Sulphate copper

Lallemant et al. [601] measured rates of dehydration of both CuS04 5 H O and CuS04 3 HaO and concurrently identified the phases present 

Ng et al. [1261] report that dehydration of copper sulphate pentahydrate (- CuS04 3 H20) 320—336 K, obeys the Avrami—Erofe ev equation [eqn. (6), n = 2] with E = 104 kj mole-1. Dehydration of the trihydrate (- CuS04 H20), 343.5—359 K, obeyed the same rate expression with E = 134 kJ mole 1. Activation energies are approximately equal to reaction enthalpies. 

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Fehling s solution A solution of copper sulphate, sodium potassium tartrate and NaOH used for estimating and detecting reducing sugars. 

If a metal, such as copper, is placed in contact with a solution containing the ions of that metal, such as from aqueous copper sulphate, then we expect an equilibrium to be set up of the following fonn ... 

Metallic Derivatives, (a) Cuprous Acetylide. CujCg. Prepare an ammoniacal solution of cuprous chloride by first adding dilute ammonia to 2-3 ml. of dilute copper sulphate solution until the initial precipitate just redissolves and a clear deep-blue solution is obtained now add an aqueous solution of hydroxylamine hydrochloride drop by drop with shaking until the solution becomes first green and then completely colourless, the cupric salt being thus reduced to the cuprous derivative. 

Required Copper sulphate, 28 g. sodium chloride, 9-5 g. sodium bisulphite, 14 g. hydrochloric acid, 70 ml. aniline, 20 ml. sodium nitrite, 17 g. 

Potassium cupro-cyanide is the most convenient form in which cuprous cyanide can be used in Sandmeyer s Reaction. It is prepared by adding an excess of potassium cyanide to copper sulphate solution, whereby the cupric cyanide which is formed immediately breaks down to give cuprous cyanide and cyanogen, and the cuprous cyanide then dissolves in the excess of potassium... 

Then, while the diazonium solution is standing in ice-water, dissolve 55 g. of powdered copper sulphate (CuS04,5Ha0) in 200 ml. of water contained in a 1500 ml. flat-bottomed flask, for which a steam-distillation fitting is available for subsequent use. Place a thermometer in the copper sulphate solution and warm the latter to 60-65 . Now cautiously add a solution of 60 g. of powdered potassium cyanide in too ml. of water to the copper... 

Required Anthranilic acid, 20 g. anhydrous sodium carbonate, 7 5 g, sodium nitrite, 12 g. concentrated hydrochloric acid, 190 ml. crystalline copper sulphate, 50 g. concentrated ammonia, 85 ml, hydroxylamine hydrochloride, 14-5 g. (or hydroxylamine sulphate, 17-4 g.) acetic acid, 10-20 ml,... 

B) Preparation of the Cuprous Solution, Add 85 ml. of concentrated ammonia solution (d, o-o88) to a solution of 50 g. of crystalline copper sulphate in 200 ml. of water, and cool to 10 . Dissolve 14 5 g. of hydroxylamine hydrochloride (or 17-4 g. of the sulphate) in 50 ml. of water, cool to 10 , and add a solution of 9 g. of sodium hydroxide in 30 ml. of water. Without delay add this hydroxylamine solution with stirring to the copper solution, which will be immediately reduced, but will retain a blue colour. 

Arylarsonic acids are most readily prepared by the Bart Reaction, in which a diazonium salt in aqueous solution is run into a solution of sodium arsenite in an excess of sodium carbonate. The addition of copper sulphate to the +. ... 

Required Arsenious oxide, 27 g. aniline, 20 ml. (20 g.) anhydrous sodium carbonate, 55 g. crystalline copper sulphate,... 

Add in turn 55 g. of anhydrous sodium carbonate, 27 g. of powdered arsenious oxide and i g. of hydrated copper sulphate to 175 ml. of water in a 2 litre beaker, and heat the stirred mixture until an almost clear solution is obtained then immerse the stirred solution in ice-water, and cool it to 5°. 

