Potassium ferricyanide - wikipedia Potassium ferricyanide Not to be confused with potassium ferrocyanide. Potassium ferricyanide Names IUPAC name Potassium hexacyanoferrate ( III ) Other names Red prussiate of Potash, Prussian red, Potassium ferricyanide Identifiers CAS Number 13746 - 66 - 2 3D model ( JSmol ) Interactive image ChemSpider 24458 ECHA InfoCard 100.033. 916 PubChem CID 26250 RTECS number LJ8225000 InChI InChI = 1S / 6CN. Fe. 3K / c6 * 1 - 2 ; ; ; ; / q6 * - 1 ; + 3 ; 3 * + 1 Key : BYGOPQKDHGXNCD - UHFFFAOYSA - N InChI = 1S / 6CN. Fe. 3K / c6 * 1 - 2 ; ; ; ; / q6 * - 1 ; + 3 ; 3 * + 1 Key : BYGOPQKDHGXNCD - UHFFFAOYAG SMILES ( C - ) # N. ( C - ) # N. ( C - ) # N. ( C - ) # N. ( C - ) # N. ( C - ) # N. ( K+ ). ( K+ ). ( K+ ). ( Fe + 3 ) Properties Chemical formula K ( Fe ( CN ) ) Molar mass 329.24 g / mol Appearance deep red crystals, sometimes small pellets, orange to dark red powder Density 1.89 g / cm, solid Melting point 300 ° C ( 572 ° F ; 573 K ) Boiling point decomposes Solubility in water 330 g / L ( `` cold water '' ) 464 g / L ( 20 ° C ) 775 g / L ( `` hot water '' ) Solubility slightly soluble in alcohol soluble in acid soluble in water Magnetic susceptibility ( χ ) + 2290.0 10 cm / mol Structure Crystal structure monoclinic Coordination geometry octahedral at Fe Hazards Safety data sheet MSDS R - phrases ( outdated ) R20, R21, R22, R32 S - phrases ( outdated ) S26, S36 NFPA 704 0 0 Flash point Non-flammable Related compounds Other anions Potassium ferrocyanide Other cations Prussian blue Except where otherwise noted, data are given for materials in their standard state ( at 25 ° C ( 77 ° F ), 100 kPa ). N verify ( what is ? ) Infobox references Potassium ferricyanide is the chemical compound with the formula K ( Fe ( CN ) ). This bright red salt contains the octahedrally coordinated ( Fe ( CN ) ) ion. It is soluble in water and its solution shows some green - yellow fluorescence. It was discovered in 1822 by Leopold Gmelin, and was initially used in the production of ultramarine dyes. Contents 1 Preparation 2 Structure 3 Applications 4 Prussian blue 5 Safety 6 See also 7 References 8 External links Preparation Potassium ferricyanide is manufactured by passing chlorine through a solution of potassium ferrocyanide. Potassium ferricyanide separates from the solution : 2 K ( Fe ( CN ) ) + Cl → 2 K ( Fe ( CN ) ) + 2 KCl Structure Like other metal cyanides, solid potassium ferricyanide has a complicated polymeric structure. The polymer consists of octahedral ( Fe ( CN ) ) centers crosslinked with K ions that are bound to the CN ligands. The K -- - NCFe linkages break when the solid is dissolved in water. Applications The compound has widespread use in blueprint drawing and in photography ( Cyanotype process ). Several photographic print toning processes involve the use of potassium ferricyanide. Potassium ferricyanide was used as an oxidizing agent to remove silver from color negatives and positives during processing, a process called bleaching. Because potassium ferricyanide bleaches are environmentally unfriendly, short - lived and capable of releasing cyanide gas if mixed with acid, bleaches using ferric EDTA have been used in color processing since the 1972 introduction of the Kodak C - 41 process. In color lithography, potassium ferricyanide is used to reduce the size of color dots without reducing their number, as a kind of manual color correction called dot etching. It is also used in black - and - white photography with sodium thiosulfate ( hypo ) to reduce the density of a negative or gelatin silver print where the mixture is known as Farmer 's reducer ; this can help offset problems from overexposure of the negative, or brighten the highlights in the print. The compound is also used to harden iron and steel, in electroplating, dyeing wool, as a laboratory reagent, and as a mild oxidizing agent in organic chemistry. Potassium ferricyanide is also one of two compounds present in ferroxyl indicator solution ( along with phenolphthalein ) which turns blue ( Prussian blue ) in the presence of Fe ions, and which can therefore be used to detect metal oxidation that will lead to rust. It is possible to calculate the number of moles of Fe ions by using a colorimeter, because of the very intense color of Prussian blue Fe ( Fe ( CN ) ). Potassium ferricyanide is often used in physiology experiments as a means of increasing a solution 's redox potential ( E ° ' ~ 436 mV at pH 7 ). As such, it can oxidize reduced cytochrome c ( E ° ' ~ 247 mV at pH 7 ) in intact isolated mitochondria. Sodium dithionite is usually used as a reducing chemical in such experiments ( E ° ' ~ − 420 mV at pH 7 ). Potassium ferricyanide is used in many amperometric biosensors as an electron transfer agent replacing an enzyme 's natural electron transfer agent such