Question

For the reaction that occurs in the voltaic cell,

Fe(s)|Fe2+(aq)||Cr3+(aq), Cr2+(aq)|Pt(s)

determine E°cell.

I don't understand how the Pt(s) would be used to solve this question.

Please help!

Answer 1

Thanks for explaining what you don't understand. It makes it easier. The Pt is an inert electrode. Obviously you can't make electrodes of Cr^+3 and/or Cr^+2 (as you can with iron meta); therefore, an inert electrode is used for electrical contact. Otherwise, the Nernst equation is used to calculate Eo of the cell.