Question

Out of the following complex compounds, which of the compound will be having the minimum conductance in solution?

• A. \([Co(NH_3)_4Cl_2]Cl\)
• B. \([Co(NH_3)_6]Cl_3\)
• C. \([Co(NH_3)_5Cl]Cl\)
• D. \([Co(NH_3)_3Cl_3]\)

Hint:

For complex compounds, the conductance is directly related to the number of ions produced during dissociation. Neutral complexes have the minimum conductance.

Answer 1

The Correct Option is D

Solution conductance is determined by the concentration of ions. Upon dissolution of coordination complexes in water, counter-ions dissociate and contribute to conductance. Ions within the coordination sphere remain undissociated.

Analysis of each complex:

1. $[Co(NH_3)_4Cl_2]Cl$ yields $[Co(NH_3)_4Cl_2]^+$ and $Cl^-$, resulting in 2 ions.

2. $[Co(NH_3)_6]Cl_3$ yields $[Co(NH_3)_6]^{3+}$ and $3Cl^-$, resulting in 4 ions.

3. $[Co(NH_3)_5Cl]Cl_2$ yields $[Co(NH_3)_5Cl]^{2+}$ and $2Cl^-$, resulting in 3 ions.

4. $[Co(NH_3)_3Cl_3]$ lacks external counter-ions. Consequently, it does not dissociate into ions in solution, existing as a neutral molecule. As such, it is a non-electrolyte with minimal conductance.

The complex exhibiting minimum conductance will be the one that generates the fewest ions in solution.

Therefore, the compound with the minimum conductance is $[Co(NH_3)_3Cl_3]$.