Question

A student needs to determine the standard electrode potential for the following reaction: Fe3+ + e- → Fe2+ Using the standard electrode potentials of Fe3+/Fe2+ and Ag+/Ag, calculate the standard cell potential for the following reaction: 2Ag+ (aq) + Fe(s) → 2Ag(s) + Fe2+ (aq) Determine if this reaction is spontaneous or nonspontaneous under standard conditions.

Answer 1

To calculate the standard cell potential for the given reaction, we need the standard electrode potentials for both the Fe3+/Fe2+ and Ag+/Ag redox couples. The standard electrode potentials are as follows:Fe3+ + e-  Fe2+; E Fe3+/Fe2+  = +0.77 VAg+ + e-  Ag; E Ag+/Ag  = +0.80 VThe given reaction can be broken down into two half-reactions:Oxidation half-reaction  anode : Fe s   Fe2+  aq  + 2e-; E Fe2+/Fe  = - E Fe3+/Fe2+  = -0.77 VReduction half-reaction  cathode : 2Ag+  aq  + 2e-  2Ag s ; E Ag+/Ag  = +0.80 VNow, we can calculate the standard cell potential  Ecell  using the equation:Ecell = Ecathode - EanodeEcell =  +0.80 V  -  -0.77 V  = +0.80 V + 0.77 V = +1.57 VSince the standard cell potential  Ecell  is positive  +1.57 V , the reaction is spontaneous under standard conditions.