Cupric sulphate

Anhydrous cupric sulphate is white but forms a blue hydrate and a blue aqueous solution. The solution turns yellow when treated with concentrated hydrochloric acid, dark blue with ammonia, and gives a white precipitate and brown solution when treated with potassium iodide. A yellow-brown aqueous solution of ferric chloride becomes paler on acidification with sulphuric or nitric... 

The special reducing agent (a solution containing cupro-ammonia ions) is first prepared. Dissolve 63 g. of crystallised copper sulphate in 250 ml. of water in a 1-Utre heaker, add 100 ml. of concentrated ammonium hydroxide solution (sp. gr. 0-88), and cool the solution to 10°. Dissolve 17 8 g. of hydroxylammonium chloride or 21 g. of hydroxylammonium sulphate in 60 ml. of water, cool to 10°, and add 42 -5 ml. of QN sodium hydroxide solution if the resulting solution of tydroxylamine is not clear, filter it at the pump. Without delay add the hydroxylamine solution, with stirring, to the ammoniacal cupric sulphate solution. Reduction occurs at once, a gas is evolved, and the solution assumes a pale blue colour. Protect the reducing agent from the air if it is not used immediately. 

K has the value of about 1 x 10 at 298 K, and in solutions of copper ions in equilibrium with metallic copper, cupric ions therefore greatly predominate (except in very dilute solutions) over cuprous ions. Cupric ions are therefore normally stable and become unstable only when the cuprous ion concentration is very low. A very low concentration of cuprous ions may be produced, in the presence of a suitable anion, by the formation of either an insoluble cuprous salt or a very stable complex cuprous ion. Cuprous salts can therefore exist in contact with water only if they are very sparingly soluble (e.g. cuprous chloride) or are combined in a complex, e.g. [Cu(CN)2) , Cu(NH3)2l. Cuprous sulphate can be prepared in non-aqueous conditions, but because it is not sparingly soluble in water it is immediately decomposed by water to copper and cupric sulphate. 

Oxidation by aqueous cupric sulphate occurs slowly enough to be studied by conventional means at 25 °C giving a rate law ... 

In chemically-cured materials, one example of an initiator/activator system is hydrogen peroxide as initiator, ascorbic acid as activator and cupric sulphate as co-activator. In light-cured materials, camphorquinone is used as a visible-light photochemical initiator, sodium p-toluene-sulphinate as activator and ethyl 4-dimethylaminobenzoate as photoaccelerator. 

Cholecalciferol (vitamin D-3) differs from calciferol only in the alkyl side-chain, so it was assumed to be in the twisted conformation (75a). In alcoholic solution, vitamin D-3 was irradiated with a mercury arc lamp through a cupric sulphate solution filter to give wavelengths above 250 nm. Six products were isolated. Conformation (75a) could reasonably give rise to the assigned structures (76a), (77a) and (78a) (Scheme 2.3). Photoisomerization could give conformation (75b), which would explain the isolation of (76b), (77b) and (78b). The report is confident on four of the new compounds, but notes that the cyclobutene structures (78a) and (78b) are tentatively assigned [63]. 

In iodometry, an equivalent amount of iodine is liberated when the given sample of an oxidizing agent oxidizes potassium iodide in an acidic medium, for example the determination of cupric sulphate (CuS04) ... 

Copper tungstate Cupric sulphate 5.0 g l-1, sodium tungstate 2.5 g l-1... 

The electrochemical mechanism of cupric sulphate activating sphalerite has been studied. The measured cyclic voltammogram curves in aqueous solution at different pH with sphalerite compound electrode are shown as solid lines in Fig. 6.1. 

Copper-selenium catalyst tablets - each tablet contains 0.5 g of cupric sulphate pentahydrate, and 0.02 g of selenium. 

When passed through a solution of cupric sulphate, it causes a black precipitate of cupric phosphide —... 

Cupric sulphate unites with ammonia, forming the compound Cu(N[Ia).1SO,1. The co-ordination number is again four, and the formula is... 

The valency of the complex radicle is the same as that of the central metallic atom when the complex contains only ammonia, substituted ammonia, water, or other neutral group. For example, cobalt in eobaltie. salts is trivalent, and the cobalt complex with ammonia, Co(NI13)8 ", is likewise trivalent copper in cupric sulphate is divalent, and the copper complex, [Cu(NH3)4] , is also divalent. In the same wn.y [Co(NH3)5.H30] " and [Co(NII3)4.(II20)2] " are trivalent, as also [Co(NH3)2.en2]" and [Co.en3] ", where en represents cthyleucdiamine, CH NH2... 

