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Question #44743

Difficulty: 8/10 | 🟢 Free

The Question

A researcher attempts to determine the limiting molar conductivity (Λm∘\Lambda_m^\circ) of the actinoid salt \ceUO2Cl\ce{UO2Cl} by preparing a 1.0×10−3 M1.0 \times 10^{-3}\text{ M} solution in a 1.0 M1.0\text{ M} \ceHClO4\ce{HClO4} buffer at 298 K298\text{ K} (to prevent hydrolysis). However, the Debye-Hückel-Onsager extrapolation fails because \ceUO2+\ce{UO2+} undergoes the following disproportionation equilibrium:

\ce2UO2+(aq)+4H+(aq)<=>U(aq)4++UO2(aq)2++2H2O(l)\ce{2UO2+_{(aq)} + 4H+_{(aq)} <=> U^{4+}_{(aq)} + UO2^{2+}_{(aq)} + 2H2O_{(l)}}

Given the standard reduction potentials E∘(\ceUO22+/\ceUO2+)=+0.162 VE^\circ(\ce{UO2^{2+}}/\ce{UO2+}) = +0.162\text{ V} and E∘(\ceUO2+/\ceU4+)=+0.280 VE^\circ(\ce{UO2+}/\ce{U^{4+}}) = +0.280\text{ V}, calculate the percentage of \ceUO2+\ce{UO2+} that has disproportionated in this buffered solution, which fundamentally alters the charge carrier composition.

(Assume ideal behavior and 2.303RTF=0.059 V\frac{2.303 RT}{F} = 0.059\text{ V})

Options

  • A.

    95.2 %

  • B.

    47.6 %

  • C.

    16.7 %

  • D.

    4.8 %

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

Kohlrausch Law Infinite Dilution|Actinoid Oxidation State Variety

Why This Question Is Tricky

Common Mistakes

This question tests the 'Chemical Exception' of dynamic disproportionation equilibria interfering with Kohlrausch's Law and Debye-Hückel-Onsager (DHO) extrapolations.

Students often assume that a dissolved salt remains as a single stable ionic species.

However, actinoids like Uranium exhibit multiple accessible oxidation states.

The trap lies in failing to account for the spontaneous disproportionation of U(V) into U(IV) and U(VI) in acidic media, which drastically alters the ionic composition and prevents the system from reaching a clean 'infinite dilution' plateau.

Distractors target common stoichiometric errors (forgetting the coefficient of 2 for UO2+, leading to 47.6%), reversing the redox potentials (16.7%), or calculating the remaining unreacted percentage (4.8%).

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterElectrochemistry - Class 12
ConceptKohlrausch Law Infinite Dilution
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree