Sulphate chromic

Violet Chromium Sulphates.—Chromic sulphate can be obtained in aqueous solution by dissolving chromic hydroxide (dried at 100° C.) in the calculated quantity of warm sulphuric acid, allowing the green solution to stand for a week, when it becomes blue in colour (although... 

With ammonium sulphate, chromic sulphate forms the double salts, 3(NHJ.2S0,.Cr2(S04)3 and (NHi)2S04.Cr2(S0j3, besides the alum,... 

CAUTION. Ethers that have been stored for long periods, particularly in partly-filled bottles, frequently contain small quantities of highly explosive peroxides. The presence of peroxides may be detected either by the per-chromic acid test of qualitative inorganic analysis (addition of an acidified solution of potassium dichromate) or by the liberation of iodine from acidified potassium iodide solution (compare Section 11,47,7). The peroxides are nonvolatile and may accumulate in the flask during the distillation of the ether the residue is explosive and may detonate, when distilled, with sufficient violence to shatter the apparatus and cause serious personal injury. If peroxides are found, they must first be removed by treatment with acidified ferrous sulphate solution (Section 11,47,7) or with sodium sulphite solution or with stannous chloride solution (Section VI, 12). The common extraction solvents diethyl ether and di-tso-propyl ether are particularly prone to the formation of peroxides. 

Skin Inorganic acids (chromic, nitric) organic acids (acetic, butyric) inorganic alkalis (sodium hydroxide, sodium carbonate) organic bases (amines) organic solvents. Dusts Detergents salts (nickel sulphate, zinc chloride) acids, alkalis, chromates. ... 

By oxidising sparteine sulphate with chromic acid, Willstatter and Marx obtained spartyrine, Ci5Hg4Ng (m.p. 153-1 , — 25-96 ), which... 

Medium acid baths, pH 4-5 At this acidity a dichromate solution plus sulphate ion as activator is sufficient to deposit chromate films in 30 min or so at room temperature or in a few minutes at boiling point. Unfortunately, a solution of alkali dichromate and alkali sulphate is quite unbuffered, and other substances must be added to give the bath a useful life over the working pH range. Acetates have been used successfully, but salts of aluminium, chromium, manganese and zinc have been more commonly employed. The pH of the solution rises slowly during use until basic chromates or sulphates begin to precipitate. The solution can then be rejuvenated by the addition of chromic or sulphuric acid or acid salts. 

Note in making up the chromic acid solution it is advisable to dissolve the silver nitrate separately and add it to the boiling chromic acid to prevent excessive crystallisation of the silver chromate. The chromic acid must be free from sulphate to avoid attack on the zinc. Immerse each specimen for 15 s in a 6% solution of hydriodic acid at room temperature to remove the remaining corrosion products. Immediately after immersion in the acid bath, wash the samples first in tap water and then in absolute methanol, and dry in air. This procedure removes a little of the zinc and a correction may be necessary. 

The early studies on the exchange system, carried out by Muxart et al., Menker and Garner, and Burgus and Kennedy, showed the exchange to be slow in sulphate , perchlorate, nitrate, and hydroxide media -. The isotopic method ( Cr) was used with separation of the Cr(III) and Cr(VI) being achieved by the precipitation of chromic oxide and lead chromate. Some evidence was obtained for the retardation of the exchange by hydrogen ions. 

The chromic acid oxidation of dithionic acid is independent of oxidant concentration and its rate is equal to that of the acid-catalysed hydrolysis to sulphite and sulphate, which must therefore constitute the rate-determining process . ... 

Electrochemical processes are particularly well suited for the manufacture of fine chemicals in view of their high sjjecificity (almost comparable to that offered by enzymes), the smaller number of steps required, adoption of milder conditions, lack of scale-up problems, avoidance of effluents, etc. The ease with which oxidation and/or reduction can be carried out with the practically mass-free clean electrons makes electrochemical processes well suited for such jobs, including paired synthesis in effect, we use electricity as a reagent . Consider a standard chemical oxidant like manganic or chromic sulphate. Here, a stoichiometric amount of the reduced salt will be formed the disposal of which can be a serious problem. If we adopt an electrochemical process, then the reduced salt is converted into the desired oxidized salt. 

Synonym(s) Chromic acid, lead and molybdenum salt lead chromate, sulphate and molybdate molybdenum-lead chromate molybdenum orange Lead dinitrate nitric acid lead(2+) salt lead (II) nitrate plumbous nitrate Lead(2+) oxide lead monoxide litharge massicot Lead(2+) phosphate Phosphoric acid lead(2+) salt ... 

In the same way ehloro-pentaquo-ehromic sulphate, [Cr(H20)5Cl]S04, is isomeric with sulphato-pentaquo-chromic chloride, [Cr(IT20)5S04]Cl. 

