Question

What is the IUPAC name of $K_3$$[Fe(CN)_6]$ ?

Answer 1

Hint: This is an inorganic compound. It is the potassium salt of the coordination complex \[{\left[ {Fe{{\left( {CN} \right)}_6}} \right]^{3 - }}\]. During the naming of coordination compounds, additive principle is followed, i.e. name of ligand is added before the name of central metal atom.

Complete step by step answer:
According to the rule of IUPAC, a positive ion whether it is complex or simple is named first followed by the negative ion. The name starts with the small letter.
First, we write potassium then we will do the naming of the complex negative ion.
The complex ion contains two parts.
central metal atom
ligands.
First, we will find the charge on the central metal atom. Since potassium contains +1 charge and 3 potassium are attached with complex ions hence the total charge present on complex ions is -3.
Complex ions contain iron as a central metal atom and there are 6 cyanide ligands atoms. The charge on cyanide atoms is -1 then the total charge on 6 cyanide atoms is -6.
Assume charge on Fe is x. then
  x + ( - 6) = - 3
  x = - 3 + 6
  x = 3
Since cyanide is a negative ligand so during the naming the negative ligand ends in –o.
Hence the IUPAC name of the compound is potassium hexacyanoferrate(iii).

Note:
Another name of this compound is Red prussiate of potash, prussian red, potassium ferricynide.it has deep red crystal appearance. It is soluble in water and acid.