Aurous iodide

Gold-hydroxyd, n. gold hydroxide, specif, auric hydroxide, gold(III) hydroxide, -jodid, n. gold iodide, specif, auric iodide, gold(III) iodide, -jodiir, n. aurous iodide, gold (I) iodide, -kafer, m. gold beetle. 

Monammino-aurous chloride is a white crystalline powder, sparingly soluble in water, soluble in an aqueous solution of ammonia, and precipitated by the addition of hydrochloric acid. It is unstable in the dry state, and decomposes completely on heating between 150° and 200° C. Aurous bromide and aurous iodide also unite with ammonia. The former yields only one ammino-derivative, the diammine, [Au(NII3)g]Br, and the latter two ammino-derivatives, namely, heAmmino-aurous iodide, [Au(NH3)6]I, and monammino-aurous iodide, [Au(NH3)]I. 

Hexammino-aurous Iodide, [Au(NH3)6]I.—When liquid or gaseous ammonia is allowed to act upon aurous iodide a white crystalline or powdery substance is obtained containing ammonia and having the composition AuI.6NH3. It decomposes at —28° C. under ordinary pressure, and if heated from —28° C. to +20° C. it loses five molecules of ammonia and is transformed into the monammine, [Au(NII3)]I. 

In 1819 Pelletier 2 found Au=288 by analysing aurous iodide. Two years later, Javal3 found Au=201 by analysing auric oxide, and Au=104 by analysing potassium aurichloride. In 1823 Figuier4 found Au = 179 from the analysis of sodium aurichloride. These very inaccurate results are in striking contrast to Berzelius s value. 

Aurous iodide is a lemon-yellow powder, and is very difficult to prepare in the pure state, as it is decomposed by moist air at ordinary temperatures. The excess of iodine is best eliminated by sublimation at 30° C. It is decomposed by heating with water, dilute sulphuric acid,... 

Aurous cyanide forms yellow, microscopic laminae, very slightly soluble in Water. It is more stable than aurous iodide, but at red heat is decomposed into gold and cyanogen. Its insolubility renders it immune to the action of dilute acids and hydrogen sulphide, but solutions of ammonia, potassium hydroxide, ammonium sulphide, and sodium thiosulphate dissolve it, probably forming complex derivatives. In aurous cyanide the tendency to form complex compounds is much more marked than in the corresponding chloride, bromide, and iodide.3 Its interaction with potassium ferrocyanide has been studied by Beutel.4... 

On drying, the dark-green product decomposes into aurous iodide and iodine. It is soluble with difficulty in water to an unstable solution. 

Auri-iodic Acid, HAuI4.—Hydrogen iodide converts aurous iodide, auric iodide, and gold in presence of free iodine into auri-iodic acid. It forms small, black crystals. 

Metallurgy of gold. Aurous chloride, aurous bromide, aurous iodide, potassium aurous cyanide, auric chloride, hydrogen aurichloride. 

The radii in the lowest row of the table were obtained by a number of approximate considerations. For instance, if we assume the bismuth radius to bear the same ratio to the interatomic distance in elementary bismuth as in the case of arsenic and antimony, we obtain (Bi) = 1.16— 1.47 A. A similar conclusion is reached from a study of NiSb and NiBi (with the nickel arsenide structure). Although the structures of the aurous halides have not been determined, it may be pointed out that if they are assumed to be tetrahedral (B3 or Bi) the interatomic distances in the chloride, bromide, and iodide calculated from the observed densities1) are 2.52, 2.66, and 2.75 A, to be compared with 2.19, 2.66, and 2.78 A, respectively, from pur table. 

Atoioioltv of gold, 174 AurioaiuiTdi 174 ohloridok 174 H iodide, 174 oid, 174 sulphide, 174 Aurous ohlorids, 174 iodi 174 oxide, 174 sulphide, 174 Compounds of gold, 174 Fotassioeotsie, 174 fltaiu, 34. 

Tetrachloroauric(III) acid in aqueous ethanol reacted with an excess of the phosphine-arsine undergoing reduction and chelation to give the cation, LXVII, precipitated as the colorless, highly stable iodide. The 4-coordinate aurous atom in this compound has the tetrahedral configuration, and attempts were made to resolve the cation into optically active forms. Fractional recrystallization of eight salts having different optically-active anions failed to give any indication of resolution. 

Aurous chloride, formed by heating Au2Cl6 at 160°, is a yellow powder which" dissociates- aT higher temperatures and is decomposed by water the iodide has chains I—Au—I—Au— with linear I—Au—I bonds. 

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