Silver nitrate solution

A compound of cobalt has the formula Co(NH3)jtCl. 0.500 g of it was dissolved in 50.00 cm M hydrochloric acid the excess acid required 40.00 cm M sodium hydroxide solution to neutralise it. Another 0.500 g portion of the compound was dissolved in water and allowed to react with excess silver nitrate solution. 0.575 g of silver chloride was precipitated. 

Hydrolysis of Ethyl Bromide. Add -a few drops of pure freshly distilled ethyl bromide to 2-3 ml. of aqueous silver nitrate solution in a test-tube and shake. Only a faint opalescence of silver bromide should be formed. -Now carefully warm the mixture in a small Bunsen flame, with gentle shaking silver bromide soon appears as a white suspension which rapidly increases in quantity and becomes a heavy precipitate. The ethyl bromide is thus moderately stable in cold water, but rapidly hydrolysed by hot water. 

Add a few drops of the distillate to an aqueous silver nitrate solution containing some dilute nitric acid and warm gently no silver chloride should be precipitated, indicating the complete absence of unchanged acetyl chloride. 

Reduction of ammoniacal silver nitrate. Place 2 ml. of dilute silver nitrate solution in a clean test-tube. Add 1 drop of NaOH solution and then add dil. ammonia drop by drop until the precipitate formed by the NaOH is just not redissolved. Now add 1-2 ml. of glucose solution and place the test-tube in a water-bath at 50-60° a silver mirror is produced in 1 - 2 minutes. 

Aliphatic mono-halides, and aromatic hydrocarbons with halogen in side-chain, precipitate silver hdide on treatment with cold aqueous silver nitrate solution. 

I. Reaction with cold silver nitrate solution. Add 2 ml. of 10% aqueous AgNOg solution to i ml. of methyl iodide and shake vigorously a yellow precipitate of Agl is formed in the cold. Add an excess of dil. HNO3 to show that the precipitate does not dissolve.f... 

Treat with ammoniacal silver nitrate solution and warm. 

Since the silver salts of the carboxylic acids are usually soluble in dilute nitric acid, they must be prepared by treating an aqueous solution of a neutral salt of the acid (and not the free acid itself) with silver nitrate solution. It is not practicable to attempt to neutralise the acid with sodium or potassium hydroxide solution, because the least excess of alkali would subsequently cause the white silver salt to be contaminated with brown silver oxide. The general method used therefore to obtain a neutral solution j to dissolve the acid in a small excess of ammonia solution, and then to boil the solution until all free... 

I he methyl iodide is transferred quantitatively (by means of a stream of a carrier gas such as carbon dioxide) to an absorption vessel where it either reacts with alcoholic silver nitrate solution and is finally estimated gravimetrically as Agl, or it is absorbed in an acetic acid solution containing bromine. In the latter case, iodine monobromide is first formed, further oxidation yielding iodic acid, which on subsequent treatment with acid KI solution liberates iodine which is finally estimated with thiosulphate (c/. p. 501). The advantage of this latter method is that six times the original quantity of iodine is finally liberated. 

Ammoniacal Silver Nitr. te. Add 1 drop of 10% aqueous NaOH solution to about 5 ml. of silver nitrate solution in a test-tube then add dilute NHg drop by drop with shaking until only a trace of undissolved Ag O remains. A number of reductions require the presence of Ag " ions. It is often advisable, therefore, after adding the ammonia to add silver nitrate solution until a faint but permanent precipitate is obtained. The solution should always be prepared in small quantities immediately before use, and any unexpended solution thrown away afterwards. If the solution is kept for some time, it may form explosive by-products. 

The cyanide content may be determined by titration with standard silver nitrate solution. ... 

Add dilute ammonia solution dropwise to 1 ml. of 0- N silver nitrate solution until the precipitate which forms just redissolves, and then dilute with 3 ml. of water. 

Do not heat the silver solution or allow it to stand even for a few hours, since explosive silver fulminate may be formed. The ammoniacal solution of silver nitrate is prepared by treating 3 ml. of 0-lN silver nitrate solution with very dilute ammonia solution dropwise until the precipitate which is first formed just redissolves. 

It must be noted, however, that nitroso, azoxy and azo compounds when subjected to the same treatment yield res])ectively hydroxylamines, hydrazo and hydrazine compounds, all of which reduce ammoniacal silver nitrate solution in the cold. 

Aromatic aldehydes react with the dimedone reagent (Section 111,70,2). All aromatic aldehydes (i) reduce ammoniacal silver nitrate solution and (ii) restore the colour of SchifiF s reagent many react with sodium bisulphite solution. They do not, in general, reduce Fehling s solution or Benedict s solution. Unlike aliphatic aldehydes, they usually undergo the Cannizzaro reaction (see Section IV,123) under the influence of sodium hydroxide solution. For full experimental details of the above tests, see under Ali-phalic Aldehydes, Section 111,70. They are easily oxidised by dilute alkaline permanganate solution at the ordinary temperature after removal of the manganese dioxide by sulphur dioxide or by sodium bisulphite, the acid can be obtained by acidification of the solution. 

The conversion of a diazo ketone to an acid amide may be accomplished by treating a warm solution in dioxan with 10-28 per cent, aqueous ammonia solution containing a small amount of silver nitrate solution, after which the mixture is heated at 60°-70° for some time. Precautions should be taken (by use of a. safety glass shield) when heating mixtures containing ammoniacal silver nitrate. 

Prepare the silver oxide by adding a dilute solution of sodium hydroxide to 10 per cent, silver nitrate solution until precipitation is just complete, avoiding an excess of edkali. Wash the precipitate several times by decantation finally, Ster at the pump and wash well with water. 

Sulphur, as sulphide ion, is detected by precipitation as black lead sulphide with lead acetate solution and acetic acid or with sodium plumbite solution (an alkaLine solution of lead acetate). Halogens are detected as the characteristic silver halides by the addition of silver nitrate solution and dilute nitric acid the interfering influence of sulphide and cyanide ions in the latter tests are discussed under the individual elements. 

Nitrogen and sulphur absent, (i) If only one halogen is present, acidify with dilute nitric acid and add excess of silver nitrate solution. A precipitate indicates the presence of a halogen. Decant the mother liquor and treat the precipitate with dilute aqueous ammonia solution If the precipitate is white and readily soluble in the ammonia solution, chlorine is present if it is pale yellow and difficultly soluble, bromine is present if it is yellow and insoluble, then iodine is indicated. Iodine and bromine should be confirmed by the tests given below. 

Place 2 ml. of the periodic acid reagent in a small test tube, add one drop (no more—otherwise the silver iodate, if formed, will fail to precipitate) of concentrated nitric acid, and shake well. Add one drop or a small crystal of the compound to be tested, shake the mixture for 15-20 seconds, and then add 1-2 drops of 3 per cent, silver nitrate solution. The instantaneous formation of a white precipitate of silver iodate is a positive test. Failure to form a precipitate, or the appearance of a brown precipitate which redissolves on shaking, constitutes a negative test. 

Phosphorus on the skin. Wash well with cold water and treat with 1 per cent, silver nitrate solution. 

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