Silver ammonia complex bromide

Ores of silver native silver, argentite, cerargyrite (horn silver). Metallurgy of silver cyanide process, amalgamation process, Parkes process. O mpoimds of silver silver oxide, silver chloride, silver bromide, silver iodide, silver ammonia complex, silver cyanide complex, silver thiosulfate complex, silver nitrate. 

Silver chloride is readily soluble in ammonia, the bromide less readily and the iodide only slightly, forming the complex cation [Ag(NH3)2]. These halides also dissolve in potassium cyanide, forming the linear complex anion [AglCN) ] and in sodium thiosulphate forming another complex anion, [Ag(S203)2] ... 

In a second procedure, useful for forming reversal or direct X-ray emulsions, a high concentration of ammonia is used to form a complex precipitate with silver bromide, by mixing ammoniacal silver nitrate and ammoniacal potassium bromide. Dilution with water decomposes the ammonia complex, and silver bromide grains form.9... 

The silver chloride precipitate has to be separated from the original test solution since the ions present here, e.g., the cation of the substance to be examined, can disturb the complexation. Compared to the silver salts of bromide and iodide, silver chloride is the least insoluble. So the formation constant in the above complexation wins in the competition for the silver ion. Silver iodide is more insoluble, and here the precipitate dissolves in ammonia only with difficulty. The silver iodide is not soluble in ammonia at all. 

The precipitate is suspended in 2 ml of water R, and 1.5 ml of ammonia R is added. The precipitate must not dissolve. Silver iodide, compared to silver chloride and bromide, is relatively insoluble. So, where these two salts would dissolve because the silver ion forms a complex with ammonia, is not the case with silver iodide. The reason for isolating the precipitate is to avoid the ions of the original test solution, which could disturb the complex formation. 

Softer Lewis bases have to be applied in etch baths for oxides and salts of metals or semiconductors with a softer Lewis acid character of their cations. Materials consisting of compounds of heavier metals frequently become dissolvable in the presence of higher halogenide imis like chloride or bromide. So, Cu(l) which is not well solvated in water as the unbound ion becomes dissoluble in the presence of, for example, chloride ions by forming Cu(l) chlorocomplexes. The choice of suitable complex ligands depends on the particular coordination chemistry of the heavier metals or semiconductors inside the oxidic or saltlike functional materials. In some cases, ammonia or amines are suitable. So, the formatiOTi of a silver diamine complex can be used for the etching of Ag(l) compounds,... 

Only three simple silver salts, ie, the fluoride, nitrate, and perchlorate, are soluble to the extent of at least one mole per Hter. Silver acetate, chlorate, nitrite, and sulfate are considered to be moderately soluble. AH other silver salts are, at most, spatingly soluble the sulfide is one of the most iasoluble salts known. SHver(I) also forms stable complexes with excess ammonia, cyanide, thiosulfate, and the haUdes. Complex formation often results ia the solubilization of otherwise iasoluble salts. Silver bromide and iodide are colored, although the respective ions are colorless. This is considered to be evidence of the partially covalent nature of these salts. 

Silver Bromide. Silver bromide, AgBr, is formed by the addition of bromide ions to an aqueous solution of silver nitrate. The light yellow to green-yeUow precipitate is less soluble in ammonia than silver chloride, but it easily dissolves in the presence of other complexing agents, such as thiosulfate ions. 

The formation of a complex can also remove an ion and disturb the solubility equilibrium until more solid dissolves. We first met complexes in Section 2.13, where we saw that they were species formed by the reaction of a Lewis acid and a Lewis base. In this section, we consider complexes in which the Lewis acid is a metal cation, such as Ag+. An example is the formation of Ag(NH3)2+ when an aqueous solution of the Lewis base ammonia is added to a solution of silver bromide ... 

On treatment with aqueous silver nitrate it forms a stable crystalline complex (78), from which 75 can be recovered almost quantitatively by addition of ammonia ". Anhydrous nickel(ii) bromide converts cyclooctyne into the trimer (79) with a quantitative yield . However, when the reaction was carried out in the presence of a trace of water, the dimeric cyclobutadiene-nickel bromide complex (80) was obtained in 9-4% yield, together with 79 (85%) . The spectroscopic properties of 80 showed close similarity with those of the tetramethylcyclobutadiene-nickel chloride complex . 

A second area in which polarization effects show up is the solubility of salts in polar solvents such as water. For example, consider the silver halides, in which we have a polarizing cation and increasingly polarizable anions. Silver fluoride, which is quite ionic, is soluble in water, but the less ionic silver chloride is soluble only with the inducement of complexing ammonia. Silver bromide is only slightly soluble and silver iodide is insoluble even with the addition of ammonia. Increasing covaicney from lluoride to iodide is expected and decreased solubility in water is observed. 

The selectivity of the test is quite limited, even compared to the specificity seen in the identification test for chlorides. In the identification three criteria have to be fulfilled to qualify for a positive reaction. The unknown should give a white (curdled) precipitate formed upon addition of silver nitrate, which is insoluble in dilute nitric acid but redissolves in ammonia. In the limit test 2.4.4. Chlorides any substance capable of giving a white or weakly colored precipitate in dilute nitric acid will give a response like chloride, and this should be remembered in case of an xmexpected result. For the sake of example the following ions and substances are capable of giving a false positive reaction bromide, iodide, bromate, iodate, sulfite, chlorate, oxalate, and benzoate. In addition to this a variety of more complex organic substances are likely to precipitate, for example, alkaloids. 

Recall that silver chloride is soluble in an excess of chloride ions by the formation of the ion complex chlorosilver(I) (see Chap. 25). Bromide ions give a clear yellow color of silver bromide that dissolves in the same reagents as the chloride ion but with more difficulty. Iodide ions give a silver iodide precipitate insoluble in ammonia but soluble in potassium cyanide and sodium thiosulfate. From another standpoint, Ag+ ions give silver dithizonate with dithizone. The... 

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