Tin (II) chloride

Crystal structure
	__ Sn 2+ __ Cl -
General
Surname	Tin (II) chloride
other names	Tin dichloride; Tin chloride; Single chlorine tin; Stannous chloride (dihydrate); STANNOUS CHLORIDE ( INCI ) ; E 512 ;
Ratio formula	SnCl 2 (anhydrous); SnCl 2 2 H 2 O (dihydrate);
Brief description	white rhombic crystals
External identifiers / databases
EC number	231-868-0
ECHA InfoCard	100,028,971
PubChem	24479
ChemSpider	22887
DrugBank	DB11056
Wikidata	Q204964
properties
Molar mass	189.61 g · mol -1 (anhydrous); 225.64 g mol −1 (dihydrate);
Physical state	firmly
density	3.95 g cm −3 (anhydrous); 2.71 g cm −3 (dihydrate);
Melting point	246 ° C (anhydrous); 37.7 ° C (dihydrate);
boiling point	623 ° C (anhydrous)
solubility	easily soluble in (degassed) water (2700 g · l −1 at 20 ° C), ethanol and glacial acetic acid
safety instructions
H and P phrases	H: 290-302-332-314-317-335-373-412
	P: 280-301 + 330 + 331-303 + 361 + 353-304 + 340-305 + 351 + 338-310
Toxicological data	700 mg kg −1 ( LD 50 , rat , oral )
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Tin (II) chloride (outdated: tin chloride ) is a chloride of tin , the tin salt of hydrochloric acid . It forms colorless or gray-white, greasy, shiny crystals .

Extraction and presentation

Anhydrous tin (II) chloride is obtained by heating tin in hydrogen chloride :

{\ displaystyle \ mathrm {Sn + 2 \ HCl \ longrightarrow SnCl_ {2} + H_ {2}}}

The dihydrate precipitates from aqueous solution .

In soda factories, granulated tin is filled into earthenware vessels and hydrochloric acid vapors are introduced from the sulfate ovens, whereupon the drained solution of tin (II) chloride is made to crystallize. Tin (II) chloride with hydrochloric acid vapors is also obtained from tinplate waste , which contains three to five percent tin.

Tin (II) chloride is sold as a solid salt mass or in solution with excess hydrochloric acid. It is colorless, tastes unpleasantly metallic, gets moist in the air, melts at 40 ° C, becomes completely or almost anhydrous at 100 ° C and forms oxide chloride when heated quickly to 100 ° C, from which tin (II) is anhydrous at higher temperatures. chloride distilled off.

It dissolves easily in ethanol and in a little water, gives an acid chloride and insoluble, white, basic tin (II) chloride with more water and a clear solution only in the presence of hydrochloric acid, tartaric acid or ammonia . The crystals and the solution absorb oxygen in the air with the formation of insoluble, white oxychloride, which is reduced again in the presence of hydrochloric acid and tin.

properties

Tin (II) chloride

In the pure state, crystalline tin (II) chloride melts at 246 ° C. The monoclinic tin (II) chloride dihydrate melts at 40 ° C and evaporates at a higher temperature with decomposition. It shows a blue fluorescence under UV light .

Tin shavings dissolve in warm hydrochloric acid and the solution gives off large, transparent crystals of tin (II) chloride dihydrate when it evaporates. This tin salt is produced on an industrial scale by dissolving tin in hydrochloric acid, whereby the metal must always be present in excess, since the solution evaporates up to 75 or 78 ° C in the presence of some granulated tin and causes the salt to crystallize.

Tin (II) chloride is a powerful reducing agent . Silver and mercury salts are reduced to metals. Furthermore, it can reduce iron (III) salts to iron (II) salts or chromates to chromium (III) salts.

Since tin (II) ions are amphoteric , tin hydroxychloride (basic tin chloride) can form in alkaline to slightly acidic solutions:

{\ displaystyle \ mathrm {SnCl_ {2} + H_ {2} O \ longrightarrow Sn (OH) Cl + HCl}}

The so-called basic tin chloride is hardly soluble in water. This reaction is the reason why aqueous tin chloride solutions become cloudy. By a slight acidification z. B. with hydrochloric acid or tartaric acid, the precipitation of the hydroxychloride can be prevented.

