Silver Iodate

Add 1 drop (0 05 ml.) of concentrated nitric acid to 2 0 ml. of a 0 5 per cent, aqueous solution of paraperiodic acid (HjIO,) contained in a small test-tube and shake well. Then introduce 1 op or a small crystal of the compound. Shake the mixture for 15 seconds and add 1-2 drops of 5 per cent, aqueous silver nitrate. The immediate production of a white precipitate (silver iodate) constitutes a positive test and indicates that the organic compound has been oxidised by the periodic acid. The test is based upon the fact that silver iodate is sparingly soluble in dilute nitric acid whereas silver periodate is very soluble if too much nitric acid is present, the silver iodate will not precipitate. 

In qualitative organic analysis, use is made of the fact that silver iodate is sparingly soluble in dilute nitric acid whereas silver periodate is very soluble. For water-insoluble compounds solutions in ethanol or in pure dioxan may be employed. 

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. 

Ha.la.tes, Silver chlorate, AgClO, silver bromate, AgBrO, and silver iodate, AglO, have been prepared. The halates may decompose explosively if heated. 

Silver diethyldithiocarbamate [1470-61-7] is a reagent commonly used for the spectrophotometric measurement of arsenic in aqueous samples (51) and for the analysis of antimony (52). Silver iodate is used in the determination of chloride in biological samples such as blood (53). 

Silver iodate [7783-97-3] M 282.8, m >200 , d 5.53. Washed with warm dilute HNO3, then H2O and dried at 100°, or recrystd from NH3 soln by adding HNO3, filtering, washing with H2O and drying at 100°. 

The saturated solution of silver iodate in water at 25°C has a molality equal to 0.00179, and the activity coefficient y in this saturated solution may be taken to be 0.989. The heat of solution tends at extreme dilution to the value +13,200 c d/mole Find in electron-volts per ion pair the value of L, and also the value of dL/dT in water at 25°C. 

With metalloids, the reactions are dangerous too. There are cases of accidents during which violent combustions or detonations occur with carbon, phosphorus, arsenic, sulphur and tellurium (with silver iodate, in this last case). Friction is one of the main factors. 

The potential for violence of interaction between the powerful reducing agent potassium and oxidant classes has been well described. Other miscellaneous oxygen-containing substances which react violently or explosively include sodium iodate, silver iodate, lead sulfate and boric acid. 

Mixtures of sodium with silver iodate or sodium iodate explode when initiated by shock. 

Filtering and Drying the Silver Halide.—First heat the precipitate in the beaker on the boiling water bath. Heat silver iodide (and bromide) for two hours, since silver iodide forms with silver nitrate a solid compound which is only gradually decomposed by water. Further, when determining iodine, first reduce with sulphurous acid solution the silver iodate produced during the decomposition. 

Mercury(I) bromate, 0271 Potassium iodate, 4619 Silver iodate, 0020 Sodium iodate, 4624 Zinc bromate, 0279 See Other METAL OXOHALOGENATES... 

Periodic acid is a stronger oxidizing agent than the others mentioned earlier in this chapter. It causes oxidative cleavage (fragmentation) of the carbon backbone. Normally a silver ion is present to facilitate the reaction through the precipitation of silver iodate (AglOj). 

Silicochloroform Silicolluoric Acid Silicon Chloride Silicone Fluids Silicon Tetrachloride Silver Acetate Silver Carbonate Silver Fluoride Silver Iodate Silver Monofluoride Silver Nitrate Silver Oxide Silver Sulfate Silvisar 510 Slaked Lime Slow-Curing Asphalt Sodamide Sodium... 

Iodine trichloride.—This compound was discovered by J. L. Gay Lussac as the result of treating warm iodine or iodine monochloride with an excess of chlorine. The trichloride collects as a citron-yellow crystalline sublimate on the cooler parts of the vessel. It is also formed by the action of liquid chlorine on iodine, or an iodide—say lead iodide.18 The iodine trichloride is almost insoluble in liquid chlorine, and hence, say Y. Thomas and P. Dupuis, this method of preparation is very convenient. It is also formed by the action of dry chlorine on hydrogen iodide (A. Christomanos) silver iodate (J. Krutwig) or methyl iodide (L. von... 

Silver foil is transformed by an aq. soln. of the trichloride into silver chloride and iodide silver oxide with an excess of the trichloride is transformed into the chloride and iodic acid with more silver oxide, silver iodate is formed and with an excess of the oxide and a boiling soln. some silver periodate is formed. Mercuric oxide is slowly transformed into mercuric chloride and oxide chlorine, oxygen, and possibly chlorine monoxide are evolved. Aq. soln. of the trichloride give a precipitate of iodine with a little stannous chloride with more stannous chloride, some stannous iodide is formed. Consequently, although chloroform extracts no iodine from the aq. soln., it will do so after the addition of stannous chloride. Sulphur dioxide and ferrous sulphate are oxidized. 

Detection and determination.—The periodates behave towards reducing agents like the iodates. They are usually but slightly soluble in water and readily soluble in dil. nitric acid. When soln. of sodium periodate are added to barium, strontium, calcium, lead, and silver salts, precipitates of dimesoperiodates are obtained, and the mother liquor has an acid reaction—the silver salt is pale yellow, the others white—silver iodate is also white. The silver precipitate becomes dark red when boiled in water the fresh precipitate is very soluble in ammonia, the dark red... 

The second of the three types of qualitative teste mentioned above involves acid-catalyzcd cleavage of an epoxide with periodic acid.38 The IOf ion then oxidizes the resulting 1,2-diol in the usual manner, while itself undergoing reduction to iodato. In the presence of AgH ion, the gradual formation of iodate will be marked by precipitation of silver iodate (Eq. 983). An obvious drawback to this procedure is that any other functional groups capable of reducing IOf iou will interfere with epoxide detection. 

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