Number of ions produced in solution by \([Co(NH_3)_6]Cl_3\), which gives 3 moles of \(AgCl\) on reacting with \(AgNO_3\), is:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → 4
In a complex, the ions inside the square bracket stay bound to the metal; only the ions outside the coordination sphere are set free in solution and can be precipitated. One mole of the compound gives 3 moles of AgCl, so all three chloride ions are outside, and the six \( \ce{NH3} \) molecules stay bound to \( \ce{Co^3+} \) as one unit:
\( \displaystyle \ce{[Co(NH3)6]Cl3 -> [Co(NH3)6]^3+ + 3Cl^-} \)
\( \displaystyle \text{Number of ions} = 1\ \text{complex cation} + 3\ \ce{Cl-} = 4 \)
So the compound is a 1:3 electrolyte and gives 4 ions. With silver nitrate:
\( \displaystyle \ce{[Co(NH3)6]Cl3 + 3AgNO3 -> [Co(NH3)6](NO3)3 + 3AgCl v} \)
NCERT (2026-27 edition):
Werner’s Theory of Coordination Compounds – “… 1 mol CoCl3.6NH3 (Yellow) gave 3 mol AgCl
1 mol CoCl3.5NH3 (Purple) gave 2 mol AgCl
1 mol CoCl3.4NH3 (Green) gave 1 mol AgCl
1 mol CoCl3.4NH3 (Violet) gave 1 mol AgCl”
Formulation of Cobalt(III) Chloride-Ammonia Complexes (row)
| Colour | Formula | Solution conductivity corresponds to |
|---|---|---|
| Yellow | [Co(NH3)6]3+3Cl– | 1:3 electrolyte |