Potassium ferrocyanide
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potassium ferrocyanide
(pə′tas·ē·əm ′fer·ō′sī·ə′nīd)
(inorganic chemistry) K4Fe(CN)6·3H2O Yellow crystals with saline taste; soluble in water, insoluble in alcohol; loses water at 60°C; used in medicine, dry colors, explosives, and as an analytical reagent. Also known as yellow prussiate of potash.
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Potassium ferrocyanide
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Potassium ferrocyanide
| Potassium ferrocyanide | |
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Potassium hexacyanidoferrate(II) |
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Other names
Potassium hexacyanoferrate (II), trihydrate; Tetrapotassium ferrocyanide, trihydrate; Ferrate (4-), hexacyano, tetrapotassium, trihydrate [1] |
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| Identifiers | |
| CAS number | 13943-58-3  , (anhydrous)14459-95-1 (trihydrate) |
| PubChem | 161067 |
| Properties | |
| Molecular formula | C6N6FeK4 |
| Molar mass | 368.35 g/mol (anhydrous) 422.388 g/mol (trihydrate) |
| Appearance | Light yellow, crystalline granules. |
| Density | 1.85 g/cm3 (trihydrate) |
| Melting point |
69−71 °C |
| Boiling point |
400 °C (decomp) |
| Solubility in water | trihydrate 28.9 g/100 mL (20 °C) |
| Solubility | insoluble in ethanol, ether |
| Hazards | |
| EU Index | Not listed |
| R-phrases | R32, R52, R53 |
| S-phrases | S50(B), S61 |
| NFPA 704 |
 0
1
0
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| Flash point | Non-flammable |
| Related compounds | |
| Other anions | Potassium ferricyanide |
| Other cations | Sodium ferrocyanide Prussian blue |
 (verify) (what is:  / ?)Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) |
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| Infobox references | |
Potassium ferrocyanide is the inorganic compound with formula K4[Fe(CN)6] · 3H2O. It is the potassium salt of the coordination complex [Fe(CN)6]4-. This salt forms lemon-yellow monoclinic crystals.
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Contents
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Synthesis
Potassium ferrocyanide is produced industrially from hydrogen cyanide, ferrous chloride, calcium hydroxide, the combination of which affords Ca2[Fe(CN)6] · 11H2O. This solution is then treated with potassium salts to precipitate the mixed calcium-potassium salt CaK2[Fe(CN)6], which in turn is treated with potassium carbonate to give the tetrapotassium salt.[2]
Chemical reactions
Treatment of potassium ferrocyanide with nitric acid givesH2[Fe(NO)(CN)5]. After neutralization of this intermediate with sodium carbonate, red crystals of sodium nitroprusside can be selectively crystallized.[3]
Upon treatment with chlorine gas, potassium ferrocyanide converts to potassium ferricyanide:
- 2 K4[Fe(CN)6] + Cl2 → 2 K3[Fe(CN)6] + 2 KCl
This reaction can be used to remove potassium ferrocyanide from a solution.[citation needed]
A famous reaction involves treatment with ferric salts to give Prussian blue. With the approximate composition KFe2(CN)6, this insoluble but deeply coloured material is the blue of blueprinting.
Potassium ferrocyanide, potassium ferricyanide, and Prussian blue account for over 97% of cyanides in the environment.[4]
Applications
Potassium ferrocyanide finds many niche applications in industry. It and the related sodium salt are widely used as anti-caking agents for both road salt and table salt. The potassium and sodium ferrocyanides are also used in the purification of tin and the separation of copper from molybdenum ores. Potassium ferrocyanide is used in the production of wine and citric acid.[2]
In the laboratory, potassium ferrocyanide is used to determine the concentration of potassium permanganate, a compound often used in titrations based on redoxreactions. Potassium ferrocyanide is used in a mixture with potassium ferricyanide and phosphate buffered solution (PBS) to provide a buffer for X-Gal, which is used to cleave Beta-galactosidase, giving a bright blue visualization where an antibody (or other molecule), conjugated to Beta-gal, has bonded to its target.
Potassium ferrocyanide can be used as a fertilizer for plants.[citation needed]
Toxicity
Potassium ferrocyanide is nontoxic, although upon contact with strong acid it can release toxic hydrogen cyanide gas. It is not decomposed to cyanide in the body. The toxicity in rats is low, with lethal dose (LD50) at 6400 mg/kg.[1]
See also
References
- ^ a b "POTASSIUM FERROCYANIDE MSDS Number: P5763 - Effective Date: 12/08/96". J. T. Baker Inc.. http://hazard.com/msds/mf/baker/baker/files/p5763.htm. Retrieved 2012-04-08.
- ^ a b Gail, E.; Gos, S.; Kulzer, R.; Lorösch, J.; Rubo, A.; Sauer, M.; Kellens, R.; Reddy, J.; Steier, N.; Hasenpusch, W. (October 2011). "Cyano Compounds, Inorganic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a08_159.pub3.
- ^ Seel, F. (1965). "Sodium Nitrosyl Cyanoferrate". In Brauer, G.. Handbook of Preparative Inorganic Chemistry. 2 (2nd ed.). New York: Academic Press. p. 1768. LCCN 63-14307. http://www.scribd.com/doc/27443280/Handbook-of-Preparative-Inorganic-Chemistry-Vol-2-2d-Ed-George-Brauer.
- ^ Yu, X. Z.; Gu, J. D.; Li, T. P. (August 2008). "Availability of ferrocyanide and ferricyanide complexes as a nitrogen source to cyanogenic plants". Archives of Environmental Contamination and Toxicology 55 (2): 229–237. doi:10.1007/s00244-007-9101-6. PMID 18180862.
External links
- "Cyanide (inorganic) compounds fact sheet". National Pollutant Inventory Australia. http://www.npi.gov.au/substances/cyanide/index.html.
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