Q.14
The oxidation state of nickel atom in the coordination compound
[Ni(NH3)4Cl]Cl is:
The oxidation state of nickel in [Ni(NH₃)₄Cl]Cl is +2.
Question Breakdown
In coordination compound [Ni(NH₃)₄Cl]Cl:
- Complex ion: [Ni(NH₃)₄Cl]⁺
- Counter ion: Cl⁻ (outside coordination sphere)
Charge calculation:
- NH₃ = neutral ligand (4 × 0 = 0)
- Inside Cl = -1 charge
- Complex ion charge = +1
- Let Ni oxidation state = x
Equation: x + 0 + (-1) = +1
Solution: x = +2
Option Analysis
| Option | Why Correct/Incorrect |
|---|---|
| −1 | Impossible for transition metals in typical complexes |
| 0 | Neutral Ni would make complex [Ni(NH₃)₄Cl] neutral, but counter Cl⁻ proves +1 charge |
| +1 | Would require complex charge 0, contradicting the formula structure |
| +2 | Correct: Balances 4 neutral NH₃ + 1 Cl⁻ = +1 complex charge |
Introduction to Nickel Oxidation State [Ni(NH3)4Cl]Cl
Master nickel oxidation state [Ni(NH3)4Cl]Cl for GATE Life Sciences and CSIR NET Chemistry. This coordination compound question tests understanding of complex ion charges, ligand properties, and oxidation state calculation. Answer is +2.
Step-by-Step Oxidation State Calculation
Formula breakdown:
[Ni(NH₃)₄Cl]⁺ Cl⁻
Complex Counter
(+1) ion
Charge balance equation:
x + 4(0) + (-1) = +1
x - 1 = +1
x = +2
Key concepts:
- NH₃ = neutral ligand
- Coordination Cl⁻ = -1 (inside sphere)
- Counter Cl⁻ = outside coordination sphere
Why Other Options Are Wrong
| Choice | Error Analysis |
|---|---|
| −1 | Transition metals rarely negative |
| 0 | Ignores complex +1 charge |
| +1 | Doesn’t balance ligand charges |
| +2 | Perfect charge balance |
Exam Pattern Recognition
Common traps:
- Counting both Cl as ligands = wrong charge
- Assuming neutral complex = ignores counter ions
- Forgetting NH₃ neutrality
Pro tip: Always identify coordination sphere vs counter ions first!
Master nickel oxidation state [Ni(NH3)4Cl]Cl = +2 for competitive exam success. Practice similar complexes like [Co(NH₃)₆]Cl₃, [Pt(NH₃)₄]Cl₂.