It does not reduce Fehling s solution, but turns it a pale green colour. (Note that salicylaldehyde turns ordinary copper sulphate solution a pale green.)... 

NH2CONH2 = NH2CONHCONH2 + NH3 Dissolve the solid residue in a few ml. of warm 10% NaOH solution, cool and add i drop of very dilute copper sulphate solution. A purple coloration is obtained. ... 

A purple or rose pink coloration i produced when sodium hydroxide and dilute copper sulphate solution are added to compounds containing two -CONH- groups attached either to one another, or to the same nitrogen atom, or to the same carbon atom. It is therefore also given by oxamide, NHjCO CONH, malonamide, NHtCO-CH, CONH, and by proteins and peptides. In fact the -COKH - is often spoken of as the peptide linkage. 

Prepare the cupric hydroxide by dissolving 2 g. of copper sulphate in about too ml. of water, and adding with stirring 16 ml. of N.NaOH solution. Filter off the precipitate and wash thoroughly with water. 

Solution A. Dissolve 17 320 g. of powdered crystalline copper sulphate, CuS04,5H20, in water and make the solution up to 250 ml. in a graduated flask. 

To appreciate the action of a drying agent of class (a), let us imagine some anhydrous copper sulphate in an evacuated vessel provided with a pressure gauge, and water is allowed to enter slowly the temperature is assumed constant at 25°. The results may be best expressed by means of a vapour pressure - composition diagram (Fig. 7, 20, 1). The initial system is represented by the point A the pressure will rise along AB until the monohydrate CuS04,H20 commences to form at B. 

We may now understand the nature of the change which occurs when an anhydrous salt, say copper sulphate, is shaken with a wet organic solvent, such as benzene, at about 25°. The water will first combine to form the monohydrate in accordance with equation (i), and, provided suflScient anhydrous copper sulphate is employed, the effective concentration of water in the solvent is reduced to a value equivalent to about 1 mm. of ordinary water vapour. The complete removal of water is impossible indeed, the equilibrium vapour pressures of the least hydrated tem may be taken as a rough measure of the relative efficiencies of such drying agents. If the water present is more than sufficient to convert the anhydrous copper sulphate into the monohydrate, then reaction (i) will be followed by reaction (ii), i.e., the trihydrate will be formed the water vapour then remaining will be equivalent to about 6 mm. of ordinary water vapour. Thus the monohydrate is far less effective than the anhydrous compound for the removal of water. 

Cuprous chloride. Hydrated copper sulphate (125 g.) and sodium chloride (32-5 g.) are dissolved in water (400 ml.) boiling may be necessary. An allialine solution of sodium sulphite (from 26 5 g. of sodium bisulphite and 17 -5 g. of sodium hydroxide in 200 ml. of water) or the solution of the sodium bisulphite alone is added to the resulting hot solution during about 5 minutes with constant shaking. The solution will be decolourised or nearly so. It is then cooled to room temperature (or in an ice bath), and the supernatant liquid is decanted... 

Cuprous bromide. The solid salt may be prepared by dissolving 150 g. of copper sulphate crystals and 87 5 g. of sodium bromide dihydrate in 500 ml. of warm water, and then adding 38 g. of powdered sodium sulphite over a period of 5-10 minutes to the stirred solution. If the blue colour is not completely discharged, a little more sodium sulphite should be added. The mixture is then cooled, the precipitate is collected in a Buchner funnel, washed twice with water containing a little dissolved sulphurous acid, pressed with a glass stopper to remove most of the liquid, and then dried in an evaporating dish or in an air oven at 100 120°. The yield is about 80 g. 

A solution of cuprous bromide may be prepared either by dissolving the solid in hot constant boiling point hydrobromic acid or by refluxing a mixture of 63 g. of crystallised copper sulphate, 20 g. of copper turnings, 154 g. of sodium bromide dihydrate, 30 g. (16-3 ml.) of concentrated sulphuric acid and 1 litre of water for 3-4 hours. If the colour of the solution has not become yellowish after this period of heating, a few grams of sodium sulphite should be added to complete the reduction. 

