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ChemistryNEET 2022Electrochemical cells and Nernst equation

Electrochemistry

Given below are half-cell reactions:

MnO4−+8H++5e−→Mn2++4H2O;EMn2+/MnO4−∘=−1.510 V\mathrm{MnO_4^- + 8H^+ + 5e^- \rightarrow Mn^{2+} + 4H_2O};\quad E^\circ_{\mathrm{Mn^{2+}/MnO_4^-}} = -1.510\ \mathrm{V}

12O2+2H++2e−→H2O;EO2/H2O∘=+1.223 V\tfrac12\mathrm{O_2 + 2H^+ + 2e^- \rightarrow H_2O};\quad E^\circ_{\mathrm{O_2/H_2O}} = +1.223\ \mathrm{V}

Will the permanganate ion, MnO4−\mathrm{MnO_4^-}, liberate O2\mathrm{O_2} from water in the presence of an acid?

  1. A.No, because Ecell∘=−2.733E^\circ_{cell} = -2.733 V
  2. B.Yes, because Ecell∘=+0.287E^\circ_{cell} = +0.287 V✓
  3. C.No, because Ecell∘=−0.287E^\circ_{cell} = -0.287 V
  4. D.Yes, because Ecell∘=+2.733E^\circ_{cell} = +2.733 V

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