Oxidation to tin (IV) chloride takes place easily in aqueous or hydrochloric acid solution by atmospheric oxygen . The acidic conditions prevent the basic tin salt from precipitating:

{\ displaystyle \ mathrm {2 \ SnCl_ {2} + O_ {2} +4 \ HCl \ longrightarrow 2 \ SnCl_ {4} +2 \ H_ {2} O}}

use

Tin (II) chloride is used as a reducing agent in the laboratory . In electroplating , it is used for electrolytic tinning .

Tin (II) chloride is used in chemical analysis, in dyeing to reduce indigo and iron and manganese oxide on witnesses, as a pickling agent , namely for dyeing with cochineal , for brightening and rosing, also for the representation of gold purple and lacquer colors , as antichloro and for removing rust stains from laundry.

Tin (II) chloride, which is dissolved in concentrated hydrochloric acid , is used as a detection agent for arsenic in the Bettendorf sample . The solution turns brown, as tin (II) chloride reduces the arsenic compound and elemental arsenic is precipitated. The only disturbing elements are mercury and precious metals. This reagent can also be used to detect sesame oil , as the solution turns red when layered with sesame oil.

{\ displaystyle \ mathrm {As_ {2} O_ {3} +3 \ SnCl_ {2} +6 \ HCl \ longrightarrow 2 \ As + 3 \ SnCl_ {4} +3 \ H_ {2} O}}

In food technology it is used as an antioxidant , acidifier and stabilizer , whereby it prevents discoloration of white canned vegetables (e.g. asparagus ). In the EU , it is approved as a food additive with the number E 512 only for canned asparagus in jars or cans with a maximum quantity restriction of 25 mg / kg for the tin content in the end product. In the usual amounts it is considered to be harmless to health, but stomach irritation is possible in large amounts.

In some toothpastes, it is also said to serve as enamel protection

Web links

Video: Bettendorf's arsenic detection in an experiment with explanation

Individual evidence

↑ Entry on STANNOUS CHLORIDE in the CosIng database of the EU Commission, accessed on February 10, 2020.

↑ Entry on E 512: Stannous chloride in the European database for food additives, accessed on August 6, 2020.

↑ ^a ^b Entry on tin chlorides. In: Römpp Online . Georg Thieme Verlag, accessed on May 26, 2014.

↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on tin (II) chloride in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .

↑ T. Seilnacht: tin (II) chloride

^ J. Strähle, E. Schweda: Jander · Blasius - Introduction to the inorganic-chemical practical course. 14th edition. Hirzel, Stuttgart 1995, ISBN 978-3-77-760672-9 , p. 262.

^ Entry on Bettendorf test. In: Römpp Online . Georg Thieme Verlag, accessed on October 12, 2012.

↑ Zusatzstoffe-online.de: Tin (II) chloride

↑ Ingredients of the Elmex enamel protection paste: Stannous Chloride

[CosIng-1] Entry on STANNOUS CHLORIDE in the CosIng database of the EU Commission, accessed on February 10, 2020.

[E-Nummer512-2] Entry on E 512: Stannous chloride in the European database for food additives, accessed on August 6, 2020.

[roempp-3] Entry on tin chlorides. In: Römpp Online . Georg Thieme Verlag, accessed on May 26, 2014.

[GESTIS-4] ↑ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ Entry on tin (II) chloride in the GESTIS substance database of the IFA , accessed on January 8, 2020(JavaScript required) .

[5] T. Seilnacht: tin (II) chloride

[6] J. Strähle, E. Schweda: Jander · Blasius - Introduction to the inorganic-chemical practical course. 14th edition. Hirzel, Stuttgart 1995, ISBN 978-3-77-760672-9 , p. 262.

[7] Entry on Bettendorf test. In: Römpp Online . Georg Thieme Verlag, accessed on October 12, 2012.

[8] Zusatzstoffe-online.de: Tin (II) chloride