What does ferricyanide mean?
Ferricyanide is a noun denoting a chemical compound that contains the anion Fe(CN)₆³⁻, a hexacyanide complex in which an atom of iron sits in its +3 oxidation state surrounded by six cyanide groups. The most familiar example is potassium ferricyanide, a deep-red crystalline salt widely used in photographic bleaching solutions, blueprint and cyanotype printing, metal finishing, and as an oxidizing agent in analytical chemistry. The name combines 'ferric', referring to trivalent iron, with 'cyanide', reflecting the compound's structural core. Although it contains cyanide groups, ferricyanide is chemically bound within a stable complex and is far less hazardous than free cyanide, though it should never be mixed with strong acids. It is easily confused with ferrocyanide, its divalent-iron counterpart, which differs in oxidation state, electrical charge, and color.
nounA salt or ester of ferricyanic acid containing the trivalent complex anion Fe(CN)₆³⁻, in which iron is in its +3 oxidation state; typically a red crystalline solid.
- A chemical compound containing the Fe(CN)₆³⁻ anion, in which iron has a +3 oxidation state.
"The darkroom technician prepared a solution of potassium ferricyanide to bleach the negative before toning."
"Potassium ferricyanide gives a distinctive deep-red color to its crystals."
"In the presence of light, the film of ferricyanide turned a rich Prussian blue."
Standard plural form used when referring collectively to different ferricyanide compounds or salts.
"Various ferricyanides are employed in industrial and photographic applications."
The blueprint that launched architectural drawing was made with ferricyanide — its photosensitive salts turn brilliant blue under sunlight.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of ferricyanide
The word ferricyanide derives from 'ferric', meaning relating to trivalent iron, itself rooted in the Latin 'ferrum' meaning iron, combined with 'cyanide', which traces back to Greek 'kyanos' for the dark blue pigment derived from the same root that gave cyanogen its name. The term emerged in nineteenth-century chemistry as scientists systematically named the family of iron-cyanogen complexes, distinguishing ferricyanides (iron III) from ferrocyanides (iron II) by their differing oxidation states. Its Latin root also survives in related terms such as ferrous and ferrochrome.
How ferricyanide is actually used
Ferricyanide is primarily a technical term used in chemistry, photography, metallurgy, and laboratory contexts. It rarely appears outside scientific writing, though its best-known salt, potassium ferricyanide, is familiar to photographers and hobbyists through cyanotype printing and blueprint processes. Despite containing cyanide groups, many ferricyanides are relatively stable compounds, though they should still be handled with care.
Easily confused with ferricyanide
Ferrocyanide contains iron in the +2 oxidation state with the anion Fe(CN)₆⁴⁻ and is generally less oxidizing than ferricyanide, which contains trivalent (+3) iron.