Potassium ferricyanide is a bright red soluble crystalline compound that has many different applications. These applications include photography, electroplating, making dyes and pigments, cyanotyping, use as a laboratory reagent and making light-sensitive paper. Additional uses of potassium ferricyanide include blueprint drawing, iron and copper toning and use as an oxidizing agent. Potassium ferricyanide is also a relatively safe compound to use unless mixed with other chemicals or heated to very high temperatures.
General
Other names for potassium ferricyanide include tripotassium ferricyanide, potassium cyanoferrate, red prussiate, potassium ferricyanate and potassium hexacyanoferrate III. Although potassium ferricyanide is generally a stable compound, this substance is not compatible with strong oxidizing agents, ammonia and many acids. Additionally, exposure to light can discolor potassium ferricyanide. Further, potassium ferricyanide is not soluble in alcohol but will dissolve in water.
Photography
Photographers use potassium ferricyanide to reduce the density of negatives to help compensate for problems with overexposure. Additionally, photographers use potassium ferricyanide as an oxidizing agent in a process called dot etching to remove silver from negatives and positives. In black-and-white photography, potassium ferricyanide acts as a bleaching agent to the highlight areas. On the other hand, in color photography, postassium ferricyanide decreases the size of color dots without reducing the number of dots.
Science
Scientists use potassium ferricyanide to detect ferrous iron in biological tissue. Additionally, when potassium ferricyanide reacts in an acidic solution, it produces an insoluble blue pigment called Turnbull's blue. Futher, scientists use potassium ferricyanide to detect the presence of iron ions and detect metal oxidation that can lead to rust.
Industrial Use
Potassium ferricyanide also has several industrial applications. Manufacturers use potassium ferricyanide to make adhesives, metal extractions, paints, inks, fire retardants, dyes, computer electronics, pharmaceuticals, rocket propellant, plexiglass and cosmetics. Additionally, the food industry uses potassium ferricyanide in low doses in some food preparations. Further, the wine industry uses potassium ferricyanide to remove copper from red wine in cases where the winemakers used copper as a fungicide on the grapes.
References
- "Hazardous Chemicals Desk Reference"; Richard J. Lewis Sr.; 2008
- "The Darkroom Cookbook, Third Edition"; Steve Anchell; 2008
- "Handbook of Chemicals & Gases for the Semi- Conductor Industry"; Ashutosh Misra, Jeremiah D. Hogan and Russell Chorush; 2002
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