Solubility silver cyanide

Silver Cyanide. Silver cyanide, AgCN, forms as a precipitate when stoichiometric quantities of silver nitrate and a soluble cyanide are mixed. Sdver(I) ion readily forms soluble complexes, ie, Ag(CN) 2 01 Ag(CN) 2> die presence of excess cyanide ion. 

Silver cyanide [506-64-9] M 133.9, m dec at 320 , d 3.95. POISONOUS white or grayish white powder. Stir thoroughly with H2O, filter, wash well with EtOH and dry in air in the dark. It is very insoluble in H2O (0.000023g in lOOmL H2O) but is soluble in HCN or aqueous KCN to form the soluble Ag(CN) complex. [Chem Ber 72 299 I939 J Am Chem Soc 52 184 1930.]... 

A soluble cyanide added to silver nitrate solution precipitates silver cyanide as an ionic compound ... 

With the salts of certain weak acids, such as carbonic, sulphurous, and nitrous acids, an additional factor contributing to the increased solubility is the actual disappearance of the acid from solution either spontaneously, or on gentle warming. An explanation is thus provided for the well-known solubility of the sparingly soluble sulphites, carbonates, oxalates, phosphates(V), arsenites(III), arsenates(V), cyanides (with the exception of silver cyanide, which is actually a salt of the strong acid H[Ag(CN)2]), fluorides, acetates, and salts of other organic acids in strong acids. 

When potassium cyanide solution is added to a solution of silver nitrate, a white precipitate of silver cyanide is first formed because the solubility product of silver cyanide ... 

This complex ion dissociates to give silver ions, since the addition of sulphide ions yields a precipitate of silver sulphide (solubility product 1.6 x 10 49 mol3 L 3), and also silver is deposited from the complex cyanide solution upon electrolysis. The complex ion thus dissociates in accordance with the equation ... 

Discussion. The theory of the titration of cyanides with silver nitrate solution has been given in Section 10.44. All silver salts except the sulphide are readily soluble in excess of a solution of an alkali cyanide, hence chloride, bromide, and iodide do not interfere. The only difficulty in obtaining a sharp end point lies in the fact that silver cyanide is often precipitated in a curdy form which does not readily re-dissolve, and, moreover, the end point is not easy to detect with accuracy. 

Hydrogen cyanide (Table 15.1) is a colorless, flammable liquid or gas that boils at 25.7°C and freezes at minus 13.2°C. The gas rarely occurs in nature, is lighter than air, and diffuses rapidly. It is usually prepared commercially from ammonia and methane at elevated temperatures with a platinum catalyst. It is miscible with water and alcohol, but is only slightly soluble in ether. In water, HCN is a weak acid with the ratio of HCN to CN about 100 at pH 7.2, 10 at pH 8.2, and 1 at pH 9.2. HCN can dissociate into H+ and CN. Cyanide ion, or free cyanide ion, refers to the anion CN derived from hydrocyanic acid in solution, in equilibrium with simple or complexed cyanide molecules. Cyanide ions resemble halide ions in several ways and are sometimes referred to as pseudohalide ions. For example, silver cyanide is almost insoluble in water, as are silver halides. Cyanide ions also form stable complexes with many metals. 

Ocular Effects. Acute exposure to cyanogen gas produced eye irritation in volunteers (McNemey and Schrenk 1960). Similarly, chronic exposure to cyanide in the working environment caused eye irritation in exposed individuals (Blanc et al. 1985). In addition, exposure to potassium silver cyanide caused ocular opacity in exposed animals, but comeal opacity is also a sign of excessive exposure to soluble silver salts alone. However, when cyanide was applied to a rabbit s eye, keratitis developed regardless of the chemical form of cyanide used (Ballantyne 1983b). 

List of Hazardous Substances and Reportable Quantities Ammonium thiocyanate Calcium cyanide, cyanogen chloride, sodium cyanide, copper cyanide Cyanides (soluble salts complexes) Cyanogen Potassium silver cyanide 5,000 lbs 10 lbs 10 lbs 100 lbs 1 lb 40 CFR 302.4 EPA 1985e... 

D-Lyxose diacetamide. Ammonia-silver oxide.y Ten grams of pentaaoetyl-n-galactononitrile was dissolved in 30 ml. of ethanol, and a solution of silver oxide (from 5 g. of silver nitrate) in 50 ml. of 30 % ammonia added. After two days at room temperature, the precipitated silver cyanide was removed by filtration and the solution evaporated in vacuo at 40° imtil all ammonia was eliminated. The residue was diluted with water and the soluble silver eliminated by treatment with hydrogen sulfide and filtration. The filtrate was treated with decolorizing carbon, filtered and evaporated to dryness. When the residue crystallized, it was suspended in warm ethanol and filtered yield, 2.5 g. (40%). After recrystallization from 60% ethanol, the product had a melting point of 230-231°. 

