Problem: The voltage generated by the zinc concentration cell described by. Zn(s)|Zn2+(aq,0.100 M)|| Zn2+ (aq,? M)|Zn(s) is 13.0 mV at 25  °C. Calculate the concentration of the Zn2+(aq) ion at the cathode.

FREE Expert Solution

Concentration cell → same electrodes, different concentrations

  • E°cell = 0 → same electrodes

Recall that a cell notation is written from anode (oxidation) to cathode (reduction):


lose electrons  oxidation → anode

gain electrons  reduction → cathode


Anode                              cathode

Zn(s)|Zn2+(aq,0.100 M)|| Zn2+ (aq, ? M)|Zn(s) 

  • Oxidation: Zn (s)  → Zn2+(aq)  +  2e-
  • Reduction: Zn2+(aq)  +  2eZn (s) 
    • n = 2e-


Modified Nernst Equation:


Ecell=-(0.0592 Vn)log[Zn2+]anode[Zn2+]cathode

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Problem Details

The voltage generated by the zinc concentration cell described by. 

Zn(s)|Zn2+(aq,0.100 M)|| Zn2+ (aq,? M)|Zn(s) 

is 13.0 mV at 25  °C. Calculate the concentration of the Zn2+(aq) ion at the cathode.

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