Q. Both ${Co}^{3 +}\ and\ {Pt}^{4 +}$have a coordination number of six. Which of the following pairs of complexes will show approximately the same electrical conductance for their 0.001 M aqueous solutions?
A) ${CoCl}_{2}.4{NH}_{3}\ and\ {PtCl}_{4}\ .4{NH}_{3}$
B) ${CoCl}_{3}.3{NH}_{3}\ and\ {PtCl}_{4}\ .5{NH}_{3}$
C) ${CoCl}_{3}.6{NH}_{3}\ and\ {PtCl}_{4}\ .5{NH}_{3}$
D) ${CoCl}_{3}.6{NH}_{3}\ and\ {PtCl}_{4}\ .3{NH}_{3}$
Explanation
(c)
${Co}^{3 +}\ and\ {Pt}^{4 +}$ have 6 coordination number.
${CoCl}_{3}.6{NH}_{3}\ and\ {PtCl}_{4}.5{NH}_{3}$
$\lbrack Co\left( {NH}_{3} \right)_{6}{Cl}_{3}\overset{In\ solution}{\rightarrow}\left\lbrack Co\left( {NH}_{3} \right)_{6} \right\rbrack^{3 +} + 3{Cl}^{-}$
$\lbrack PtCl\left( {NH}_{3} \right)_{5}{Cl}_{3}\overset{In\ solution}{\rightarrow}\ \ \ \left\lbrack PtCl\left( {NH}_{3} \right)_{5} \right\rbrack^{3 +} + 3{Cl}^{-}$
Number of ionic species are same in the solution of both complexes, therefore their equimolar solutions will show same conductance.
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.