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Chemistry · Electrochemical cells: Electrolytic and Galvanic cells, different types of electrodes, electrode potentials including standard electrode potential, half-cell and cell reactions

(acidic medium) (basic medium) (acidic medium) =0.695 \mathrm{V} \) (basic mediu

\( E_{O_{3} \mid O_{2}}^{0} \) (acidic medium) \( =2.07 \mathrm{V} \) \( E_{O_{3} \mid O_{2}}^{0} \) (basic medium) \( =1.24 \mathrm{V} \) \( E_{H_{2}}^{0} o_{2} \mid H_{2} O \) (acidic medium) \( =1.78 \mathrm{V} \) \( E_{O_{2} \mid H_{2}}^{0} O_{2}(\text { acidic medium })=0.695 \mathrm{V} \) \( E_{O_{2} \mid H_{2}}^{0},_{\Omega_{2}} \) (basic medium) \( =0.076 \mathrm{V} \) \( E_{H O_{2}^{-} \mid O H^{-}}^{0}(\text { basic medium })=0.878 \mathrm{V} \) Using the above data, find which of the following is incorrect?

  • A. Ozone is a better oxidising agent than \( H_{2} O_{2} \) in both acidic and basic medium.
  • B. \( H_{2} O_{2} \) is better oxidising agent in acidic medium than in basic medium.
  • C. \( H_{2} O_{2} \) is better reducing agent in basic medium than in acidic medium.
  • D. In basic medium \( H_{2} O_{2} \) reduces all \( O_{3} \) to \( O_{2} \) completely.

Step-by-step solution

The reduction potential of O₃/O₂ in basic medium (1.24 V) is higher than that of HO₂⁻/OH⁻ (0.878 V), making O₃ a stronger oxidant. However, for the reaction O₃ + HO₂⁻ → 2O₂ + OH⁻, the cell potential is 1.24 V - (-0.076 V) = 1.316 V, indicating spontaneity. Yet, the statement claims complete reduction, which is not guaranteed under all conditions due to competing decomposition of H₂O₂ in basic medium and potential side reactions. Additionally, the large positive potential suggests near-complete conversion, but the phrase "all" and "completely" may overstate the extent in practice. Therefore, D is incorrect.
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