Cyanogen Trisulphide, (CN)2S3 or (CN)6S .—The non-volatile residue which is formed when silver cyanide acts on sulphur chloride constitutes cyanogen trisulphide. It is a dark yellow crystalline powder, insoluble in water, alcohol, ether, carbon disulphide and chloroform. It is unattacked by hydrochloric acid and is soluble in concentrated sulphuric acid. It is transformed into carbon dioxide and sulphuric acid by nitric acid or aqua regia. When distilled, the products are carbon disulphide, sulphur and tricyanuramide, N8(C3N3)3.1... 

Cyanide. Sodium cyanide. [CAS 143-33-9]. NaCN. white solid, soluble, very poisonous, formed (1) by reaction of sodamide and carbon at high temperature, (2) by reaction of calcium cyanamide and sodium chloride at high temperature, reacts in dilute solution in air with gold or silver to form soluble sodium gold or silver cyanide, and used for this purpose in the cyanide process for recovery of gold. The perceniage of available cyanide is greater than in potassium cyanide previously used. Used as a source of cyanide, and for hydrocyanic acid. 

Silver cyanide is soluble in a solution of potassium cyanide, also forming a double salt, of the formula... 

The sulfide ores are commonly roasted with sodium chloride to form AgCl, which is then dissolved by leaching the ore with an aqueous solution of sodium or potassium cyanide. The chloride is dissolved because of the formation of soluble sodium silver cyanide [NaAg(CN)2]. The cyanide solution is treated with finely divided zinc, which displaces the silver from the complex cyanide. 

Silver nitrate solution white precipitate of silver cyanide, AgCN, readily soluble in excess of the cyanide solution forming the complex ion, dicyano-argentate(I) [Ag(CN)2] (cf. Section III.6, reaction 7) ... 

Silver cyanide is soluble in ammonia solution and in sodium thiosulphate solution, but is insoluble in dilute nitric acid. 

Chloride and cyanide in the presence of each other Both silver chloride and silver cyanide are insoluble in water, but soluble in dilute ammonia solution. Three methods are available for the detection of cyanide in the presence of chloride. 

Solution of silver or its cyanide in potassium cyanide forms potassium silver cyanide, KAg(CN)2, octahedral crystals stable in air, but blackened by light. As 20° C. its solubility is 25 grams per 100 grams of water.11... 

Formation of Complex Ions.—In certain cases the solubility of a sparingly soluble salt is greatly increased, instead of being decreased, by the addition of a common ion a familiar illustration of this behavior is provided by the high solubility of silver cyanide in a solution of cyanide ions. Similarly, mercuric iodide is soluble in the presence of excess of iodide ions and aluminum hydroxide dissolves in solutions of alkali hydroxides. In cases of this kind it is readily shown by transference measurements that the silver, mercury or other cation is actually present in the solution in the form of a complex ion. The solubility of a sparingly soluble salt can be increased by the addition of any substance, whether it... 

The potential of a silver electrode during the course of the titration of silver nitrate with potassium c an-ide is shown in Fig. 78 the first marked change of potential occurs when one equivalent of cyanide has been added to one of silver, so that the whole of the silver cyanide is precipitated, and the second, when two equivalents of cyanide have been added, corresponds to the complete formation of the Ag(CN)2 ion. It will be seen that the changes of potential occur very sharply in each case this means that the silver cyanide is very slightly soluble and that, t+vo complex ion is very stable. 

This forms white acicular crystals at 67° C. It is readily soluble in benzene, carbon disulphide and chloroform, but sparingly in alcohol and ether. This sulphide may also be obtained by the action of sodium sulphide on diphenyl chloroarsine in benzene solution on treatment with mercuric cyanide or silver cyanide, diphenyl cyanoarsine is obtained (see p. 314). 

Silver cyanide is a white solid readily formed as a precipitate when solutions of silver are treated with potassium cyanide. It is readily soluble in excess of potassium cyanide forming the double cyanide of silver and potassium. It is also soluble in ammonium hydroxide. 

The acute toxicity of metallic silver and water-soluble compounds is moderate. The oral LD50 in mice for colloidal silver was 100 mg kg and relatively similar for the water-soluble compounds silver nitrate (50-129 mg kg ) and silver cyanide (LD50 in rats, 125 mg kg ). Silver nitrate appears much less toxic in rabbits by the oral route (800 mg kg ). The insoluble silver oxide was reported to exhibit an LDlo of >2gkg Mn rats. 

Silver (Ag, at. mass 107.87) occurs in its compounds in the (I)- oxidation state. So far, silver(II) is only of limited value in spectrophotometry. Silver(I) -sulphide and -halides are sparingly soluble. Ammine, cyanide, and thiosulphate complexes of silver are formed. In the presence of excess of Cf or SCN , traces of silver form soluble complexes. 

In the Liebig titration of cyanide ion, a soluble complex is formed and at the equivalence point, solid silver cyanide is formed, signaling the end point ... 

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