K4Fe(CN)6 - Potassium Ferrocyanide

What is Potassium Ferrocyanide?

Potassium ferrocyanide is an inorganic compound with the chemical formula K4Fe(CN)6. Potassium ferrocyanide is also known as yellow potash prussiate, a yellow crystal. It was made with wool or horn clippings stirring hot potassium carbonate with an iron rod. Potassium ferrocyanide was used for certain iron processes as a developer and as an additive for developers of alkaline pyro.

Other names – yellow prussiate of potash, potassium hexacyanoferrate (II)

K4Fe(CN)6 Potassium ferrocyanide
Density 1.85 g/cm³
Molecular Weight/ Molar Mass 368.35 g/mol
Boiling Point 400 °C
Melting Point 300 °C
Chemical Formula K4Fe(CN)6

Potassium Ferrocyanide Structure – K4Fe(CN)6


Potassium Ferrocyanide Structure

Physical Properties of Potassium Ferrocyanide – K4Fe(CN)6

Odour No odour
Appearance Light yellow, crystalline granules
Covalently-Bonded Unit 10
Hydrogen Bond Acceptor 12
Complexity 127
Solubility Insoluble in ethanol, ether

Chemical Properties of Potassium Ferrocyanide – K4Fe(CN)6

    • Potassium ferrocyanide reacts with sulphuric acid in aqueous medium forms potassium sulfate, ferrous sulfate, ammonium sulfate and carbon monoxide.

K4[Fe(CN)6] + 6H2SO4 + 6H2O → 2K2SO4 + FeSO4 + 3(NH4)2SO4 + 6CO

    • Potassium ferrocyanide reacts with ferric chloride forms a complex compound Iron (III) potassium hexacyanidoferrate(II) and potassium chloride.

K4[Fe(CN)6] + FeCl3 → KFe[Fe(CN)6] + 3 KCl

Uses of Potassium Ferrocyanide – K4Fe(CN)6

  • Used in the tempering of steel and in process engraving. It is employed in the manufacture of pigments and as a chemical reagent.
  • A small amount in pyro and hydroquinone developers tends to lower fog and give greater density.
  • Used in the manufacture of potassium cyanide, which is used extensively in gold mining.
  • Ferro Cyanogen forms with most metal compounds insoluble in water some of which exhibit highly characteristic colours. It serves as a test for cupric and ferric compounds.

Frequently Asked Questions

What are the uses of potassium ferrocyanide?

Potassium ferrocyanide has many niche uses in industry. It and the related sodium salt (sodium ferrocyanide) are commonly used for both road salt and table salt as anti creating agents. Also, potassium and sodium ferrocyanides are used to purify tin and isolate copper from molybdenum ores. Potassium ferrocyanide is also used for wine and citric acid production.

Is potassium ferrocyanide toxic?

Potassium ferrocyanide is not toxic to humans since it is not decomposed to cyanide in the body. However, if mixed with strong acids, this compound can be potentially fatal.

How can potassium ferricyanide be prepared from potassium ferrocyanide?

A 100 g potassium ferrocyanide solution in 1000 ml water must be saturated with chlorine, and stirred regularly, until the solution shows a fine, deep red colour.

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