A half-cell containing chlorine and chloride ions is connected to a half-cell containing nickel ions and nickel to form a voltaic cell.

Question

Determine the proper direction for each half-cell reaction to assure a spontaneous, complete cell reaction, and find the value of E°.

Answer 1

Looking up the standard reduction potentials for each half reaction, I find the following:

Cl₂ + 2e- ==> 2Cl^- Eº = 1.36 V

Ni²⁺ + 2e- ==> Ni Eº = -0.23 V

From this information, Cl₂ will be reduced (cathode) and Ni will be oxidized (anode)

The overall reaction will be:

Cl₂ + Ni ==> 2Cl^- + Ni²⁺

Eº = 1.36 + 0.23 = 1.59 V