Difference Between Potassium Ferrocyanide and Potassium Ferricyanide

The key difference between potassium ferrocyanide and potassium ferricyanide is that potassium ferrocyanide has Fe atom with +2 oxidation state while potassium ferricyanide has Fe atom with +3 oxidation state.

Potassium ferrocyanide and potassium ferricyanide are coordination complexes of iron (Fe) where potassium is the cation and iron-cyanide complex is the anion.

CONTENTS

1. Overview and Key Difference
2. What is Potassium Ferrocyanide
3. What is Potassium Ferricyanide
4. Side by Side Comparison – Potassium Ferrocyanide vs Potassium Ferricyanide in Tabular Form
5. Summary

What is Potassium Ferrocyanide?

Potassium ferrocyanide is an inorganic compound having the chemical formula K4[Fe(CN)6].3H2O. This compound can be identified as the potassium salt of the ferrocyanide coordination complex. Therefore, potassium is the cation in this complex while iron-cyanide complex is the anion. This substance occurs as monoclinic crystals having a lemon-yellow color.

The modern production method for potassium ferrocyanide includes the industrial technique, which involves the chemical compounds HCl, FeCl2, and Ca(OH)2. The combination of these chemical substances forms a solution which is then treated with potassium salt in order to get the precipitated form of calcium-potassium salt having the chemical formula CaK2[Fe(CN)6].11H2O. Thereafter, we need to treat this resulting solution with potassium carbonate in order to get the tetrapotassium salt.

There are different important uses of potassium ferrocyanide, including the use of this compound as anticaking agents for both road salt and table salt, in the purification of tin and the separation of copper from molybdenum ores, in the production of wine and citric acid, etc.

Potassium ferrocyanide compound can be recognized as a non-toxic compound which does not decompose to form cyanide in the body. In experimental procedures, this compound shows very low toxicity in rats having a lethal dose, L50 of 6400 mg/kg.

What is Potassium Ferricyanide?

Potassium ferricyanide is an inorganic compound having the chemical formula K3[Fe(CN)6]. It is a bright red colored salt that contains an octahedrally coordinated iron-cyanide complex anion. This substance is water-soluble, and after dissolving in water, it forms a solution having a green-yellow fluorescence.

We can prepare potassium ferricyanide via passing chlorine gas through a solution of potassium ferrocyanide. Here, potassium ferricyanide separates from the solution. The crystals of this compound have a monoclinic crystal system. The coordination geometry around the Fe atom is octahedral.

There are important applications of potassium ferricyanide; it is mainly used in blueprint drawing and in photography, used as an oxidizing agent to remove silver from color negatives and positives during the bleaching processes, used to harden iron and steel, useful in electroplating, manufacture of dyeing wool, as a laboratory reagent, etc.

What is the Difference Between Potassium Ferrocyanide and Potassium Ferricyanide?

Potassium ferrocyanide and potassium ferricyanide are important inorganic compounds. These are potassium salts of iron-cyanide coordination complexes. The key difference between potassium ferrocyanide and potassium ferricyanide is that potassium ferrocyanide has Fe atom with +2 oxidation state while potassium ferricyanide has Fe atom with +3 oxidation state. Furthermore, an easily distinguishable difference between potassium ferrocyanide and potassium ferricyanide is that the potassium ferrocyanide occurs as lemon-yellow colored crystals, while potassium ferricyanide occurs as bright red crystals.

Moreover, potassium ferrocyanide is considered as a nontoxic compound whereas, potassium ferricyanide has a low toxicity and can be an irritant to eyes and skin.

Below tabulation provides a summary of the difference between potassium ferrocyanide and potassium ferricyanide.

Summary – Potassium Ferrocyanide vs Potassium Ferricyanide

Potassium ferrocyanide and potassium ferricyanide are important inorganic compounds. These are potassium salts of iron-cyanide coordination complexes. The key difference between potassium ferrocyanide and potassium ferricyanide is that potassium ferrocyanide has Fe atom with +2 oxidation state while potassium ferricyanide has Fe atom with +3 oxidation state.

Reference:

1. “Potassium Ferrocyanide.” ScienceDirect, Available here.

Image Courtesy:

1. “Potassium ferrocyanide” By Wilco Oelen –  (CC BY-SA 3.0) via Commons Wikimedia
2. “Potassium-ferricyanide-sample” By Benjah-bmm27 – Own work (Public Domain) via Commons Wikimedia