Tin(II) chloride
- Tin dichloride
- Stannous chloride
- Easy - stannic chloride
- Stannous chloride (dihydrate )
- SnCl2 (anhydrous)
- SnCl2 · 2 H2O (dihydrate )
- 7772-99-8 (anhydrous)
- 10025-69-1 (dihydrate )
White rhombic crystals
Fixed
- 3.95 g · cm -3 ( anhydrous)
- 2.71 g · cm -3 ( dihydrate)
- 245-247 ° C ( anhydrous)
- 37.7 ° C ( dihydrate)
622-624 ° C ( anhydrous)
Readily soluble in water, ethanol and glacial acetic acid
Attention
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Tin ( II ) chloride ( obsolete: stannous chloride ) is a chloride of tin, the tin salt of hydrochloric acid. It forms colorless or off-white, greasy shiny crystals.
Production and representation
Anhydrous tin ( II ) chloride is obtained by heating tin in hydrochloric:
From aqueous solution, the dihydrate precipitates.
Add soda factories filling granulated tin in earthen vessels and manages hydrochloric acid vapors from the Sulfatöfen what one brings the discharged solution of tin (II ) chloride for crystallization. And tinplate waste, containing from three to five percent tin, tin ( II) chloride is obtained using hydrochloric acid vapors.
Tin ( II ) chloride is used as solid salt bulk or in solution on the market with excess hydrochloric acid. It is colorless, taste unpleasant metallic, is moist in the air, melts at 40 ° C, at 100 ° C completely or nearly anhydrous and acts with rapid heating to 100 ° C oxychloride, from the anhydrous at elevated temperature tin ( II) chloride was distilled off.
It is readily soluble in ethanol and in a little water, are more water an acid chloride and an insoluble, white, basic tin ( II ) chloride and only in the presence of hydrochloric acid, tartaric acid or ammonium chloride, a clear solution. The crystals and the solution absorbed in the air oxygen with formation of an insoluble, white oxychloride, which is reduced again in the presence of hydrochloric acid and tin.
Properties
In the pure state melts crystalline tin ( II) chloride at 247 ° C. Tin (II) chloride dihydrate melts at 40 ° C and evaporated at a higher temperature with decomposition. Tin ( II) chloride under UV light shows blue fluorescence.
Zinnspäne dissolve in warm hydrochloric acid, and the solution during evaporation are large, transparent crystals of tin (II ) chloride dihydrate. This tin salt is shown on a large scale by tin is dissolved in hydrochloric acid, the metal must be present in excess always, since the solution in the presence of some granulated tin to 75 or 78 ° C evaporates and brings the salt to crystallize.
Tin ( II) chloride is a strong reducing agent. Silver and mercury salts are reduced to the metals. Furthermore, it can reduce the salts of iron ( III) to iron ( II) salts or chromates to chromium ( III) salts.
Since tin (II ) ions are amphoteric, the Zinnhydroxychlorid may form (basic tin chloride ) in alkaline to slightly acidic solutions:
The so-called basic tin chloride is practically insoluble in water. This reaction is the reason why the fogging of aqueous Zinnchloridlösungen. By a slight acidification, for example, with hydrochloric acid or tartaric acid, the precipitation of the hydroxychloride can be prevented.
By atmospheric oxygen occurs readily in aqueous hydrochloric acid solution and the oxidation to tin ( IV ) chloride. The acidic conditions prevent the precipitation of basic tin salt:
Use
Tin ( II) chloride is used in the laboratory as a reducing agent. In electroplating, it is used for electrolytic tinning.
Tin ( II ) chloride is used in chemical analysis, in dyeing for the reduction of indigo and of iron and manganese to witnesses, as a mordant, in particular for dyeing with cochineal, for softening and Rosieren, also for the display of gold purple and paint colors as an anti- chlorine and for removing rust stains from laundry.
Tin ( II ) chloride dissolved in concentrated hydrochloric acid, is used in the Bettendorf 's test as evidence for arsenic. This leads to a brown coloration of the solution, as tin ( II ) chloride reduces the arsenic compound and so elemental arsenic precipitates. Interfering elements are only mercury and precious metals. This reagent can also detect sesame oil, since the solution with sesame oil turns red when sublayers.
In the food industry it is used as an antioxidant, acid and stabilizer, it prevents discoloration of white canned vegetables (eg asparagus). In the EU it is 512 approved exclusively for canned asparagus in jars or cans with a maximum limit of 25 mg / kg for the tin content in the final product as a food additive under the E number. It is in the usual amounts considered safe, in large quantities, however, gastrointestinal irritation are possible.