate in the ethanolic solution of cobalt chloride. This illustrates the two-step mechanism in particle formation, i.e., reactant dissolution or dispersion first and reduction reaction afterward. 

Cobalt chloride, C0CI2. Obtained as red crystals of CoCl2 6H20 from aqueous solution, CoCU HiO and C0CI2 are blue as is the (CoCU) " ion. No higher chloride is known although cobalt-haloammines, e.g. (Co(NH3)5C1) are stable. 

Arsonium salts have found considerable use in analytical chemistry. One such use involves the extraction of a metal complex in aqueous solution with tetraphenyiarsonium chloride in an organic solvent. Titanium(IV) thiocyanate [35787-79-2] (157) and copper(II) thiocyanate [15192-76-4] (158) in hydrochloric acid solution have been extracted using tetraphenyiarsonium chloride in chloroform solution in this manner, and the Ti(IV) and Cu(II) thiocyanates deterrnined spectrophotometricaHy. Cobalt, palladium, tungsten, niobium, and molybdenum have been deterrnined in a similar manner. In addition to their use for the deterrnination of metals, anions such as perchlorate and perrhenate have been deterrnined as arsonium salts. Tetraphenyiarsonium permanganate is the only known insoluble salt of this anion. 

Table 2.25 Breakdown potentials for 316S12 stainless steel (cold worked), high nitrogen stainless steel (cold worked), titanium-6Al-4V and cast-cobalt-chromium-molybdenum alloy in continuously aerated aqueous acidified chloride solution 0.23 m [C1 ] pH 1.5 at 25°C. ...

It is very common for inorganic chemists to neglect or ignore the presence of solvent molecules coordinated to a metal centre. In some cases, this is just carelessness, or laziness, as in the description of an aqueous solution of cobalt(ii) nitrate as containing Co ions. Except in very concentrated solutions, the actual solution species is [Co(H20)6] . In other cases, it is not always certain exactly what ligands remain coordinated to the metal ion in solution, or how many solvent molecules become coordinated. Solutions of iron(iii) chloride in water contain a mixture of complex ions containing a variety of chloride, water, hydroxide and oxide ligands. 

While cobalt(II) fluoride is the product of the reaction of anhydrous cobalt(ll) chloride with hydrofluoric acid, cobalt(lll) fluoride is obtained from fluorina-tion of an aqueous solution of cobalt(ll) chloride. 

These salts are formed from dilute ammoniacal solutions of cobaltous salts in air, or by heating aquo-pentammino-salts with ammonia. Frequently they are obtained as decomposition products of acido-pentammino-salts. They may be obtained directly from the corresponding cobaltous salt by heating with excess of ammonia and ammonium chloride,2 or from the corresponding ammonium salt by addition of lead peroxide to the aqueous solution. 

Hexammino - cobaltic Chloride, or Luteo-cobaltic Chloride, [Co(NH3)8]Cl3.—Several methods of preparation have been described. The best method is that of Jorgensen,1 whereby the salt is prepared by warming chloro-pentammino-cobaltic chloride, [Co(NH3)5C l]Cl2. in a pressure flask with 20 per cent, aqueous ammonia and ammonium chloride for several hours with constant shaking. After cooling, the mixture is removed from the flask and ammonia allowed to evaporate. The liquid is then diluted, hydrochloric acid added, and the whole heated on the water-bath, thus changing any aquo-pentammino-chloride into ehloro-pentammino-ehloride. More concentrated hydrochloric acid is added and the mixture cooled and filtered. The residue on the filter consists of ammonium chloride, chloro-pentammino-chloride, and hexammino-cobaltic chloride. Ammonium chloride is removed by treating with a 20 per cent, solution of hydrochloric acid, and the residue is then treated on a filter with cold water in which chloro-pentammino-cobaltic chloride is insoluble and hexammino-cobaltic chloride soluble. The salt is precipitated from its warm solution by the addition of half its volume of concentrated hydrochloric acid. 

The aquo-salts generally readily pass into the acido-ammino salts for example, aquo-pentammino-eobaltic chloride and diaquo-tetram-mino-cobaltic chloride are transformed into ehloro-pentammino-cobaltic chloride and dichloro-tetrammino-cobaltie chloride respectively on leaving concentrated aqueous solutions to stand for some time. 

The chloride, [Co(NIi3)5OH]Cl2.H20, is formed from aquo-pentammino-cobaltic chloride by dissolving it-in aqueous ammonia, warming the solution and mixing it with alcohol. It separates as a crystalline meal, and is purified by redissolving it in ammoniacal solution and adding alcohol. It crystallises in glistening scales and has similar properties to the nitrate. 

The bromide, [Co en2H20.0H]Br2.H20, is obtained from the chloride or from iraws-dichloro-diethylenediamino-cobaltic chloride by treating it with concentrated aqueous potassium hydroxide and, after cooling to 0° C., neutralising the solution obtained with concentrated hydrobromie acid. It is a red crystalline powder, and resembles the chloride in properties. 

The salt crystallises in large brownish-yellow monoclinic crystals, which are very sparingly soluble in cold water. If the neutral aqueous solution is heated it decomposes, as does the slightly acid solution. Excess of hydrochloric acid transforms it into chloro-pentammino-cobaltic chloride. 

