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Question #45015

Difficulty: 8/10 | 🟢 Free

The Question

An electrochemical cell is constructed at 298 K using two Nickel half-cells. Compartment A consists of a $\ce{Ni(s)}$ electrode immersed in a solution containing $0.10\text{ M } \ce{[NiCl4]^{2-}}$ and $1.0\text{ M } \ce{Cl-}$ . Compartment B consists of a $\ce{Ni(s)}$ electrode immersed in a solution containing $0.01\text{ M } \ce{[Ni(CN)4]^{2-}}$ and $0.10\text{ M } \ce{CN-}$ . The overall formation constants are $\beta_4(\ce{[NiCl4]^{2-}}) = 10^2$ and $\beta_4(\ce{[Ni(CN)4]^{2-}}) = 10^{30}$ . Assume $\frac{2.303 RT}{F} = 0.06\text{ V}$ . Determine the spontaneous EMF of the cell, and identify the coordination geometry and hybridization of the nickel complex present in the \textbf{anodic} compartment.

Options

A.
0.75 V, Square Planar ( $dsp^2$ )
B.
0.84 V, Square Planar ( $dsp^2$ )
C.
0.75 V, Tetrahedral ( $sp^3$ )
D.
0.84 V, Tetrahedral ( $sp^3$ )

Check Your Answer

Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Exception_Exposure

Learn to identify edge cases and boundary exceptions that JEE examiners hide in math problems.

Concepts Behind This Question

Half-Reaction Media Sensitivity|Complex Ion Oxidation States|Valence Bond Theory Hybridization

Why This Question Is Tricky

Common Mistakes

This problem tests the synergy between Electrochemistry and Coordination Chemistry.

The primary trap is calculating the standard EMF ( $0.84$ V) while ignoring the Nernstian concentration shifts, which leads to incorrect option B.

Furthermore, students must correctly identify the anode by comparing the actual oxidation potentials ( $E_{ox}$ ), not just assuming Compartment A is the anode.

Finally, it tests the application of Valence Bond Theory/Crystal Field Theory: recognizing that the massive thermodynamic stability ( $\beta_4 = 10^{30}$ ) in the anodic compartment is driven by the strong field nature of $\ce{CN-}$ , which forces a transition from the typical $sp^3$ (tetrahedral) geometry of weak field $d^8$ complexes to a $dsp^2$ (square planar) geometry.

Quick Facts About This Question

Question Information

Subject	Chemistry
Chapter	Redox Reactions - Class 11 Part 2
Concept	Half-Reaction Media Sensitivity
Difficulty	8
Cognitive Load	7
Target Solve Time	160 sec
Access	Free