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Question #44896

Difficulty: 8/10 | 🟢 Free

The Question

A non-aqueous electrolytic cell at 298 K298 \text{ K} contains a solution of Uranium salts where the actinoid exists as a mixture of U3+U^{3+} and U4+U^{4+} ions in a 1:11:1 molar ratio. A constant current of 19.3 A19.3 \text{ A} is passed through the cell for 5000 s5000 \text{ s} to deposit solid Uranium (\ceU(s)\ce{U_{(s)}}) at the cathode. Due to ion-pairing and solvent interactions in the non-aqueous medium, the current efficiency for the cathodic deposition is 75%75\%. Assuming both U3+U^{3+} and U4+U^{4+} are reduced to \ceU(s)\ce{U_{(s)}} simultaneously at rates proportional to their bulk mole fractions, calculate the mass of Uranium deposited. \n\n(Given: Faraday's constant F=96500 C mol−1F = 96500 \text{ C mol}^{-1}, Atomic mass of U=238 g mol−1U = 238 \text{ g mol}^{-1})

Options

  • A.

    51.0 g51.0 \text{ g}

  • B.

    68.0 g68.0 \text{ g}

  • C.

    44.6 g44.6 \text{ g}

  • D.

    59.5 g59.5 \text{ g}

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Correct Answer

Step-by-Step Solution

Explanation

How the Examiner Thinks

Numerical_Precision

Improve calculation stamina and avoid rounding errors in high-stakes competitive examinations.

Concepts Behind This Question

Actinoid Oxidation State Variety|Faraday's First and Second Laws|Standard Electrode Potential Sign Conventions

Why This Question Is Tricky

Common Mistakes

This problem tests the advanced application of Faraday's Laws in non-ideal, mixed-oxidation-state systems.

The primary 'Chemical Exception' is the non-integer nn-factor.

Students typically memorize integer nn-factors for standard reductions.

Here, the actinoid's variable oxidation states (+3+3 and +4+4) undergo simultaneous competitive reduction.

The 'Key Step' is recognizing that the effective nn-factor is a weighted average (neff=3.5n_{eff} = 3.5) based on the mole fractions of the ions.

Distractor B traps students who forget to apply the 75%75\% current efficiency.

Distractors C and D trap students who assume only one oxidation state (+4+4 or +3+3, respectively) is being reduced, ignoring the mixture dynamics.

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterD and F Block Elements - Class 12
ConceptActinoid Oxidation State Variety
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree