1. Identify the More Positive Reduction Potential:
* Look up the standard reduction potentials for copper and silver:
* Cu²⁺(aq) + 2e⁻ → Cu(s) E° = +0.34 V
* Ag⁺(aq) + e⁻ → Ag(s) E° = +0.80 V
* The higher the reduction potential, the more likely the species is to be reduced. Silver has a higher reduction potential than copper, indicating it is more easily reduced.
2. Determine the Cathode:
* The cathode is where reduction occurs (gain of electrons). Since silver has the higher reduction potential, it will be reduced at the cathode.
3. Write the Half-Reaction:
* The half-reaction at the cathode is the reduction of silver ions:
Ag⁺(aq) + e⁻ → Ag(s)
Summary:
In a galvanic cell with copper and silver electrodes, the half-reaction at the cathode is the reduction of silver ions to solid silver.