as oxygen as with the enzyme glucose oxidase. It is used as this ingredient in many commercially available blood glucose meters for use by diabetics. Potassium ferricyanide is combined with potassium hydroxide ( or sodium hydroxide as a substitute ) and water to formulate Murakami 's etchant. This etchant is used by metallographers to provide contrast between binder and carbide phases in cemented carbides. Prussian blue Prussian blue, the deep blue pigment in blue printing, is generated by the reaction of K ( Fe ( CN ) ) with ferrous ( Fe ) ions as well as K ( Fe ( CN ) ) with ferric salts. In histology, potassium ferricyanide is used to detect ferrous iron in biological tissue. Potassium ferricyanide reacts with ferrous iron in acidic solution to produce the insoluble blue pigment, commonly referred to as Turnbull 's blue or Prussian blue. To detect ferric ( Fe ) iron, potassium ferrocyanide is used instead in the Perls ' Prussian blue staining method. The material formed in the Turnbull 's blue reaction and the compound formed in the Prussian blue reaction are the same. Safety Potassium ferricyanide has low toxicity, its main hazard being that it is a mild irritant to the eyes and skin. However, under very strongly acidic conditions, highly toxic hydrogen cyanide gas is evolved, according to the equation : 6 H + ( Fe ( CN ) ) → 6 HCN + Fe The reaction with hydrochloric acid is as follows : 6 HCl + K ( Fe ( CN ) ) → 6 HCN + FeCl + 3 KCl See also Ferricyanide Ferrocyanide Potassium ferrocyanide References Jump up ^ Kwong, H. - L. ( 2004 ). `` Potassium Ferricyanide ''. In Paquette, L. Encyclopedia of Reagents for Organic Synthesis. New York : J. Wiley & Sons. doi : 10.1002 / 047084289. Jump up ^ Sharpe, A.G. ( 1976 ). The Chemistry of Cyano Complexes of the Transition Metals. London : Academic Press. Jump up ^ Ihde, A.J. ( 1984 ). The Development of Modern Chemistry ( 2nd ed. ). New York : Dover Publications. p. 153. Jump up ^ Figgis, B.N. ; Gerloch, M. ; Mason, R. `` The crystallography and paramagnetic anisotropy of potassium ferricyanide '' Proceedings of the Royal Society of London, Series A : Mathematical and Physical Sciences 1969, vol. 309, p91 - 118. doi : 10.1098 / rspa. 1969.0031 Jump up ^ Stroebel, L. ; Zakia, R.D. ( 1993 ). `` Farmer 's Reducer ''. The Focal Encyclopedia of Photography. Focal Press. p. 297. ISBN 978 - 0 - 240 - 51417 - 8. Jump up ^ Dunbar, K.R. ; Heintz, R.A. ( 1997 ). `` Chemistry of Transition Metal Cyanide Compounds : Modern Perspectives ''. Progress in Inorganic Chemistry. 45. pp. 283 -- 391. doi : 10.1002 / 9780470166468. ch4. Jump up ^ Carson, F.L. ( 1997 ). Histotechnology : A Self - Instructional Text ( 2nd ed. ). Chicago : American Society of Clinical Pathologists. pp. 209 -- 211. ISBN 0 - 89189 - 411 - X. Jump up ^ Tafesse, F. ( 2003 ). `` Comparative Studies on Prussian Blue or Diaquatetraamine - Cobalt ( III ) Promoted Hydrolysis of 4 - Nitrophenylphosphate in Microemulsions '' ( pdf ). International Journal of Molecular Sciences. 4 ( 6 ) : 362 -- 370. doi : 10.3390 / i4060362. Jump up ^ Verdaguer, M. ; Galvez, N. ; Garde, R. ; Desplanches, C. ( 2002 ). `` Electrons at Work in Prussian Blue Analogues '' ( pdf ). Electrochemical Society Interface. 11 ( 3 ) : 28 -- 32. doi : 10.1002 / chin. 200304218. Jump up ^ `` MSDS for potassium ferricyanide '' ( PDF ). External links International Chemical Safety Card 1132 National Pollutant Inventory -- Cyanide compounds fact sheet Potassium compounds KAsO KBr KBrO KCN KCNO KCl KClO KClO KClO KF KH KHCO KHCO KHF KHS KHSO KHSO KH AsO KH PO KH PO KI KIO KIO KMnO KN KNH KNO KNO KOCN KOH KO KPF KSCN KCH COO K Al O K CO K CrO K Cr O K FeO K HPO K MnO K O K O K PtCl K PtCl K SeO K SO K SO KHSO K S O K S O K S O K Po K SiO K ( Fe ( CN ) ) K ( Fe ( C O ) ) K ( Fe ( CN ) ) K PO K Mo Cl Retrieved from `` https://en.wikipedia.org/w/index.php?title=Potassium_ferricyanide&oldid=833107049 '' Categories : Potassium compounds Iron compounds Cyano complexes Coordination compounds Photographic chemicals Oxidizing agents Hidden categories : Articles without EBI source Articles without KEGG source Articles without UNII source Articles with changed ChemSpider identifier ECHA InfoCard ID from Wikidata Articles with changed InChI identifier Chembox having DSD data Articles containing unverified chemical infoboxes Talk Contents About Wikipedia تۆرکجه Català Čeština Deutsch Ελληνικά Español فارسی Français Italiano Latviešu Magyar Nederlands 日本 語 Polski Português Română Русский Slovenčina Српски / srpski Srpskohrvatski / српскохрватски Svenska Українська Tiếng Việt 中文 16 more Edit links This page was last edited on 29 March 2018, at 18 : 19. 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Question: according to vsepr what is the expected geometry for potassium ferricyanide
Answer: octahedral at Fe