Potassium ferrocyanide is defined as an inorganic compound having the chemical formula K4Fe(CN)6 (potassium ferrocyanide formula). Potassium ferrocyanide is otherwise called yellow potash prussiate, which is a yellow crystal. It was made with either horn or wool clippings stirring hot potassium carbonate using an iron rod. Potassium ferrocyanide compound can be used for certain iron processes as a developer and as an additive for alkaline pyro developers.
Potassium hexacyanoferrate (II), yellow prussiate of potash are the other names of Potassium Ferrocyanide.
Potassium Ferrocyanide Structure – K4Fe(CN)6
The structure of Potassium Ferrocyanide can be represented as follows:
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Properties of Potassium Ferrocyanide
Let us look at some of the important properties of potassium ferrocyanide
Physical Properties of Potassium Ferrocyanide – K4Fe(CN)6
Chemical Properties of Potassium Ferrocyanide – K4Fe(CN)6
K4[Fe(CN)6] + 6H2SO4 + 6H2O → 2K2SO4 + FeSO4 + 3(NH4)2SO4 + 6CO
K4[Fe(CN)6] + FeCl3 → KFe[Fe(CN)6] + 3 KCIC
Uses of Potassium Ferrocyanide – K4Fe(CN)6
Potassium Ferrocyanide can be used in steel tempering and the engraving process. It is also employed in pigment manufacture and as a chemical reagent.
A small amount in hydroquinone and pyro developers tends to lower fog and produce greater density.
It is also used in potassium cyanide manufacture, which can be extensively used in gold mining.
Besides, Ferro Cyanogen produces the most metal compounds insoluble in water, where a few of which exhibit highly characteristic colours. It serves as a test for both ferric and cupric compounds.
Applications of Potassium Ferrocyanide
The important applications of Potassium ferrocyanide can be listed as follows:
Potassium ferrocyanide finds several niche applications in the industry. The related sodium salt is widely used as anti-caking agents for both table salt and road salt. The sodium and potassium ferrocyanides can also be used in the separation of copper and from molybdenum ores and purification of tin. Potassium ferrocyanide compound is used in the production of citric acid and wine.
It is also used in animal feeding.
Potassium ferrocyanide is used to determine potassium permanganate concentration in the laboratory, which is a compound often used in titrations according to the redox reactions. Potassium ferrocyanide compound is used in a mixture with the phosphate-buffered solution and potassium ferricyanide to give a buffer for beta-galactosidase. It can be used to cleave X-Gal, producing a bright blue visualization where an antibody (otherwise another molecule), conjugated to the Beta-gal, has bonded to its target. Also, on reacting with Fe(3), it produces a Prussian blue colour. Therefore, it can be used as an identifying reagent for iron in laboratories.
Potassium ferrocyanide compound is used as a plant fertilizer.
Before 1900 AD, prior to the invention of the Castner process, potassium ferrocyanide compound was the essential source of alkali metal cyanides. Potassium cyanide was produced by decomposing potassium ferrocyanide in this historical process. The chemical reaction can be given as follows:
K4[Fe(CN)6] → 4 KCN + FeC2 + N2
Toxicity of Potassium Ferrocyanide on Salt
Acute oral toxicity of the potassium ferrocyanide is given as 5000mg/kg. It means 350gm for a 70kg human. Although the molecules consist of cyanide ions, they are bound more tightly to the iron atom and stay with the iron right through the human digestive system.
The amount that is added to the table salt for anti-caking is of the order of 20 mg/kg of sodium chloride, which means that we would have to eat a truckload of table salt to reach the potassium ferrocyanide’s toxic level. Of course, the salt would kill us long before the potassium ferrocyanide.
Market Availability of Potassium Ferrocyanide
Potassium ferrocyanide compound exists as odourless, light yellow crystals that are soluble in water but insoluble in alcohols. This compound is also referred to as either yellow prussiate of potassium hexacyanoferrate (II) or potash. Potassium ferrocyanide is manufactured from potassium hydroxide and hydrogen ferrocyanide. This compound is not considered to be toxic, but it is dangerous when mixed with other chemicals or heated with them. It can be used commonly for the production of pigments & dyes, steel & iron, pharmaceutical, and many other chemicals, and as a food additive.