More complex salts are also known belonging to the series. For instance, if a solution of nitro-pentammino-cobaltic chloride be treated with an aqueous solution of sodium cobaltic nitrite, Na3Co(N02)6, a yellowish-brown crystalline precipitate of nitro-pentammino-cobaltic cobalti-nitrite, [Co(NH3)5(N02)]3[Co(N02)6]2, is formed. Also the corresponding ferrocyanicle may be prepared by treating nitro-pentammino-salts with potassium ferrocyanide. The compound obtained is a reddish-yellow substance of composition [Co(NH3)5(NO,)], [Fe(CN )6].6H20. 

Chloro-pentammino-cobaltic chloride forms carmine-red rhombic crystals which are slightly soluble in water, insoluble in water containing hydrochloric aeid or ammonium chloride, and insoluble in alcohol. The aqueous solution is decomposed on warming, and the compound,... 

It separates in small violet rhombic crystals which resemble chloro-pentammino-cobaltic chloride in appearance. It is soluble in cold water to a certain extent, and only two-thirds of the chlorine is precipitated from solution by silver nitrate at ordinary temperature. In aqueous solution the salt is gradually transformed into the diaquo-salt, [Co(NH3)4(HaO)2]Cl3 dilute nitric acid, if rubbed with the substance, gives reddish-violet crystals of the nitrate, [Co(XH3)4(HaO)Cl](NOs)2 and a cold concentrated solution of ammonium sulphate yields the sulphate, [Co(NH3)4(H20)C1]S04. The corresponding bromide, [Co(NH3)4(H2Q)Cl]Br2, is obtained by filtering a cold saturated solution of the chloride into concentrated hydrobromie acid at 0° C. The precipitate formed is washed with hydrobromie acid and then with alcohol. The bromide is almost insoluble in hydrobromie acid, but more easily soluble in water than the chloride.2... 

Dinitro-tetrammino-cobaltic Chloride, [Co(NH3)4(N03)2] Cl, is obtained from the sulphate by treating it with barium chloride, or by heating a solution of dichloro-tetrammino-cobaltic ehloride in dilute acetic acid with sodium nitrite.3 It is soluble in water, and separates from solution in reddish-yellow rhombic crystals. The aqueous solution, however, decomposes on standing. If a cold aqueous solution be treated with dilute nitric acid the nitrate separates concentrated hydrochloric acid decomposes the salt with formation of the chloro-nitro-chloride, [Co(NH3 )4 (NO 2)C1] Cl.3... 

Oxalato-tetrammino-cobaltic Chloride, [Co(NH3)4(C204)]C1, is prepared by dissolving chloro-aquo-tetrammino-eobaltic chloride in an aqueous solution of oxalic acid and heating the mixture for some time. The oxalato-compound gradually crystallises from the warm solution, and the crystals are collected and washed on the filter with alcohol until the filtrate is free from chlorine and from oxalic acid. It crystallises in carmine-red six-sided plates if dissolved in concentrated sulphuric acid and concentrated hydrochloric acid is added to the liquid, it is transformed into dichloro-tetrammino-cobaltic chloride. Sodium nitrite and acetic acid convert it into dinitro-tetrammino-cobaltic chloride.1... 

The crude substance is their recrystallised from water containing acetic acid. The compound was originally believed to exist in two isomeric forms, but Jorgensen found the crystalline form depends on the concentration of acetic acid used for crystallisation, inasmuch as rhombic leaflets separate from hot dilute acetic acid, and from hot concentrated acid the substance separates in yellow-brown needles. The complex is sparingly soluble in water, and gives no precipitate in aqueous solution with silver nitrate or potassium chromate. If treated with cold hydrochloric acid it is transformed into chloro-dinitro-triammino cobalt, [Co(NH3)3(N02)2Cl], and if warmed with concentrated hydrochloric acid gives diehloro-aquo-triammino-cobaltic chloride. 

Ammonium Tetranitrito - diammino - cobaltate, [Co(XH3)2 (N02)4]NH4, is prepared from cobaltous chloride by mixing an aqueous solution of the salt with aqueous ammonium-chloride solution, sodium nitrite, and ammonia, and oxidising the mixture by passing air through it for several hours. The solution is allowed to stand in air for some days, when crystals gradually separate. These are collected, washed, and reerystallised from water.3 The substance crystallises in brown rhombic prisms. It is decomposed on treatment with potassium hydroxide with evolution of ammonia, and a cold solution reacts with ammonia in presence of ammonium salts, with formation of flavo-dinitro double salts, of which [Co(NH3)4(N02)2][Co(NH3)2(N02)4] is typical. Oxalic acid transforms it into the oxalato-dinitrito-diammino-salt, [Co(NH3)2(N02)2(C204)]NH4. 

Potassium Tetranitrito - diammino - cobaltate, [Co(NH3)3 (N02)4]K.—The salt is produced by treating cobaltous chloride with excess of ammonium chloride and potassium nitrite, and warming the liquid to 50° C. It is then allowed to stand at low temperature for several hours, when crystals separate. They are dissolved in boiling water, filtered. and cooled, when lustrous browm rhombic crystals separate. The salt may be obtained from the ammonium salt by treating a warm aqueous solution with potassium acetate. 

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