An electrochemical cell has the following structure - HSC - SSCE Chemistry - Question 16 - 2016 - Paper 1

To determine which electrochemical cell produces the highest cell potential, we can use the standard reduction potentials for each half-cell reaction mentioned in the options.

1. Standard Reduction Potentials: Look up the standard electrode potentials from a reliable source:

   • Mg | Mg²⁺: -2.37 V
   • Fe | Fe²⁺: -0.44 V
   • Al | Al³⁺: -1.66 V
   • Cu | Cu²⁺: +0.34 V
   • Zn | Zn²⁺: -0.76 V
   • Pb | Pb²⁺: -0.13 V
   • Ni | Ni²⁺: -0.25 V
   • Ag | Ag⁺: +0.80 V

2. Calculate Cell Potentials: The cell potential can be calculated using the formula:

   $E_{cell} = E_{cathode} - E_{anode}$

   • Option A (Mg | Mg²⁺ || Fe²⁺ | Fe):

     • Anode: Mg (-2.37 V), Cathode: Fe (-0.44 V)
     • $E_{cell} = -0.44 - (-2.37) = 1.93 ext{ V}$

   • Option B (Al | Al³⁺ || Cu²⁺ | Cu):

     • Anode: Al (-1.66 V), Cathode: Cu (+0.34 V)
     • $E_{cell} = 0.34 - (-1.66) = 2.00 ext{ V}$

   • Option C (Zn | Zn²⁺ || Pb²⁺ | Pb):

     • Anode: Zn (-0.76 V), Cathode: Pb (-0.13 V)
     • $E_{cell} = -0.13 - (-0.76) = 0.63 ext{ V}$

   • Option D (Ni | Ni²⁺ || Ag⁺ | Ag):

     • Anode: Ni (-0.25 V), Cathode: Ag (+0.80 V)
     • $E_{cell} = 0.80 - (-0.25) = 1.05 ext{ V}$

3. Comparison of Cell Potentials:

   • Option A: 1.93 V
   • Option B: 2.00 V
   • Option C: 0.63 V
   • Option D: 1.05 V

From the calculated cell potentials, it is clear that Option B (Al | Al³⁺ || Cu²⁺ | Cu) gives the highest cell potential of 2.00 V, which makes it the correct answer.