What is the potential of a cell made up of Zn/Zn2+ and Cu/Cu2+ half-cells at 25ºC if [Zn2+] = 0.25 M and [Cu2+] = 0.15 M?

Respuesta :

Answer:

Cell potential = +1.09V

Explanation:

Given:

[Zn2+] = 0.25 M

[Cu2+]  = 0.15 M

In this electrochemical cell, Zn/Zn2+ half cell will serve as the anode and Cu/Cu2+ will act as the cathode.

The two half reactions and the reduction potentials based on the standard reduction potential chart are:

Anode (Oxidation):

[tex]Zn(s)\rightarrow Zn^{2+}(aq)+2e^{-}[/tex].......E°(anode) = -0.76 V

Cathode(Reduction):

[tex]Cu^{2+}(aq)+2e^{-}\rightarrow Cu(s)[/tex]........E°(cathode)= +0.34 V

Overall reaction:

[tex]Zn(s) + Cu^{2+}(aq)\rightarrow Cu(s) + Zn^{2+}(aq)[/tex]

[tex]E_{cell}^{0} =E_{cathode}^{0}-E_{anode}^{0}=0.34-(-0.76)=1.10V[/tex]

Based on the Nernst equation:

[tex]Ecell = E_{cell}^{0}-\frac{0.0592V}{n}log\frac{[Zn2+]}{[Cu2+]}[/tex]

[tex]Ecell = 1.10-\frac{0.0592V}{2}log\frac{[0.25]}{[0.15]}=1.09V[/tex]