Crystallization Cuprous oxide

Calcium carbonate has normal pH and inverse temperature solubilities. Hence, such deposits readily form as pH and water temperature rise. Copper carbonate can form beneath deposit accumulations, producing a friable bluish-white corrosion product (Fig. 4.17). Beneath the carbonate, sparkling, ruby-red cuprous oxide crystals will often be found on copper alloys (Fig. 4.18). The cuprous oxide is friable, as these crystals are small and do not readily cling to one another or other surfaces (Fig. 4.19). If chloride concentrations are high, a white copper chloride corrosion product may be present beneath the cuprous oxide layer. However, experience shows that copper chloride accumulation is usually slight relative to other corrosion product masses in most natural waters. 

Figure 4.18 As in Fig. 4.17 but with carbonate mound removed to reveal sparkling lavender cuprous oxide crystals. 

Figure 4.19 Scanning electron microscope picture of cuprous oxide crystals as shown in Fig. 4.18. Note the partial octahedral symmetry.

Figure 4.25 As in Figs. 4.23 and 4.24. Corrosion product mound broken open to reveal sparkling cuprous oxide crystals.

Internal surfaces of all tubes were severely attacked (Fig. 4.29). A brown deposit layer consisting of magnetite, iron oxide hydroxide, and silica covered all surfaces. Deposition was thicker and more tenacious along the bottom of tubes. These deposits had a distinct greenish-blue cast caused by copper corrosion products beneath the deposit. Underlying corrosion products were ruby-red cuprous oxide crystals (Fig. 4.29). Areas not covered with deposits suffered only superficial attack, but below deposits wastage was severe. 

A few months later, a second set of tubes was submitted for examination. These tubes had not been cleaned. Close examination revealed arrowhead-shaped mounds of fibrous debris lodged on the tube wall (Fig. 11.20). Dislodgement of these mounds revealed an arrowheadshaped region of shallow corrosion containing sparkling crystals of cuprous oxide, essentially identical to that described above. 

Cuprous Oxide, Cu-O, red cubic crystals, insoluble in H 0 soluble in HCI. NHjOH. or ammonium chloride. Cuprite, a copper ore. is of this composition. Refined compound is used in electrical rectifiers. 

CUPRITE. The mineral cuprite, cuprous oxide. Cu 0. occurs as isometric crystals, usually octahedrons, hut may he cubes, dodecahedrons or modified combinations, it also is found as a massive, earthy material. Its fracture is conchoidal to uneven brittle hardness,, 1.5-4 specific gravity, 6.14 luster, submetallic to earthy color, red nearly transparent to nearly opaque. Its streak is shining brownish-red. Cuprite is a secondary mineral resulting doubtless from the oxidation of copper sulfides. It is often found associated with native copper, malachite and azurile. 

B. C. Dutt and S. N. Sen found that when nitric oxide is passed into a suspension of barium dioxide in water, barium nitrite, not nitrate, is formed. P. Sabatier and J. B. Senderens observed no change when nitric oxide is passed over Cuprous Oxide at 500°. H. A. Auden and G. J. Fowler observed that dry nitric oxide and Silver oxide, at ordinary temp., form silver and silver nitrate P. Sabatier and J. B. Senderens also obtained silver and silver nitrite by passing nitric oxide into water with silver oxide in suspension. C. F. Schonbein found gold oxide is reduced by moist nitric oxide, forming nitrous acid. P. Sabatier and J. B. Senderens found that titanium sesquioxide forms white titanic oxide when heated in an atm. of nitric oxide and that stannous oxide below 500° burns in an atm. of nitric oxide, forming stannic oxide. If nitric oxide be passed into water with lead dioxide in suspension, the water is coloured, and in about 3 hrs., lead nitrite and nitrate are formed, and later, rhombic crystals of a basic nitrite. B. C. Dutt and S. N. Sen said that the nitrate is formed by the action of the dioxide on the nitrite. Lead dioxide is reduced to lead oxide by nitric oxide at 315°, and H. A. Auden and G. J. Fowler found that the reaction begins at 15°, when a basic lead nitrite is... 

No. DRP 637,318, 128.10 grams of 5,5-dimethylhydantoin described in Beil., Vol. 24, 289 and 198.53 grams of cuprous oxide. The mixture was heated to 200°C for 24 hours, then cooled to 20°C and filtered. The residue was rinsed with phenyl oxide, then extracted with ethyl acetate. The ethyl acetate phase was concentrated to dryness under reduced pressure at 60°C and the residue was taken up in ammoniacal dichloroethane. The crystals obtained were dried at 60°C to obtain 66.55 grams of crude product which, after purification from aqueous ethanol yielded 62.55 grams of purified desired product. 