Cuprous cyanide solution. The most satisfactory method is to dissolve the cuprous cyanide (1 mol) in a solution of technical sodium cyanide (2 5-2-6 mols in 600 ml. of water). If it is desired to avoid the preparation of solid cuprous cyanide, the following procedure may be adopted. Cuprous chloride, prepared from 125 g. of copper sulphate crystals as described under 1 above, is suspended in 200 ml. of water contained in a 1-litre round-bottomed flask, which is fitted with a mechanical stirrer. A solution of 65 g. of technical sodium cyanide (96-98 per cent.) in 100 ml. of water is added and the mixture is stirred. The cuprous chloride passes into solution with considerable evolution of heat. As the cuprous cyanide is usually emplo3 ed in some modification of the diazo reaction, it is usual to cool the resulting solution in ice. 

Dissolve 3 g. of copper sulphate pentahydrate and 1 g. of sodium chloride in 12 ml. of hot water, and add a solution of 1 g. of sodium bisulphite in 10 ml. of 5 per cent, sodium hydroxide solution. Shake, cool under the tap, and wash the precipitated wlute cuprous chloride with water by decantation. Dissolve the cuprous chloride in a few ml. of concentrated ammonia solution and dilute with water to 10 ml. 

Preparation of Fehling s solution. Solution No. 1. Dissolve 34-64 g. of A.R. copper sulphate crystals in water containing a few drops of dilute sulphuric acid, and dilute the solution to 500 ml. 

The latter may be identified by dissolving the residue in 5 ml. of water and adding 1 op of very dilute copper sulphate solution and 2 drops of 10 per cent, sodium hydroxide solution a violet colour is produced. 

Benedict s solution Is prepared as follows. Dissolve 86-5 g. of crystallised sodium citrate (2Na,C,H(0, l 1H,0) and 50 g. of anhydrous sodium carbonate in about 350 ml. of water. Filter, if necessary. Add a solution of 8-65 g. of crystallised copper Sulphate in 50 ml. of water with constant stirring. Dilute to 500 ml. The resulting solution should be perfectly clear if it is not, pour it through a fluted filter paper. 

Phenylarsonic acid may be obtained from the reaction between phenyl-diazonium chloride and sodium arsenite in the presence of a trace of copper sulphate ... 

In a 1 5 or 2-Utre rovmd-bottomed flask, prepare cuprous chloride from 105 g. of crystallised copper sulphate as detailed in Section 11,50,1. Either wash the precipitate once by decantation or filter it at the pump and wash it with water containing a httle sulphurous acid dissolve it in 170 ml. of concentrated hydrochloric acid. Stopper the flask loosely (to prevent oxidation) and cool it in an ice - salt mixture whilst the diazo-tisation is being carried out. 

Chlorobenzene. Prepare a solution of phenyldiazonium chloride from 31 g. (30 -5 ml.) of aniUne, 85 ml. of concentrated hydrochloric acid, 85 ml, of water, and a solution of 24 g. of sodium nitrite in 50 ml. of water (for experimental details, see Section IV,60). Prepare cuprous chloride from 105 g. of crystallised copper sulphate (Section 11,50,1), and dissolve it in 170 ml. of concentrated hydrochloric acid. Add the cold phenyl diazonium chloride solution with shaking or stirring to the cold cuprous chloride solution allow the mixture to warm up to room temperature. Follow the experimental details given above for p-chlorotoluene. Wash the chlorobenzene separated from the steam distillate with 40 ml. of 10 per cent, sodium hydroxide solution (to remove phenol), then with water, dry with anhydrous calcium chloride or magnesium sulphate, and distil. Collect the chlorobenzene (a colourless liquid) at 131-133° (mainly 133°), The yield is 29 g. 

Method 2. Prepare 40 g." of cuprous bromide according to Section 11,50,2 (about 75 g. of crystaUised copper sulphate are required) and dissolve it in 40 ml. of constant boihng point hydrobromic acid (48% HBr) contained in a 2 - 5 Utre rovmd-bottomed flask. 

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