Question

A Complex of $PtC{l_4}.5N{H_3}$ shows a molar conductance of $402\; ohm^{-1}cm^{-1}mol^{-1}$ in water and precipitates three moles of $AgCl$ with $AgN{O_3}$ solution. The formula of the complex is:
A. $[Pt(NH_3)_6]Cl_4$
B. $[Pt{(N{H_3})_6}Cl_2]C{l_2}$
C. $[Pt{(N{H_3})_5}Cl]C{l_3}$
D. $[Pt{(N{H_3})_3}Cl_3]Cl$

Answer 1

Hint: A complex $PtC{l_4}.5N{H_3}$ gets precipitated with $AgCl$. The three moles which are produced are from the $3C{l^ - }$ ions when reacted with $AgN{O_3}$.

Complete step by step answer:
A precipitation reaction is a reaction in which two soluble salts are combined forming one insoluble salts. This insoluble salt is known as a precipitate. Precipitation reaction helps us to determine the presence of various ions in a solution.
The $PtC{l_4}.5N{H_3}$ is a complex compound for which the chemical and structural formula was given by Werner’s coordination complex Theory.
Molar Conductivity of a compound is the conducting power of all the ions produced when one mole of an electrolyte is dissolved in a solution. It is denoted by $\lambda (lambda)$.
The reaction is as below:
$[Pt{(N{H_3})_5}Cl]C{l_3}$ $ + AgN{O_3}$ \[\rightarrow \; {[Pt{(N{H_3})_5}Cl]^{3 + }} + 3C{l^ - }\]
The electrical conductivity of aqueous solutions of this compound is proportional to the number of ions formed per mole when it is dissolved in an aqueous solution. The three moles of$AgCl$ during precipitation with silver nitrate gives three free chloride ions.
Therefore the correct coordination complex is $[Pt{(N{H_3})_5}Cl]C{l_3}$.

The correct answer is Option(C).

Note:
The complex $[Pt{(N{H_3})_5}Cl]C{l_3}$ is the coordination complex for which the coordination number of the metal is 4. According to Werner theory, this complex can exists in two isomeric forms, cis and trans. The complex has the four ligands attached to the metal giving it a tetrahedral structure which lies in the same plane. Therefore, the complex is either square planar or tetrahedral in nature.