Because of the importance of cuprous oxide and cuprous-based systems in catalysis, the most common shape of the microcrystals of CU2O, as determined experimentally and theoretically, is reported in Fig. 1. Several investigations of Cu20 single crystals have been reported, and these are particularly valuable for purposes of this review. 

Fig. 25. Adsorption of nitrogen on single crystal cubic copper and cuprous oxide. [After Rhodin, J. Am. Chem. Soc. 72, 4343 (1950).]...

Some experimental data obtained in high temperature oxidation studies indicate that the above might be a fruitful field of investigation. Harris et al (72) have shown that the nucleation and growth of cuprous oxide on copper are closely related to dislocations in the metal. Gulbransen and Andrews (73) report data which indicate that the growth of oxide nuclei on iron is related to the number and arrangement of dislocations in the metal crystal. 

Pig. 3. A stereographic plot of cuprous oxide orientation regions on a copper single crystal. 1. Regions cross-hatched with vertical and horizontal lines Oxide completely parallel to metal. One orientation. 2. dear regions Anti-parallel orientation, (Ili)Cu20//(lll)... 

Fio. 2. Diagrammatic representation of a cross section through the (001) plane at the surface of a cuprous oxide crystal. Key O Oxygen atoms Copper atoms — — Protruding oxide surface . Buried oxide surface. 

In llraidy s modification, which is stated to give more consistent results, 2 5 g. of very finely divided air-dry cotton is treated with a mixture of 5 c.c. of 10 per cent, copper sulphate (cryst.) and 95 c.c. of an almost saturatcd solution of sodium carbonate and bicarbonate g crystals and 50 g. bicarbonate made up to 1 litre). The cotton is immersed by means of a rod and the air bubbles are allowed to escape the flask is then surrounded with boiling water for exactly three hours. The contents arc filtered off on an asbestos filter and washed first with dilute sodium carbonate solution and then with water. Then the residual cuprous oxide is dissolved by treatment with a solution containing 100 g. of iron alum and 140 g. of concentrated sulphuric acid per litre. Two such treatments usually suffice. The fitter is tben washed with 2 Af-sulphuric acid the combined filtrate and washings arc titrated with A /25 potassium permanganate solution. According to Brissaud the test is affected by air. 

HjCuOj, mol wt 122.58. C 19.59%, H 2.47%, Cu 51.83%, O 26.10%, CHjCOOCu, Obtained as a sublimate by heating cupric acetate in vacuo to temps above 220" Angel, Har-oourt, J. Chem. Soc. 81, 1385 (1902) prepn from cuprous oxide and acetic acid -acetic anhydride Shimizu, Weller, J-Am. Chem. Soc. 74, 4469 (1952). Crystal structure T. 

Cuprous Oxide. Red copper oxide C.I. 77402 Perenex Yellow Cuprocide Copper-Sandoz Caocobre. CujO mol wt 143.08. Cu 88.82%, O 11.18%. Occurs in nature as the mineral cuprite (red to reddisli-brown octahedral or cubic crystals). Prepd commercially by furnace reduction of mixtures ot copper oxides with Cu Drapeau, Johnson, U.S. pats. 2,758,014 2,891,842 (1956, 1959 to Glidden) by decompn of copper ammonium carbonate Rowe, U.S. pat. 2,474,497 Klein, U.S. pat. 2.474,533 (both 1949 to Lake Chemical) Rowe, U.S. pat. 2,536,096, Munn, U.S. pat. 2,670,273 (1951, 1954 to Mountain Copper) by treatment of Cu(OH)j with S02 Rowe, U pat. 2,665,192 (1954 to Mountain Chemical) or by electrolysis of an aq soln of NaCI between Cu electrodes Arend, Paint Technology 13, 265 (1948). Laboratory prepns Glemser, Seuer in Handbook of Preparative Inorganic Chemistry, vol. 2, G. 

Possibly, the competition between the diffusion mechanism and the aggregation mechanism occurred in this case, i.e., at high dose rate, the aggregation mechanism overwhelms the diffusion mechanism, so cuprous oxide forms mainly polycrystals in contrast, when the dose rate becomes lower, the cuprous oxide single crystals are formed. 

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