Question:
Write the Nernst equation for the cell reaction in the Daniel cell. How will the ECell be affected when the concentration of Zn2+ ions is increased?
Solution:
Ecell = E°cell – RT[Zn2+]/ nF[Cu2+]
Galvanic cell reaction: Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s)
Anode- oxidation half-cell: Zn(s) → Zn2+ (aq)+ 2e
Cathode- reduction half-cell: Cu2+ (aq)+ 2e-→ Cu(s)
Overall reaction: Zn(s) + Cu2+ (aq) → Zn2+(aq) +Cu(s)
[Zn2+] and [Cu2+] are the concentration of the Zn2+ and Cu2+ ion in the solution.
Ecell = E°cell – 0.059/2[Zn2+]/[Cu2+]