Silver residues

Silver chloride is reduced to the metal by zinc. One of the methods of recovering silver from silver residues depends on this. The residue is first treated with concentrated hydrochloric acid and then sulphuric acid and zinc added ... 

Add, with stirring, a solution of 6 8 g. of the fiis-diazo ketone in 100 ml. of warm dioxan to a suspension of 7 0 g. of freshly precipitated silver oxide in 250 ml. of water containing 11 g. of sodium thiosulphate at 75°. A brisk evolution of nitrogen occurs after 1 5 hours at 75°, filter the liquid from the black silver residue. Acidify the almost colourless filtrate with nitric acid and extract the gelatinous precipitate with ether. Evaporate the dried ethereal extract the residue of crude decane-1 10-dicarboxylic acid weighs 4 -5 g. and melts at 116-117°. RecrystaUisation from 20 per cent, aqueous acetic acid raises the m.p. to 127-128°. 

A simple and economical method for recovering silver residues by dissolution in used photographic fixer (thiosulfate) solution, then precipitation by addition of zinc powder, is detailed [1]. After the acid digestion phase of silver recovery operations, addition of ammonia followed immediately by addition of ascorbic acid as reducant gives a near-quantitative recovery of silver metal, and avoids the possibility of formation of silver nitride [2],... 

Overstained gels must be freed from acidic and/or silver residues by washing with several changes of ddH2 0. Then the staining can be reduced or removed according to Protocol 2.4.2.7. A new silver stain is possible, but you never get the same picture as at the first time therefore, the weakening should be done only if absolutely necessary. 

The silver residues are saved for the recovery of silver and iodine. 

Recovery of silver residues as AgN03 [use protective shield during the whole of this procedure]... 

The dried silver residue is treated with aqua regia (Care Hood ). After action has ceased the solution is filtered through glass wool and the residue is washed to... 

Silicon, higher chlorides of, 42 Silicon tetrabromide, 38, 40 Silicon tetrachloride, 44 Silicopropane, octachloro, 44 Silicotungstic acid, 129 analysis, 131 ether complex, 131 Silver, metallic, 4 Silver chloride, reduction of, 3 Silver cyanamide, 98 Silver residues, purification of, 2 Sodium amalgam, 10 Sodium amide, 74 Sodium azide, purification of, 79 Sodium azidodithiocarbonate, 82 Sodium butoxide, 88 Sodium hypochlorite (solution), 90 Sodium iodate, 168 Sodium metaperiodate, 170 Sodium paraperiodate, chlorine method, 169 persulfate method, 170 Strontium amalgam, 11 Sulfur hexafluoride, 121 Sulfuryl chloride, 114... 

Miss Frush and IsbelF used crystalline heptaacetyl-a-neolactosyl chloride in the Konigs-Knorr reaction under conditions identical with those described for pentaacetyl-a-D-(a)-guloheptosyl bromide, with the exception that the reaction time was increased to seventy-two hours. Acid and alkaline hydrolysis of the reaction solution showed that only about 70% of the original sugar was present, and that this was almost completely in the form of the orthoester. By extraction of the silver residues with chloroform, a halogen-free sirup was obtained, from which short rectangular crystals separated upon addition of methyl alcohol. This substance was methyl /3-neolactoside heptaacetate, which exhibited the expected normal behavior. 

Do not pour silver residues dowm the drain Silver and silver compounds kill microorganisms in sewage treatment plants. The silver and silver residues are collected, dissolved in concentrated nitric acid and treated with hydrochloric-acid (1 1). The i Cl precipitate is allowed to settle, the mother liquor decanted off and filtered, the precipitate again treated wnth hydrochloric acid (1 1) in a beaker, and the Ag ions reduced by means of /.inc rods. I he silver precipitate formed i.s filtered, washed free of chloride ions and zinc and either fused with borax or converted to AgNOj. 

Suppose the silver residues contained salts of lead and copper would these contaminate the silver nitrate Explain your answer. 

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