Question

Prussian blue has two types of iron with oxidation number as shown $\mathop {{\text{Fe}}}\limits^{{\text{III}}} \left[ {\mathop {{\text{Fe}}}\limits^{{\text{II}}} {{\left( {{\text{CN}}} \right)}_{\text{6}}}} \right]$
Net charge on Prussian blue is –x
The value of x is ____

Answer 1

To answer this question, you must recall the structure of the given coordination compound. Coordination compounds are a kind of additional compounds that do not lose their identity in aqueous solution. The net charge can be calculated by adding the oxidation states of each of the metals and ligands present.

Complete step by step solution
We know that coordination compounds are those compounds which contain a central metal atom bonded to a number of other species that may be ionic or neutral molecules carrying a lone pair of electrons. These species are known as ligands. The ligands are bonded to the central metal atom by coordination bond or a dative bond. The lone pair on the ligand is coordinated into the empty d- orbital of the central metal atom or ion.
We are given the compound Prussian blue. Iron in the given coordination compound is present in two different oxidation states. In the coordination sphere, iron is present as ferrous ion $\left( {{\text{F}}{{\text{e}}^{2 + }}} \right)$ with the oxidation state $+ 2$ and outside the coordination sphere, iron is present as ferric ion $\left( {{\text{F}}{{\text{e}}^{3 + }}} \right)$ having oxidation state $+ 3$ . Also there are six cyanide ions present in the coordination sphere and each carries a single negative charge.
So the net charge on the compound can be calculated as $= + 3 + 2 + 6 \times \left( { - 1} \right) = - 1$
Thus, we can say that ${\text{x}} = 1$.

Note
Prussian blue has the chemical formula ${\text{F}}{{\text{e}}_{\text{4}}}{\left[ {{\text{Fe}}{{\left( {{\text{CN}}} \right)}_{\text{6}}}} \right]_{\text{3}}}$ . It is commonly known as Berlin blue or Paris blue. Its systematic name according to the IUPAC nomenclature of coordination compounds is Iron (II, III) Hexacyanoferrate (II, III). It is a commonly used compound in various fields. In medication, it is used as an orally directed antitoxin against metal harming caused by radioactive metals like Thallium and isotopes of Caesium.