Potassium hexachlorostannate
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| Names | |
|---|---|
| IUPAC name
Potassium hexachlorostannate(IV)
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| Properties | |
| K2SnCl6 | |
| Molar mass | 409.605 g/mol |
| Appearance | White solid |
| Melting point | 300 °C (572 °F; 573 K) (decomposes) |
| Boiling point | Decomposes |
| Soluble | |
| Solubility | Insoluble in 37% HCl |
| Hazards | |
| Safety data sheet | None |
| Flash point | Non-flammable |
| Related compounds | |
| Related compounds
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Ammonium hexachlorostannate |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Potassium hexachlorostannate is an inorganic chemical compound with the chemical formula K2SnCl6, used mainly for obtaining tin(IV) chloride.
Contents
Properties
Chemical
Potassium hexachlorostannate is the salt of a strong acid and its solutions react neutral in water. Addition of alkali or ammonia solution precipitates Sn(OH)4·nH2O. Further addition of strong alkali causes soluble stannate (K2Sn(OH)6) to form.
Physical
Potassium hexachlorostannate is a colorless crystalline solid.
It is insoluble in 37 w% HCl which offers an easy method of purifying the salt.
On strong heating (> 300 °C, est.) it releases SnCl4 (B.P. 114.15 °C), so it affords a chlorine-free route to this useful chemical. The ammonium salt sublimes completely.
Availability
It is not sold by most chemical entities and has to be prepared.
Preparation
Potassium hexachlorostannate (IV) is prepared by dissolving tin metal (or pewter) in a mixture of nitric acid and hydrochloric acid (aqua regia). More or less stoichiometric amounts of the acids can be used in accordance with:
- 3 Sn(s) + 4 NO3-(aq) + 16 H+(aq) → 3 Sn4+(aq) + 4 NO(g) + 8 H2O(l)
- 3 Sn4+(aq) + 18 HCl(aq) → 3 SnCl62-(aq) + 18 H+(aq)
Dissolution is very swift and does not usually require heating.
Once complete the solution is brought to a gentle simmer and solid KCl is added, 2 mol per mol of tin. The mixture is then simmered and stirred until all the KCl is dissolved, then allowed to cool naturally, then further chilled on ice bath, e.g. overnight.
Well-formed crystals of K2SnCl6 are obtained.
Ammonium hexachlorostannate is obtained in identical conditions but by replacing KCl with NH4Cl.
Instead of pure tin, pewter (Sn/Sb alloy) can also be used because the corresponding Sb salt, KSbCl6 is very soluble even at low temperature and simply stays in solution.
The salts can also be obtained by oxidation of an SnCl2 solution in HCl, with hydrogen peroxide or nitric acid as oxidiser. Add KCl (or NH4Cl) as per above.
Projects
- Make tin(IV) chloride
Handling
Safety
Potassium hexachlorostannate may be corrosive and should be handled with proper protection
Storage
In closed containers.
Disposal
Should be disposed like any other tin compound.
