Cupric ferrocyanide

Ferrocyan-kaUum, n. potassium ferrocyanide. -kupfer, n. cupric ferrocyanide. -natrium, n. sodium ferrocyanide. -silber, n. silver ferrocyanide. -verbindung, /. ferrocyanide. -wasserstoff, m., -wasserstoffsMure, /. ferro-cyanic acid, -zink, n. zinc ferrocyanide. -zinn, n. tin ferrocyanide. 

J. Wang and A.S. Arribas, Biocatalytically induced formation of cupric ferrocyanide nanoparticles and their application for electrochemical and optical biosensing of glucose. Small 2, 129 (2006). 

Fluorination with fluorine produces copper(ll) fluoride, CuF2. Adding potassium ferrocyanide to CuCb aqueous solution precipitates out reddish brown cupric ferrocyanide. Reaction with caustic soda forms blue cupric... 

Cupric ferrocyanide, also known as copper(II) hexacyanoferrate(II) or cop-per(ll) hexakis(cyanoferrate(3-)) Cu2Fe(CN)6, is obtained as a chocolate-brown precipitate by the addition of a copperfll) salt solution to ferrocyanide ... 

The applications of cupric ferrocyanide are very limited. It is used as a chemical membrane for osmosis. 

In qualitative analysis copper is detected by precipitation as cupric sulphide from hydrochloric-acid solutions of its salts. To prevent the formation of a colloidal precipitate, the solution should be hot, and should contain excess of the acid. The sulphide is soluble in hot, dilute nitric acid, and in potassium-cyanide solution, but almost insoluble in solutions of alkali-metal sulphides. It dissolves to some extent in ammonium-sulphide solution. Other aids in the detection of copper are the blue colour of solutions of cupric-ammonia salts the reddish-brown precipitate of cupric ferrocyanide, produced by addition of potassium ferro-cyanide to cupric solutions the formation of an intense purple coloration by the interaction of hydrogen bromide and cupric salts, a very delicate reaction2 the formation of a bluish-green borax bead and the ready isolation of the metal from its compounds by the action of reducers. 

Sodium cupriferrocyanide, Na2CuFe(CN)6, is prepared by boiling solutions of cupric salts and sodium ferrocyanide, and by boiling cupric ferrocyanide with sodium ferrocyanide and, after filtering, allowing the clear solution to evaporate in air.1 It yields lustrous brown crystals, insoluble in cold water, but decomposed when boiled with water, dilute acids, or alkalies. 

Arribas, A.S., Vazquez, T., Wang, J., Mulchandani, A., Chen, W. (2005). Electrochemical and optical bioassay of nerve agents based on the organophosphorous-hydrolase mediated growth of cupric ferrocyanide nanoparticles. Electrochem. Commun. 7 1371-4. 

A semipermeable membrane is a membrane with very small holes in it, of such a size that molecules of the solvent are able to pass through but molecules of the solute are not. A useful semipermeable membrane for measurement of osmotic pressure is made by precipitating cupric ferrocyanide, Cu2Fe(CN)g, in the pores of an unglazed porcelain cup, which gives the membrane mechanical support to enable it to withstand high pressures. Accurate measurements have been made in this way to over 250 atm. Cellophane membranes may also be used, if the osmotic pressure is not large (Fig. 16-8). 

Cupric ferrocyanide Cu2Fe(CN)0.7K2O Ferrocyanide of copper prusslate of copper. 

Cupric ferrocyanide, Cu2Pe(CN)e, is sufficiently characteristic in appearance to be serviceable in testing for cupric salts. 

It forms soft, flexible, lemon-yellow crystals, permanent in air at ordinary temperatures. They begin to lose Aq at 60° (140° F.), and become anhydrous at 100° (213° F.). Soluble in HaO insoluble in alcohol, which precipitates it from its aqueous solution. When calcined with KHO or KaCOs, potassium cyanid and cyanate are formed, and Fe is precipitated. Heated with dilute HaSOi, it yields an insoluble white or blue salt, potassium sulfate, and hydrocyanic acid. Its solutions form with those of many of the metallic salts insoluble ferrocyanids those of Zn, Pb, and Ag are white, cupric ferrocyanid is mahogany-colored, fer-... 

Characters and Tests.—Blue crystalline salt, in oblique prisms, soluble in water, forming a pale blue solution which strongly reddens blue litmus. The aqueous solution gives with barium chloride a white precipitate (barium sulphate), insoluble in hydrochloric acid, showing the salt to be a sid-phate and with potassium ferrocyanide a maroon-red precipitate, indicating the presence of copper (cupric ferrocyanide). If an aqueous solution of the salt be mixed with twice its volume of chlorine water, to peroxidize any iron that may be present, and solution of ammonia be added, the precipitate (cupric hydrate) formed by the first addition of the ammonia will be dissolved by a further and sufficient addition of the alkali, and a violet blue solution (copper ammonio-sulphate) will be produced, leaving nothing un ssolved unless iron be present, in which case a reddish-brown precipitate will be left. 

Characters and Tests.—Yellow crystals derived from the octohedron, permanent in the air, soluble in water, insoluble in alcohol. The aqueous solution gives a deep blue precipitate (ferric ferrocyanide ) with a ferric salt, a precipitate which is at first wUte (poti sio-ferrous ferrocyanidef), then light blue, and finally, by exposure to the air, dark blue,J with a ferrous salt and a reddish-brown precipitate (cupric ferrocyanide) with cupric sulphate. Heated with diluted sulphuric add, hydrocyanic acid vapours are evolved. 

White silver cyanide, thiocyanate, ferro- and yellow ferricyanide are decomposed with production of ignition-resistant silver. All metal ferro- and ferricyanides of the base metals leave a residue of ferric oxide and the particular metal oxide. For instance, the colorless ferrocyanides of zinc, cadmium, magnesium, calcium, barium, strontium, thorium etc. become yellow-brown Prussian blue and Turnbull s blue become dark (Fe304) and, later, brown (FegOg). Cupric ferricyanide (brown) and cupric ferrocyanide (violet-brown) are blackened when ignited because of the formation of cupric oxide. 

A. UltrafiUration. — By the use of filters that allow electrolytes to pass freely through, but retain the colloidal particles, colloidal stannic acid must have, after filtration, not only its ultramicrons, with their attendant anions, but also an equivalent amount of alkali ion molecules. The excess of the electrolytes, KOH, KaSnOa, etc., that were dissolved in the disperse medium, have passed through. The adsorbed portion of the alkali, regardless of whether it is dissociated or not, is an essential part of the hydrosol for if it is removed the colloid will coagulate. Duclaux, who has studied the behavior of colloidal iron oxide and cupric ferrocyanide in this connection, has proposed the name Micells for the ultramicrons together with their adsorbed molecules... 

The cupric ferrocyanide colloidal particles adsorb the ferrocyanide ion, become negatively charged as a result and go into solution. 

Thus it is seen that the cupric ferrocyanide carries down a part of the potassium ferrocyanide, and that the latter cannot diffuse into the surrounding liquid nor send off ion molecules because of dissociation. Duclaux believes this potassium ferrocyanide is chemically combined. This property is probably connected with the power of copper ferrocyanide to form scmipermeable membranes for crystalloids. 

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