Chemistry Q63 – NEET-UG 2025

Home Chemistry Coordination CompoundsQuestion #361

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

Clue 1 of 3: Conductance of Complex Compounds

The electrical conductance of a solution of a complex compound is directly proportional to the number of ions produced when the complex dissociates in solution.

🥷

Ninja Strategy•Count Non-Coordinated Ions

The compound with the fewest ions outside the coordination sphere (and thus the fewest total ions upon dissociation) will exhibit the minimum electrical conductance. A neutral complex (0 external ions) will have the minimum conductance.

🧠 Full Solution Path

● Video Walkthrough

Step 1: Determine the number of ions for each complex✦ Active

The conductance of a complex in solution depends on the number of ions it produces. Ions inside the coordination sphere (within the square brackets) do not dissociate. Ions outside the coordination sphere do. We assume Cobalt is in the +3 oxidation state, which is common for these complexes, and infer external ions for neutrality where necessary:

1. $[C o (N H_{3})_{3} C l_{3}]$ : Co is +3. 3 NH $_{3}$ (neutral) and 3 Cl $^{-}$ (ligands). The complex is neutral ( $+ 3 + 0 - 3 = 0$ ). It does not dissociate into ions. Number of ions = 0.

2. $[C o (N H_{3})_{4} C l_{2}]$ : If Co is +3, the complex ion is $[C o (N H_{3})_{4} C l_{2}]^{+}$ . To be a neutral compound, it must be $[C o (N H_{3})_{4} C l_{2}] C l$ . This dissociates into 1 complex cation and 1 chloride anion. Number of ions = 2.

3. $[C o (N H_{3})_{6}] C l_{3}$ : The complex ion is $[C o (N H_{3})_{6}]^{3 +}$ (Co is +3, 6 NH $_{3}$ are neutral). It has 3 external chloride ions. This dissociates into 1 complex cation and 3 chloride anions. Number of ions = 4.

4. $[C o (N H_{3})_{5} C l] C l$ : If Co is +3, the complex ion is $[C o (N H_{3})_{5} C l]^{2 +}$ . To be a neutral compound, it must be $[C o (N H_{3})_{5} C l] C l_{2}$ . This dissociates into 1 complex cation and 2 chloride anions. Number of ions = 3.

Step 2: Compare the number of ions○ Expand

The number of ions produced by each complex is:

Option (1): 0 ions

Option (2): 2 ions

Option (3): 4 ions

Option (4): 3 ions

Step 3: Identify the complex with minimum conductance○ Expand

The complex with the minimum number of ions will exhibit the minimum conductance in solution. This corresponds to option (1), which produces 0 ions.

💡 Teacher's Secret Hint

Remember that neutral complexes do not dissociate into ions and thus have negligible conductance.

✦ STEM Console utilizes AI models to generate step-by-step explanations and math clues. AI can make mistakes.

Chemistry Question 63 – NEET-UG 2025

Clue 1 of 3: Conductance of Complex Compounds

🧠 Full Solution Path