Tin dichloride
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| Names | |
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IUPAC names
Tin(II) chloride
Tin dichloride |
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| Other names
Stannous chloride
Tin salt Tin protochloride |
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| Identifiers | |
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3D model (JSmol)
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| ChEBI | |
| ChemSpider | |
| ECHA InfoCard | 100.133.348 |
| E number | E512 (acidity regulators, ...) |
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PubChem CID
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| RTECS number | XP8700000 (anhydrous) XP8850000 (dihydrate) |
| UN number | 3260 |
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| Properties | |
| SnCl2 | |
| Molar mass | 189.60 g/mol (anhydrous) 225.63 g/mol (dihydrate) |
| Appearance | White crystalline solid |
| Odor | odorless |
| Density | 3.95 g/cm3 (anhydrous) 2.71 g/cm3 (dihydrate) |
| Melting point | 247 °C (477 °F; 520 K) (anhydrous) 37.7 °C (dihydrate) |
| Boiling point | 623 °C (1,153 °F; 896 K) (decomposes) |
| 83.9 g/100 ml (0 °C) Hydrolyses in hot water |
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| Solubility | soluble in ethanol, acetone, ether, Tetrahydrofuran insoluble in xylene |
| −69.0·10−6 cm3/mol | |
| Structure | |
| Layer structure (chains of SnCl3 groups) |
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Trigonal pyramidal (anhydrous) Dihydrate also three-coordinate |
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| Bent (gas phase) | |
| Hazards | |
| Main hazards | Irritant, dangerous for aquatic organisms |
| Safety data sheet |
See: data page ICSC 0955 (anhydrous) ICSC 0783 (dihydrate) |
| NFPA 704 | |
| Lethal dose or concentration (LD, LC): | |
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LD50 (median dose)
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700 mg/kg (rat, oral) 10,000 mg/kg (rabbit, oral) 250 mg/kg (mouse, oral) |
| Related compounds | |
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Other anions
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Tin(II) fluoride Tin(II) bromide Tin(II) iodide |
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Other cations
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Germanium dichloride Tin(IV) chloride Lead(II) chloride |
| Supplementary data page | |
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Refractive index (n), Dielectric constant (εr), etc. |
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Thermodynamic
data |
Phase behaviour solid–liquid–gas |
| UV, IR, NMR, MS | |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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 (what is   ?) |
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| Infobox references | |
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.
Tin(II) chloride can dissolve in less than its own mass of water without apparent decomposition, but as the solution is diluted hydrolysis occurs to form an insoluble basic salt:
Therefore, if clear solutions of tin(II) chloride are to be used, it must be dissolved in hydrochloric acid (typically of the same or greater molarity as the stannous chloride) to maintain the equilibrium towards the left-hand side (using Le Chatelier's principle). Solutions of SnCl2 are also unstable towards oxidation by the air:
This can be prevented by storing the solution over lumps of tin metal.
There are many such cases where tin(II) chloride acts as a reducing agent, reducing silver and gold salts to the metal, and iron(III) salts to iron(II), for example:
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