Potassium ferricyanide
- Potassium hexacyanoferrate ( III)
- Potassium ferricyanide
- Ferricyanide
- Red prussiate of potash
- Rotkali
Ruby-red, monoclinic crystals
Fixed
1.85 g · cm -3
Decomposition above 300 ° C.
- Well in water ( 464 g · l-1 at 20 ° C)
- Poorly in ethanol
2970 mg · kg -1 ( LD50, rat, oral)
Template: Infobox chemical / molecular formula search available
Kaliumhexacyanidoferrat (III) is a salt with the formula unit, K3 [Fe (CN ) 6]. It is also referred to as potassium ferricyanide, potassium ferricyanide, potassium ferricyanide, or Rotkali; older nomenclature according to the IUPAC also as potassium hexacyanoferrate ( III). The aqueous solution having a yellow color and decomposes in the light to form iron (III ) hydroxide (Fe (OH ) 3).
Origin of the name
The name of prussiate of potash comes from the presentation by alchemists. They heated blood with bone, horn and other proteinaceous substances in the presence of potash. The residue was leached with water. It then crystallized from a salt which depending on how much air is allowed when heated, red ( red prussiate of potash ) or yellow ( yellow prussiate of potash ) was.
Production
The preparation is carried out by oxidation of Kaliumhexacyanidoferrat (II) (K4 [Fe (CN ) 6] ), with hydrogen peroxide (H2O2) or electrochemically.
Use
The salt is used as a mild oxidizing agent in organic synthesis. In the analysis, it is used for the detection of iron ( II) ions. Here, the so-called Prussian blue is formed.
Cyanotypes are made with Kaliumhexacyanidoferrat (III). Moreover, it is in the dye, used as Stahlhärtungsmittel than wood stain and in photography, for example, as part of the Farmer 's attenuator.
Improper handling may at Kaliumhexacyanidoferrat (III ) by various reactions, the highly toxic prussic acid ( hydrogen cyanide ) form. This danger is particularly given in reactions with strong acids under heat. Even when in contact with strong acids in the cold can be freely hydrocyanic acid under unfavorable circumstances because Kaliumhexacyanidoferrat (III ) as opposed to Kaliumhexacyanidoferrat (II ) shows a weak ligand exchange of water and cyanide.