Question

Selective Reduction The standard reduction potential for the half-reaction: Sn4+ + 2e - Sn2+ is +0.15 V. Consider data from the table of standard reduction potentials for common half-reactions, in your text. For a galvanic cell under standard conditions, which of the following anodic half reactions would produce, at the cathode a spontaneous reduction of Sn4+ to Sn2+ but not Sn2+ to Sn. no yes yes yes yes yes Fe — Fe2+ + 2e- Sn2+ Sn4+ + 2e- Sn Sn2+ + 2e- H2 + 2H+ + 2e- Pb + Pb2+ + 2e- H2 + 2OH - 2H20 + 2e-

Answer 1

Sn^+ + 2€ → Sn?+ E° = +0.15V Sn²+ + 2e → Sn E° =-0.141V a) To occur spontaneous reduction of Sn+ to Sn2+ but not Sn2+ to Sn, standard reduction potential of half reaction should be in between +0.15V to -0.141V. So only the following half reactions can produce above reduction at cathode 1)H, +2H+ + 2€ E' =0.00V 2)Pb → Pb2+ + 2e E° = -0.126V b) To occur spontaneous oxidation of Snto Sn2+ but not Sn2+ to Sn“, standard reduction potential of half reaction should be in between -0.141V to +0.15V. So only the following half reactions can produce above oxidation at anode 1) 2H+ + 2e →H, E =0.00V