Question

Calculate the cell potential for a given electrochemical reaction where the half-cell reactions are:* Fe3+(aq) + e- → Fe2+(aq) E° = 0.77 V* Ag+(aq) + e- → Ag(s) E° = 0.80 VAssume 1.0 M solutions and standard state conditions. Determine whether the reaction is spontaneous or non-spontaneous under standard conditions.

Answer 1

To calculate the cell potential, we first need to determine the overall balanced redox reaction. We can do this by combining the two half-cell reactions:Fe3+ aq  + e-  Fe2+ aq  E = 0.77 V  Reduction Ag+ aq  + e-  Ag s  E = 0.80 V  Reduction To combine these reactions, we need to reverse one of them so that we have one reduction and one oxidation reaction. We will reverse the Fe3+/Fe2+ reaction because it has a lower reduction potential:Fe2+ aq   Fe3+ aq  + e- E = -0.77 V  Oxidation Ag+ aq  + e-  Ag s  E = 0.80 V  Reduction Now, we can add the two half-cell reactions together to get the overall balanced redox reaction:Fe2+ aq  + Ag+ aq   Fe3+ aq  + Ag s Next, we can calculate the cell potential  Ecell  by adding the standard reduction potentials of the two half-cell reactions:Ecell = E reduction  + E oxidation Ecell = 0.80 V +  -0.77 V Ecell = 0.03 VSince the cell potential is positive  0.03 V , the reaction is spontaneous under standard conditions.