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Question #44711

Difficulty: 8/10 | 🟢 Free

The Question

An advanced electrochemical cell is designed to study the thermodynamics of 'bubble-free' water electrolysis at 298 K298\text{ K}. Two inert platinum electrodes are immersed in an aqueous buffer solution of pH=2.0pH = 2.0.

During steady-state electrolysis, the products exist entirely as dissolved gases before any bubbles can form. The local concentration of dissolved hydrogen at the cathode is maintained at 1.0×10−4 M1.0 \times 10^{-4}\text{ M}, and dissolved oxygen at the anode is 1.0×10−5 M1.0 \times 10^{-5}\text{ M}.

The Henry's Law constants for the gases in water at 298 K298\text{ K} are KH(\ceH2)=1.0×10−3 M bar−1K_H(\ce{H2}) = 1.0 \times 10^{-3}\text{ M bar}^{-1} and KH(\ceO2)=1.0×10−3 M bar−1K_H(\ce{O2}) = 1.0 \times 10^{-3}\text{ M bar}^{-1}.

Given the standard electrode potential E\ceO2(g)/H2O∘=1.23 VE^\circ_{\ce{O2(g)/H2O}} = 1.23\text{ V} and 2.303RTF=0.06 V\frac{2.303 RT}{F} = 0.06\text{ V}.

Calculate the minimum theoretical applied voltage (VminV_{min}) required to sustain this electrolysis.

Options

  • A.

    1.17 V1.17\text{ V}

  • B.

    1.035 V1.035\text{ V}

  • C.

    1.29 V1.29\text{ V}

  • D.

    1.41 V1.41\text{ V}

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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

Henry’s Law Constant (Kh) Trends|Electrolysis Product Prediction

Why This Question Is Tricky

Common Mistakes

This problem tests the intersection of Henry's Law and Electrochemistry.

Students often fall into two major traps: 1) Plugging the molar concentration of dissolved gases directly into the Nernst equation instead of converting them to equivalent partial pressures via Henry's Law (leading to Option B). 2) Incorrectly incorporating the pH of the solution into the overall cell potential for water electrolysis, failing to realize that the proton stoichiometry cancels out perfectly between the anode and cathode (leading to Options C or D).

Quick Facts About This Question

Question Information

SubjectChemistry
ChapterSolutions - Class 12
ConceptHenry’s Law Constant (Kh) Trends
Difficulty8
Cognitive Load7
Target Solve Time160 sec
AccessFree