Tin (II) Chloride (100gr)
Tin(II) chloride, also known as stannous chloride, is a white crystalline solid with the formula SnCl2. It forms a stable dihydrate, but aqueous solutions tend to undergo hydrolysis, particularly if hot. SnCl2 is widely used as a reducing agent (in acid solution), and in electrolytic baths for tin-plating. Tin(II) chloride should not be confused with the other chloride of tin; tin(IV) chloride or stannic chloride (SnCl4).
SnCl2 has a lone pair of electrons, such that the molecule in the gas phase is bent. In the solid state, crystalline SnCl2 forms chains linked via chloride bridges as shown. The dihydrate is also three-coordinate, with one water coordinated on to the tin, and a second water coordinated to the first. The main part of the molecule stacks into double layers in the crystal lattice, with the “second” water sandwiched between the layers.
UsesA solution of tin(II) chloride containing a little hydrochloric acid is used for the tin-plating of steel, in order to make tin cans. An electric potential is applied, and tin metal is formed at the cathode via electrolysis.
It is used as a catalyst in the production of the plastic polylactic acid (PLA).
It also finds a use as a catalyst between acetone and hydrogen peroxide to form the tetrameric form of acetone peroxide.
- Sn2+ (aq) + 2 Ag+ → Sn4+ (aq) + 2 Ag (s)
A related reduction was traditionally used as an analytical test for Hg2+ (aq). For example, if SnCl2 is added dropwise into a solution of mercury(II) chloride, a white precipitate of mercury(I) chloride is first formed; as more SnCl2 is added this turns black as metallic mercury is formed. Stannous chloride can be used to test for the presence of gold compounds. SnCl2 turns bright purple in the presence of gold (see Purple of Cassius).
When mercury is analyzed using atomic absorption spectroscopy, a cold vapor method must be used, and tin (II) chloride is typically used as the reductant.
The Stephen reduction is less used today, because it has been mostly superseded by diisobutylaluminium hydride reduction.
Molten SnCl2 can be oxidised to form highly crystalline SnO2 nanostructures.