Cupric sulphate pentahydrate

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

Diazotise 223 g. of 2-naphtliylamine-l-sulphonic acid as detailed under fi-Bromonaphthalene in Section IV,62. Prepare cuprous cyanide from 125 g. of cupric sulphate pentahydrate (Section IV,66) and dissolve it in a solution of 65 g. of potassium cyanide in 500 ml. of water contained in a 1-litre three-necked flask. Cool the potassium cuprocyanide solution in ice, stir mechanically, and add the damp cake of the diazonium compound in small portions whilst maintaining the temperature at 5-8°. Nitrogen is soon evolved and a red precipitate forms gradually. Continue the stirring for about 10 hours in the cold, heat slowly to the boiling point, add 250 g. of potassium chloride, stir, and allow to stand. Collect the orange crystals which separate by suction filtration recrystallise first from water and then from alcohol dry at 100°. The product is almost pure potassium 2-cyanonaphthalene-l-sulphonate. Transfer the product to a 2-litre round-bottomed flask, add a solution prepared from 400 ml. of concentrated sulphuric acid and 400 g. of crushed ice, and heat the mixture under reflux for 12 hours. Collect the -naphthoic acid formed (some of which sublimes from the reaction mixture) by suction filtration... 

Standard copper solution 1 mg/ml. Dissolve 3.9280 g of cupric sulphate pentahydrate, CUSO4.5H2O, in water containing 1 ml of concentrated H2SO4, and dilute the solution with water to 1 litre. 

Fig. 12.18. The bond structure in cupric sulphate pentahydrate, Cu(H20)4S04.H20. For the interpretation of this diagram see the legend of fig. 12.17.

Diazotise 223 g. of 2-naphtliylamine-l-sulphonio acid as detailed under -Bromonaphlhalene in Section IV,62. Prepare cuprous cyanide from 125 g. of cupric sulphate pentahydrate (Section IV,66) and dissolve it in a solution of 65 g. of potassium cyanide in 500 ml. of water contained in a... 

Dissolve 0.375 g of analytical reagent quality cupric sulphate pentahydrate, CuS04 5H20, in 1000 ml of distilled water. The solution is stable indefinitely. 

The remainder of Richards s work on copper by chemical methods concerned the composition of cupric oxide and cupric sulphate, and was undertaken principally with the object of investigating the nature and magnitude of the errors of earlier workers. Cupric oxide prepared from the nitrate by ignition was found to contain occluded gases, mainly nitrogen. The impossibility of avoiding partial decomposition in the preparation of cupric sulphate free from water by dehydration of the pentahydrate was also demonstrated. At 260° C. the salt retains more than 0-1 per cent, of water, and at 400° C. 0-042 per cent. These errors vitiated the results of most of the early workers on the atomic weight of copper, and explain the low values found by Hampe. 

Cupric pyrophosphate, Cu2P207.—The anhydrous salt is precipitated as a greenish-white powder by addition of sodium pyrophosphate to a solution of a cupric salt.8 The pentahydrate crystallizes from a solution containing cupric sulphate and sodium metaphosphate.9... 

Cupric metantimonate, Cu(Sb03)2,5H20.—The pentahydrate is obtained as a bluish-green precipitate by addition of potassium metantimonate to a solution of cupric sulphate.9... 

CUSO4. 3 H2O. Cupric sulphate forms hydrates with 1, 3, and 5 H2O. In contrast to the pentahydrate, in which only 4 H2O are associated with the cations, all the water is coordinated to Cu in the trihydrate. The coordination group around the metal ion consists of 3 H2O + 1 0 (mean Cu—0, 1-94 A) with two more distant 0 atoms of SO4 ions (at 2-42 A) completing a distorted octahedral group. 

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