Question

A student needs to calculate the standard cell potential for the following reaction at 25°C:Zn (s) + Fe2+ (aq) → Zn2+ (aq) + Fe (s)Given:- Standard reduction potentials: Eº(Zn2+/Zn) = -0.76 V and Eº(Fe2+/Fe) = -0.44 V- Concentration of Fe2+ = 0.1 M and concentration of Zn2+ = 1.0 MWhat is the value of the standard cell potential for this reaction?

Answer 1

To calculate the standard cell potential for the given reaction, we need to first write the half-reactions for the reduction and oxidation processes:Reduction: Fe2+  aq  + 2e-  Fe  s  ; E = -0.44 VOxidation: Zn  s   Zn2+  aq  + 2e- ; E = -0.76 VNext, we need to reverse the oxidation half-reaction to make it a reduction half-reaction:Zn2+  aq  + 2e-  Zn  s  ; E = +0.76 VNow, we can add the two half-reactions to get the overall cell reaction:Fe2+  aq  + Zn  s   Zn2+  aq  + Fe  s To find the standard cell potential  E_cell , we can add the standard reduction potentials of the two half-reactions:E_cell = E_red  Fe2+/Fe  + E_red  Zn/Zn2+ E_cell =  -0.44 V  +  +0.76 V E_cell = +0.32 VSo, the standard cell potential for this reaction at 25C is +0.32 V.