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 Fe2+ 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 Fe2+ ions by using a colorimeter, because of the very intense color of Prussian blue Fe4[Fe(CN)6]3.
SAFETY :
Potassium ferricyanide has very 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]3− → 6 HCN + Fe3+[9]
The reaction with hydrochloric acid is as follows:
6 HCl + K3[Fe(CN)6] → 6 HCN + FeCl3 + 3 KCl
IUPAC name : Potassium hexacyanoferrate(III)
Identifiers
CAS number 13746-66-2 Y
PubChem 26250
RTECS number LJ8225000
Properties
Molecular formula C6N6FeK3
Molar mass 329.24 g/mol
Appearance deep red crystals
Density 1.89 g/cm3, solid
Melting point 300 °C, 573 K, 572 °F
Boiling point : decomp.
Solubility in water 330 g/L ("cold water")
464 g/L (20°C)
775 g/L ("hot water")[1]
Solubility slightly soluble in alcohol
soluble in acid
soluble in water