Atomistry » Tin » Chemical Properties » Stannous Iodide
Atomistry »
  Tin »
    Chemical Properties »
      Stannous Iodide »

Stannous Iodide, SnI2

Stannous Iodide, SnI2, is obtained by adding potassium iodide in slight excess to a concentrated solution of stannous chloride, or by the action of hydriodic acid on tin; it crystallises in orange-red octahedra, which may be obtained by melting the compound, or evaporating its solution in carbon disulphide; but it is probably dimorphous. It melts at 320° C., and boils at 720° C. The dihydrate SnI2.2H2O is said to exist; 100 parts of water dissolve 0.93 parts of anhydrous stannous iodide at 20° C., and 4.03 parts at 100° C. It is much more soluble in hydriodic acid and alkali halide solutions, owing to the formation of a complex acid or salts.

When a solution of stannous chloride is titrated with iodine it is sometimes assumed that an additive reaction takes place with the formation of stannic iodochloride, SnCl2I2; but most likely a mixture of stannic chloride and iodide is produced thus:

2SnCl2 + 2I2 = SnCl4 + SnI4;

stannic iodide is, however, reduced to stannous iodide by excess of stannous chloride, thus:

SnI4 + 2SnCl2 = 2SnI2 + SnCl4.

Stannous iodide combines with hydrogen iodide to form iodostannous acid, HSnI3; and unstable, pale yellow needles of this substance separate at 0° C. from a saturated solution of stannous iodide in hydriodic acid. To this acid there correspond the iodostannites or stannoiodides: NaSnI3.3H2O, KSnI3.3H2O, NH4SnI3.3H2O, Sr(SnI3)2, and Ba(SnI3)2, which separate when the corresponding saline iodides are added to concentrated stannous chloride solution.

Stannous iodide combines with ammonia to form the compound SnI2.2NH3, which is yellow.

Last articles

Zn in 8PFC
Zn in 8SF0
Zn in 8SOJ
Zn in 8SOK
Zn in 8SYI
Zn in 8SLG
Zn in 8SEX
Zn in 8SEZ
Zn in 8SJG
Zn in 8SEY
© Copyright 2008-2020 by
Home   |    Site Map   |    Copyright   |    Contact us   |    Privacy