Chemical elements
    Physical Properties
    Chemical Properties
      Indium Trifluoride
      Indium monochloride
      Indium dichloride
      Indium trichloride
      Indium oxychloride
      Indium monobromide
      Indium tribromide
      Indium oxybromide
      Indium mono-iodide
      Indium di-iodide
      Indium tri-iodide
      Indium perchlorate
      Indium iodate
      Indium sesqui-oxide
      Indium hydroxide
      Indium monosulphide
      Indium disulphide
      Indium sesquisulphide
      Indium trisulphide
      Basic indium sulphite
      Indium sulphate
      Indium sesquiselenide
      Indium selenite
      Indium selenate
      Indium telluride
      Indium silicotungstates
      Indium nitrate
      Indium phosphide
      Indium platinocyanide
      Indium oxalate
      Indium acetylacetonate
    PDB 1ind-1ind

Chemical Properties of Indium

Indium is unaffected by dry air at ordinary temperatures, but at a red heat it burns with a blue flame, producing the sesqui-oxide with the liberation of 1044.6 cals. of heat per gram of metal. It unites directly with sulphur and the halogens. It is unaffected by boiling water or potassium hydroxide, but dissolves in mineral acids. The action of nitric acid is slow, and ammonia is found among the reduction products of the acid. The potential differences between indium and molar, tenth-molar, and hundredth-molar solutions of indium trichloride are 0.094, 0.108, and 0.119 volts respectively at 25°, the metal being negative to the solution. The electrolytic solution-pressure of indium, 102 to 103 atmospheres, places it between iron and lead in the electromotive series.

Compounds of Indium

Indium forms derivatives corresponding to the three types InX, InX2, and InX3 (X denoting a univalent acid radicle), but only the compounds of the last type are capable of existing in aqueous solution, in which they are appreciably hydrolysed. The solutions contain the colourless ion In•••. The ions In and In•• appear to be unstable and to undergo change as represented by the equations

conductivity comparison
Comparison of conductivities of indium chloride and bromide solutions with those of cadmium bromide and nitrate.
3In = In••• + 2In;
3In•• = 2In••• + In.

Thus the lower halogen derivatives of indium are decomposed by water, metallic indium being deposited.

The trihalides of indium appear to resemble the corresponding compounds of cadmium in their ability to form complex anions in solution, a resemblance which is not surprising since indium and cadmium occupy adjacent positions in the periodic table. The variation of the equivalent conductivity (A) with the cube root of the concentration (m, in gram-equivalents per litre) is shown for the four salts InCl3, InBr3, CdBr2, and Cd(NO3)2 in fig. The abnormally low values for A in solutions of moderate concentration is shown in each case except that of cadmium nitrate, and this salt does not form complex anions in solution. The low values for indium chloride are all the more remarkable since the data plotted refer to a temperature of 25°, the other data holding good for 18° C.
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