Salts such as hydroxo - triaquo - diammino - chromic sulphate, Cr(NH3)2(I-I20)s.OH]S04.H20, and the corresponding dipyridino-salt, Cr py 2(H20)3(0H)]S04, have been prepared, the former from dihydroxo-diaquo-diammino-chromie bromide by treatment with sulphuric acid,3... 

Nitro-pentammino-chromic Sulphate, [Cr(NH3)6N02]S04, is formed by rubbing the chloride with water and the calculated quantity of silver sulphate, filtering off silver chloride and precipitating the salt from the filtrate with alcohol. 

Chloro-pentammino-chromic Sulphate, [Cr(N I3)5Cl]S04.2H20, is prepared by treating the chloride with silver carbonate, removing the precipitated silver chloride and cautiously adding to the liquid dilute sulphuric acid a little silver chloride is thereby precipitated, it is removed by filtration, and the sulphate is precipitated from the filtrate by means of alcohol in carmine-red prisms. It is fairly soluble in water, and loses water if left over sulphuric acid or on heating to 100° C. 

Chloro - aquo - tetrammino - chromic Iodide, [Cr(NH3)4 (H20)C1]I2, is best prepared by decomposition of the sulphate with excess of barium iodide it is easily soluble in water and crystallises in red prisms. 

The sulphate, [Cr(NH3)4(H20)Br]S04, is also obtained from the bromide by decomposing it, in aqueous solution, with sodium sulphate and sulphuric acid. It is a red crystalline powder, easily soluble in water, and on heating the solution it decomposes into ammonia and chromic hydroxide. 

Dithiocyanato-tetrammino-chromic Thiocyanate, [Cr(NH3)4 (SCN)o]SCN, is prepared by warming an aqueous solution of ehloro-aquo-tetrammino chromic chloride, [Cr(NH3)4H2O.Cl]Cl2, with excess of potassium thiocyanate, when dark orange-red crystals separate. The crystals are soluble in water, and by the addition of concentrated hydrochloric or hydrobromic acid the corresponding chloride or bromide is produced. These also are orange-red in colour. The nitrate is formed from the chloride by precipitation with nitric acid, and the sulphate by rubbing the chloride with sulphuric acid.4... 

Dithiocyanato-diethylenediamino-chromic Chloride, [Cr en2 (SCN)2]C1.HC1, is prepared from the thiocyanate on treatment with concentrated hydrochloric acid, filtering off undissolved substance, and cooling the filtrate, when a crystalline powder separates. This is recrystallised from water and obtained in ruby-red glistening needles. From a solution of this salt may be precipitated the nitrate, sulphate, bromide, or dichromate by means of the corresponding acid or potassium dichromate. 

The corresponding pyridino-compound, [Cr py2(H20)(OH)3], is obtained by suspending dihydroxo-aquo-dipyridino-chromic sulphate, [Cr py2(0H)2(H20)2]2S04.12H20, in water and adding concentrated aqueous ammonia. The whole goes into solution, and then crystallises in pale violet leaflets which are insoluble in water and decompose on treatment with mineral acids.5... 

Octammino-diol-dichromic Salts, [Cr2(NH3)8(OH)2]R4.—These salts correspond to the ethylenediamine derivatives described above, and are prepared in the same manner. Dubsky, in an attempt to ascertain the constitution of the diol salts, prepared a number of salts belonging to the series. Octammino-diol-dichromic sulphate is formed when hydroxo-aquo-tetrammino-chromic sulphate is heated with excess... 

Hexaethylenediamino-hexol-tetrachromic Sulphate, [Cr4(OH)6en6](SO4)3.10H2O, is prepared from partially dehydrated chromic alum. The bluish-grey powder obtained is heated with ethylene-diamine monohydrate on a water-bath till a red-coloured mass is produced, which consists of a mixture of potassium sulphate, luteo-chromic sulphate, and the sulphate of the hexol compound, and from the mixture the latter compound is obtained by dissolving out the more soluble salts with water. The crude, difficultly soluble sulphate is purified by dissolving in dilute sulphuric acid and reprecipitating with excess of ammonia. It crystallises in small needles which are almost insoluble in water and soluble in dilute acids. 

The electrical conductivities of soln. of a great many compounds in liquid hydrogen halides have been measured by E. H. Archibald and D. McIntosh. The conductivity is raised considerably by phosphoryl chloride. Sodium sodium sulphide, borate, phosphate, nitrate, thiosulphate, and arsenate chromic anhydride potassium nitrate, hydroxide, chromate, sulphide, bisulphate, and ferro- and ferri- cyanide ammonium fluoride and carbonate j rubidium and caesium chloride magnesium sulphate calcium fluoride ... 

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