By the action of ammonia on cuprous or on cupric salts, substances are formed containing varying amounts of ammonia. Cuprous ammines arc colourless, unstable, and readily turn blue, passing into the more stable cupric ammines. The cupric ammines are deep blue in colour and dissolve in water, yielding dark blue solutions. In the dry state many of them arc stable. The most important ammines of copper are those of the salts, cupric chloride and cupric sulphate. 

Ammino-derivatives of Cupric Sulphate.—Cupric sulphate forms with ammonia four ammino derivatives, namely, pentammino-cupric sulphate, [Cu(NII3)5]S04 tetrammino-cupric sulphate, [Cu(NH3)4]S04 diammino-cupric sulphate, [Cu(NH3)2]S04 and monammino-cuprzc sulphate, [Cu(NH3)]S04. The tetrammino salt is the best known and the one most easily obtained. It exists both in the anhydrous and in the hydrated state. 

Monohydrated Tetrammino-cupric Sulphate, [Cu(NH3)4]S04. HaO.—The compound was first described by Stisser in 1693 and later analysed by Berzelius, who proved it to contain four molecules of ammonia and one molecule of water. It is formed by treating an aqueous solution of cupric sulphate with excess of ammonium hydroxide and precipitating the deep blue compound by the addition of alcohol. The same derivative may be obtained by passing ammonia gas into an aqueous solution of cupric sulphate, when, as the ammonia concentration 1 Dawson, Trans. Chem. 3oc., 1906, 89, 1666. 

Anhydrous Tetrammino-cupric Sulphate, [Cu(NIT3)j]S04.— The anhydrous tetrammino salt is prepared by passing ammonia gas over dehydrated cupric sulphate at a temperature between 90° and 150° C.,5 or by keeping pentammino-cupric sulphate in a desiccator over sulphuric aeid. 

Pentammino-cupric Sulphate, [Cu(NII3)5]S04.—Anhydrous cupric sulphate is insoluble in liquid ammonia, but both anhydrous and hydrated salt absorb ammonia gas. At first the reaction is vigorous, the white anhydrous salt becomes blue and then absorption of ammonia gradually slows down the product formed is assumed to be the pent-ammino-sulphatc. 

Pcntammino-eupric sulphate is prepared by allowing carefully dried ammonia gas to act upon cooled, dry cupric sulphate.7 The product is stable if kept over sulphuric acid, but is decomposed by moist... 

Pentammino-cuprie sulphate melts below 200° C., darkens in colour, and at 400° C. completely decomposes, leaving1 a residue of metallic copper. It is stable up to 99° C., and when heated between 99° and 141° C. loses one molecule of ammonia and passes into tetrammino-cupric sulphate.1... 

Diammino-cupric Sulphate, [Cu(NH3)2]S04, is formed when tetrammino-cupric sulphate is heated above 150° C. It is an apple-green powder, which absorbs moisture from the air and becomes blue in colour. 

Hydroxylamine Derivatives.—Several derivatives of cupric sulphate containing hydroxylamine in place of ammonia are known. Thus, cupric sulphate unites with hydroxylamine, giving a mono-hydroxylamino-compound Cu[NH20H]S04, a dihydroxylamino-salt, [Cu(NH20H)2]S04, and a pentahydroxylamino-salt, [Cu(NH2OIT) ]SO.j. The latter is unstable, but the two former compounds are stable in the dry state and even in solution up to 0° C. Above that temperature reduction of the salts occurs. 

The hydrated nail is obtained by passing a weak electric current through a strongly ammoniacal solution of cupric sulphate.4 It forms colourless needle-shaped crystals and behaves like the anhydrous form. 

Anhj drous cupric chloride, like anhydrous cupric sulphate, absorbs ammonia rapidly the absorption is accompanied by increase in bulk, and the brown chloride changes to a blue powder having the composition CuCl2.6NtI3. The following compounds of cupric chloride with ammonia are known —... 

Tetrammino-cupric Iodide is produced by adding potassium-iodide solution to an aqueous ammoniacal solution of cupric sulphate and then saturating the mixture with ammonia gas at 0° C.3... 

The cuprous salt. [Cr(NH3)2(SCN)4]Cu, is precipitated from the ammonium salt by the addition of cupric sulphate and sulphur dioxide as a yellow powder. 

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