Potassium-cyanide sentence example

potassium-cyanide
  • It is insoluble in dilute acids, but is readily soluble in excess of potassium cyanide.

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  • Potash solution converts it into a mixture of potassium cyanide and cyanate.

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  • Many esters of malonic acid have been prepared, the most important being the diethyl ester (malonic ester), CH 2 (000C 2 H 5) 2, which is obtained by dissolving monochloracetic acid in water, neutralizing the solution with potassium carbonate, and then adding potassium cyanide and warming the mixture until the reaction begins.

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  • The half nitrile of malonic acid is cyanacetic acid, CN CH 2 COOH, which, in the form of its ester, may be obtained by the action of a solution of potassium cyanide on monochloracetic acid.

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  • Held synthesized the acid from ethyl chlor-acetoacetate (from chlorine and acetoacetic ester) by heating with potassium cyanide and saponifying the resulting nitrile.

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  • Filter from the bismuth hydrate, and if copper is present, add potassium cyanide till the colour is destroyed, then pass sulphuretted hydrogen, and cadmium is precipitated as the yellow sulphide.

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  • The concentration of the simple copper ions is then so much diminished that the copper plate becomes an anode with regard to zinc. Thus the cell - copper I potassium cyanide solution I potassium sulphate solution - zinc sulphate solution I zinc - gives a current which carries copper into solution and deposits zinc. In a similar way silver could be made to act as anode with respect to cadmium.

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  • For this reason the acid copper-bath is not used for iron or zinc objects, a bath containing copper cyanide or oxide dissolved in potassium cyanide being substituted.

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  • When heated with alcoholic potassium cyanide they are converted into benzoins.

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  • Tin compounds when heated on charcoal with sodium carbonate or potassium cyanide in the reducing blowpipe flame yield the metal and a scanty ring of white Sn02.

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  • An important nucleus-synthetic reaction is the saponification of nitriles, which may be obtained by the interaction of potassium cyanide with a halogen substitution derivative or a sulphonic acid.

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  • It is also obtained by the action of hydrogen peroxide on hydrocyanic acid, or of manganese dioxide and sulphuric acid on potassium cyanide.

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  • This salt is prepared by precipitating a solution of gold in aqua regia by ammonia, and then introducing the well-washed precipitate into a boiling solution of potassium cyanide.

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  • Potassium auricyanide, 2KAu(CN) 4.3H 2 O, is obtained as large, colourless, efflorescent tablets by crystallizing concentrated solutions of auric chloride and potassium cyanide.

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  • The addition of potassium cyanide has been suggested to assist the amalgamation and to prevent " flouring," but Skey has shown that its use is attended with loss of gold.

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  • The action proceeds in two stages; in the first hydrogen peroxide and potassium aurocyanide are formed, and in the second the hydrogen peroxide oxidizes a further quantity of gold and potassium cyanide to aurocyanide, thus (1) 2Au+4KCN +02+2H20=2KAu(CN)2+4KOH+H202;(2)2Au+4KCN+2H202= 2KAu(CN) 2 +4KOH.

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  • It may be noticed that the potassium zinc cyanide is useless in gold extraction, for it neither dissolves gold nor can potassium cyanide be regenerated from it.

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  • Lead cyanide, Pb(NC) 2, however, does not form such a salt, and is insoluble in potassium cyanide solution.

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  • Silver cyanide, AgNC, is formed as a white precipitate by adding potassium cyanide to silver nitrate solution; or better, by adding silver nitrate to potassium silver cyanide, KAg(NC) 2, this double cyanide being obtained by the addition of one molecular proportion of potassium cyanide to one molecular proportion of silver nitrate, the white precipitate so formed being then dissolved by adding a second equivalent of potassium cyanide.

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  • The double cyanides formed by the solution of the cyanide of a heavy metal in a solution of potassium cyanide are decomposed by mineral acids with liberation of hydrocyanic acid and formation of the cyanide of the heavy metal.

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  • Silver nitrate gives a white precipitate with cyanides, soluble in excess of potassium cyanide.

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  • Cyanogen compounds of chromium, analogous to those of iron, have been prepared; thus potassium chromocyanide, K 4 Cr(CN) 6.2H 2 0, is formed from potassium cyanide and chromous acetate; on exposure to air it is converted into the chromicyanide, K 3 Cr(CN) 6, which can also be prepared by adding chromic acetate solution to boiling potassium cyanide solution.

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  • Diazobenzenecyanide, C 6 H 5 N 2 CN, is an unstable oil, formed when potassium cyanide is added to a solution of a diazonium salt.

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  • Succinonitrile, C2H4(CN)2r is obtained by the action of potassium cyanide on ethylene dibromide or by the electrolysis of a solution of potassium cyanacetate.

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  • The potassium cyanide method is based on the fact that, when potassium cyanide is added to an ammoniacal solution of a salt of copper, the insoluble copper cyanide is formed, the end of the reaction being indicated by the disappearance of the blue colour of the solution.

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  • To the filtrate (or, if no silver is present, to the diluted nitric acid solution) io cc. of ammonia are added, and a standard solution of potassium cyanide is run in from a burette until the blue colour has nearly disappeared.

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  • The potassium cyanide solution is standardized by dissolving 0.5 gramme o£ pure copper in 5 cc. of nitric acid, diluting, adding io cc. of ammonia, and titrating exactly as described above.

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  • It readily dissolves in ammonia, the solution, on evaporation, yielding rhombic crystals of 2AgC1.3NH 3; it also dissolves in sodium thiosulphate and potassium cyanide solutions.

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  • Meyer (Ber., 1902, 35, p. 1 59 1) by the electrolysis of silver selenite in the presence of potassium cyanide obtained the value 79.22.

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  • He died in 1954 from taking potassium cyanide at his home where he was performing electrolysis experiments.

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  • Death was clearly caused by taking a very large quantity of potassium cyanide.

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  • On the addition of potassium cyanide they give a brown precipitate of cobalt cyanide, Co(CN) 2, which dissolves in excess of potassium cyanide to a green solution.

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  • Cobaltous cyanide, Co(CN)2.3H20, is obtained when the carbonate is dissolved in hydrocyanic acid or when the acetate is precipitated by potassium cyanide.

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  • Hydrocobaltocyanic acid is not known, but its potassium salt, K4Co(CN) 6, is formed when freshly precipitated cobalt cyanide is dissolved in an ice-cold solution of potassium cyanide.

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  • It is also obtained in the action of potassium cyanide on gold in the presence of air, a reaction utilized in the MacArthur-Forrest process of gold extraction (see below).

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  • The remedy is to spray with kerosene emulsion or whale-oil soap; or if on cucumbers or tomatoes, it is best to fumigate with hydrocyanic acid gas, using one ounce of potassium cyanide to each woo cubic ft.

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